A. Duchemin - Academia.edu (original) (raw)

Papers by A. Duchemin

Research paper thumbnail of Molecular characterization of six variant Fc

Molecular Immunology, 1998

In humans\ three distinct but closely related classes of receptors that bind the Fc portion of Ig... more In humans\ three distinct but closely related classes of receptors that bind the Fc portion of IgG "FcgRI\ II\ and III# have been identi_ed[ FcgRI can bind monomeric IgG with high a.nity and has a unique third extracellular domain "EC2#[ Three very similar genes have been characterized for FcgRI "A\ B\ C#[ Although the sequences are remarkably similar\ a number of coding!region di}erences discriminate between the genes and amongst their transcripts[ Six distinct FcgRI transcripts were analysed[ Three transcripts\ one from each gene\ contain all six exons[ Only the gene A transcript appears to encode a bona _de high a.nity receptor\ a three Ig!domain membrane spanning receptor that can bind monomeric IgG[ Stop codons in the EC2 domains of the gene B and gene C isoforms would be predicted to generate secreted receptors[ Three transcripts are alternatively spliced isoforms\ one from gene A and two from gene B[ One gene B transcript encodes a two Ig!domain transmembrane receptor which has structural characteristics of a low a.nity FcgR[ Þ 0887 Elsevier Science Ltd[ All rights reserved[

Research paper thumbnail of Expression of cholecystokinin and enkephalin mRNA in discrete brain regions

Peptides, 1989

The levels of preprocholecystokinin mRNA were measured in several regions of rat brain using RNA ... more The levels of preprocholecystokinin mRNA were measured in several regions of rat brain using RNA blot analysis. In both species, high levels of expression were observed in the thalamus, amygdala, neocortical areas and hippocampus. Intermediate levels were observed in the periaqueductal grey, hypothalamus, substantia nigra, ventral tegmental area, and olfactory bulbs; little or no mRNA was detected in the caudate nucleus, nucleus accumbens, olfactory tubercle, cerebellum or a liver control. In contrast, the caudate and olfactory tubercle expressed large amounts of preproenkephalin mRNA. Other regions, such as the periaqueductal grey and olfactory bulbs, expressed both transcripts while regions like the hippocampus contained prominent amounts of preprocholecystokinin mRNA and relatively little preproenkephalin mRNA. Neuropeptides Opioid peptides Thalamus Cerebral cortex Basal ganglia mRNA Cholecystokinin Enkephalin

Research paper thumbnail of Pharmacological Characterization of 3H-LSD Binding Sites in Mouse Brain in Vivo

Abstracts, 1978

ABSTRACT In mice receiving i.v. low doses of 3H-LSD the accumulation of radioactivity in brain ap... more ABSTRACT In mice receiving i.v. low doses of 3H-LSD the accumulation of radioactivity in brain appears to reflect a selective binding to high affinity sites as indicated by the heterogenous regional distribution (paralleling that observed in in vitro binding studies) and by the saturable character of the process (ED50 around 30μg.kg−1 in cerebral cortex).The identity of the binding sites was assessed in various regions by administration of agonists or antagonists of different neurotransmitters. In cortex specific accumulation of 3H-LSD was easily prevented by administration of serotonin antagonists (cyproheptadine, methysergide, methiothepin) or by tryptamine derivatives (psilocin, psilocybin, dimethyltryptamine) and 5-hydroxytryptophan + pargyline. Among neuroleptics some prevented 3H-LSD binding (spiperone, haloperidol) whereas 1mg.kg−1 pimozide was ineffective. In addition a large variety of agents (adrenergic, cholinergic, morphine) were ineffective. These data suggest a selective binding to cortical serotonin receptors.

Research paper thumbnail of Labeling of histamine H1-receptors in the brain of the living mouse

Neuroscience Letters, 1980

Research paper thumbnail of GM1 increases the content and mRNA of NGF in the brain of aged rats

NeuroReport, 1997

AGED (20-22 months old) and young (3 months old) Sprague-Dawley rats were treated with GM1 gangli... more AGED (20-22 months old) and young (3 months old) Sprague-Dawley rats were treated with GM1 ganglioside, 30 mg/kg i.p. for 30 days, and the content of nerve growth factor (NGF) and the high-affinity tyrosine receptor kinase (Trk) examined. NGF, estimated by a two-site enzyme immunoassay, was found moderately decreased in the frontal cortex and hippocampus, but not in the striatum of aged animals compared with young animals. The NGF decrease was accompanied by a reduction of NGF mRNA, evaluated by northern blot. Trk protein, determined by western blot with a pan-Trk antibody, was not altered in any region studied in the aged brain. GM1 treatment partially restored NGF and NGF mRNA in frontal cortex and hippocampus in the aged brain, but treatment had no effect on Trk protein. GM1 did not modify any of the parameters investigated in young animals.

Research paper thumbnail of Nicotine-induced changes of brain β-endorphin

Neuropeptides, 2012

A consensus has emerged that endogenous opioid peptides and their receptors play an important rol... more A consensus has emerged that endogenous opioid peptides and their receptors play an important role in the psychoactive properties of nicotine. Although behavioral studies have shown that b-endorphin contributes to the rewarding and emotional effects of nicotine, whether the drug alters the function of brain endorphinergic neurons is not fully explored. These studies investigated the effect of acute, 1 mg/kg, sc, and chronic, daily injection of 1 mg/kg, sc, for 14 days, administration of free base nicotine on brain b-endorphin and its precursor proopiomelanocortin (POMC). Acute and chronic treatment with nicotine decreased b-endorphin content in hypothalamus, the principal site of b-endorphin producing neurons in the brain, and in the endorphinergic terminal fields in striatum and hippocampus. The acute effect of nicotine on b-endorphin was reversed by the nicotinic antagonist mecamylamine and the dopamine antagonist haloperidol, indicating pharmacological specificity and involvement of dopamine D2-like receptors. Similar observations were made in prefrontal cortex. POMC mRNA in hypothalamus and prefrontal cortex was unchanged following acute nicotine, but it decreased moderately with chronic treatment. The nicotine treatments had no effect on pituitary and plasma b-endorphin. Taken together, these results could be interpreted to indicate that nicotine alters the synthesis and release of b-endorphin in the limbic brain in vivo. Altered endorphinergic function may contribute to the behavioral effects of acute and chronic nicotine treatment and play a role in nicotine addiction.

Research paper thumbnail of Age-related changes in the expression of the glutamate transporter from rat cerebral cortical poly A(+) mRNA in Xenopus laevis oocytes

Neurochemistry International, 1991

ABSTRACT Cerebral cortical poly A(+) mRNA was prepared from rats of various age and injected into... more ABSTRACT Cerebral cortical poly A(+) mRNA was prepared from rats of various age and injected into Xenopus laevis oocytes. Glutamate transporter activity was studied in the oocytes and the results compared with glutamate uptake into synaptosomes prepared from cerebral cortex and striatum from animals of the same age. Both expressed and synaptosomal glutamate transport activity were present in brain at 1 day of age, increased with age and appeared maximum by about 30 days of age. A dissociation between expressed and synaptosomal transport activity was observed for 1 year old animals, when the expressed activity declined. In senescent rats both activities declined. These results suggest that reduced glutamate transporter activity in senescent brain is not limited to protein synthesis, but may involve the genetic mechanisms controlling transporter expression.

Research paper thumbnail of Expression of cloned aromatic l-amino acid decarboxylase in Xenopus laevis oocytes

Neurochemistry International, 1992

Sense mRNA coding for bovine adrenal medulla aromatic L-amino acid decarboxylase (AADC) was expre... more Sense mRNA coding for bovine adrenal medulla aromatic L-amino acid decarboxylase (AADC) was expressed following microinjection into Xenopus laevis oocytes. The expressed enzyme activity was stereoselective for L-5-hydroxytryptophan and L-DOPA and blocked by NSD-1015 an inhibitor of AADC. Heating the expressed enzyme at 55 degrees C resulted in a parallel loss of activity towards both substrates. Our findings are consistent with the prevailing notion that a single enzyme is able to decarboxylate both substrates in vivo.

Research paper thumbnail of Onco-neural antibodies and tumour type determine survival and neurological symptoms in paraneoplastic neurological syndromes with Hu or CV2/CRMP5 antibodies

Journal of Neurology, Neurosurgery & Psychiatry, 2008

Objective Anti-Hu antibodies (Hu-Ab) and anti-CV2/CRMP5 antibodies (CV2/CRMP5-Ab) have been ident... more Objective Anti-Hu antibodies (Hu-Ab) and anti-CV2/CRMP5 antibodies (CV2/CRMP5-Ab) have been identified in association with paraneoplastic neurological disorders. However, it is not clear whether these antibodies are associated with specific neurological symptoms or are only markers of anti-cancer immune reaction. Methods To address this question, we compared 37 patients with CV2/CRMP5-Ab and 324 patients with Hu-Ab. Results Whereas the age and sex ratio were the same between the two groups, the distribution of neurological symptoms was not. Patients with CV2/CRMP5-Ab presented more frequently cerebellar ataxia, chorea, uveo/retinal symptoms and myasthenic syndrome (Lambert-Eaton myasthenic syndrome LEMS or myasthenia gravis). They also had better Rankin score. On the opposite, dysautonomia, brainstem encephalitis and peripheral neuropathy were more frequent in patients with Hu-Ab. Limbic encephalitis occurred similarly in both groups. Small cell lung cancer (SCLC) was the most frequently associated tumor in both groups of patients while malignant thymoma was observed only in patients with CV2/CRMP5-Ab. In particular, patients with CV2/CRMP5-Ab and thymoma developed more frequently myasthenic syndrome while patients with SCLC developed more frequently neuropathies. Chorea and myasthenic syndrome were only seen in patients with CV2/CRMP5-Ab. The median survival time was significantly longer in patients with CV2/CRMP5-Ab and this effect was not dependent on the type of tumor. Interpretation Our data demonstrate that in patients with paraneoplastic neurological syndromes, the neurological symptoms and survival vary with both the type of associated onco-neural antibody and the type of tumor.

Research paper thumbnail of Changes in plasma nerve growth factor levels in older adults associated with chronic stress

Journal of Neuroimmunology, 2001

Evidence indicates that the actions of nerve growth factor NGF reach beyond the nervous system an... more Evidence indicates that the actions of nerve growth factor NGF reach beyond the nervous system and might modulate immune function. Based on reports that blood NGF rises following the acute stress of parachute jumping, we investigated whether exposure to a chronic stressor, caregiving for a cognitively impaired spouse, could alter the levels of blood NGF. High perceived stress and depression Ž. in caregivers vs. well-matched controls were associated with elevated blood NGF. These data suggest that exposure to this chronic stressor can alter the concentrations of circulating NGF, and that psychological stress can induce changes in NGF concentrations in older adults.

Research paper thumbnail of Activation of aromatic l‐amino acid decarboxylase by calcium/calmodulin kinase II

Journal of Neurochemistry, 2008

Calcium/calmodulin‐dependent protein kinase II (CAMKII) is widely distributed in the brain, and i... more Calcium/calmodulin‐dependent protein kinase II (CAMKII) is widely distributed in the brain, and is involved in the regulation of neurotransmitter synthesis. Tyrosine hydroxylase and tryptophan hydroxylase, the two enzymes involved in the first step in the synthesis of catecholamines and indolamines, respectively, are phosphorylated by CAMKII. We now found that aromatic l‐amino acid decarboxylase (AAAD), the common second enzyme of both synthetic pathways, is activated by CAMKII. AAAD activity was assayed in mouse striatum homogenates with L‐DOPA as a substrate. The activation of AAAD by CAMKII in vitro is time and concentration‐dependent with maximal activity observed with 1.5 μg/mL of purified brain CAMKII and a 20‐min incubation. CAMKII induces a 30% increase of the apparent Vmax of the enzyme without changing its affinity for L‐DOPA and the cofactor pyridoxal‐5′‐phosphate. We have previously shown that AAAD can be phosphorylated by cyclic AMP‐and cyclic GMP‐dependent protein kina...

Research paper thumbnail of Phosphorylation and Activation of Brain Aromatic l‐Amino Acid Decarboxylase by Cyclic AMP‐Dependent Protein Kinase

Journal of Neurochemistry, 2002

Aromatic l‐amino acid decarboxylase (AAAD), an enzyme required for the synthesis of catecholamine... more Aromatic l‐amino acid decarboxylase (AAAD), an enzyme required for the synthesis of catecholamines, indoleamines, and trace amines, is rapidly activated by cyclic AMP‐dependent pathways in striatum and midbrain in vivo, suggesting enzyme phosphorylation. We now report that the catalytic subunit of cyclic AMP‐dependent protein kinase (PKA) directly phosphorylated AAAD immunoprecipitated from homogenates prepared from the mouse striatum and midbrain in vitro. Under the same phosphorylation conditions, the catalytic subunit of PKA also phosphorylated a recombinant AAAD protein expressed in Escherichia coli transfected with an AAAD cDNA isolated from the bovine adrenal gland. The PKA‐induced AAAD phosphorylation of immunoprecipitates from striatum and midbrain was time and concentration dependent and blocked by a specific PKA peptide inhibitor. Incubation of the catalytic subunit of PKA with striatal homogenates increased enzyme activity by ~20% in a time‐ and concentration‐dependent ma...

Research paper thumbnail of Preproenkephalin mRNA and Methionine‐Enkephalin Content Are Increased in Mouse Striatum After Treatment with Nicotine

Journal of Neurochemistry, 2002

: A single dose of nicotine increased methionine‐enkephalin (Met‐Enk) immunoreactivity in the str... more : A single dose of nicotine increased methionine‐enkephalin (Met‐Enk) immunoreactivity in the striatum of mice in a time‐dependent manner. Met‐Enk content reached a maximum by ∼1 h after nicotine and returned to control values by 6 h. The response to nicotine was blocked by pretreating animals with the nicotinic receptor antagonist mecamylamine. In contrast, pretreating mice with the muscarinic receptor antagonist atropine or the dopamine receptor antagonist haloperidol did not block the response. A single dose of nicotine also increased mRNA for the precursor peptide preproenkephalin (PPE). The increase of PPE mRNA preceded that of Met‐Enk and reached a maximum by ∼30 min after nicotine. PPE mRNA levels returned to near normal by ∼3 h and increased again by 6 h after nicotine. Daily administration of nicotine for 14 days increased Met‐Enk content and PPE mRNA in the striatum of mice as well. Taken together, our results suggest that nicotinic receptors modulate Met‐Enk content and PPE mRNA in the mouse striatum.

Research paper thumbnail of Functional Separation of Pseudopod Extension and Particle Internalization during Fcγ Receptor–mediated Phagocytosis

The Journal of Experimental Medicine, 1998

Receptors for the Fc portion of immunoglobulin (Ig)G (FcγR) mediate phagocytosis of IgG-opsonized... more Receptors for the Fc portion of immunoglobulin (Ig)G (FcγR) mediate phagocytosis of IgG-opsonized particles by a process that can be divided into four major steps: receptor–ligand binding, pseudopod extension, internalization, and lysosomal fusion. We have expressed single classes of FcγR in COS fibroblasts to examine the structural determinants necessary to complete the four steps of phagocytosis. Using phase contrast, fluorescence, confocal, and electron microscopy we have demonstrated that FcγR-expressing COS cells can phagocytose in a manner similar to that of professional phagocytes. We have further analyzed the capacity of the three classes of FcγR to phagocytose, placing special emphasis on the FcγRIA–γ chain complex, which allowed us to examine independently the roles of the ligand-binding unit (FcγRIA) and the signaling unit (γ chain). We found that receptor complexes containing a conserved tyrosine activation motif (ITAM), as found in the cytoplasmic domain of FcγRIIA and ...

Research paper thumbnail of Modulation of tyrosine hydroxylase and aromatic l-amino acid decarboxylase after inhibiting monoamine oxidase-A

European Journal of Pharmacology, 1996

After acute administration of the monoamine oxidase inhibitor clorgyline there is a reduction of ... more After acute administration of the monoamine oxidase inhibitor clorgyline there is a reduction of aromatic L-amino acid decarboxylase and tyrosine hydroxylase activity in the mouse striatum. Similar responses were seen after administering the non-selective monoamine oxidase inhibitor pargyline and high, but not low, doses of the selective monoamine oxidase-B inhibitor deprenyl. Changes of tyrosine hydroxylase activity were observed only when subsaturated concentrations of the pteridine cofactor were used for the assay. The monoamine oxidase inhibitors altered the abundance of aromatic L-amino acid decarboxylase and tyrosine hydroxylase mRNA in the midbrain. Pargyline and high doses of deprenyl increased aromatic L-amino acid decarboxylase mRNA, while clorgyline initially decreased and then increased it. All three compounds caused an early decrease of tyrosine hydroxylase mRNA. The acidic metabolites of dopamine appeared most affected by pargyline and clorgyline, supporting the notion that deamination of striatal dopamine in rodents is primarily by monoamine oxidase-A. Our results suggest that striatal tyrosine hydroxylase and aromatic L-amino acid decarboxylase are apparently modulated via different mechanisms in response to perturbation of dopamine metabolism.

Research paper thumbnail of Parallel modulation of striatal dopamine synthetic enzymes by second messenger pathways

European Journal of Pharmacology, 1998

The activity of tyrosine hydroxylase and aromatic L-amino acid decarboxylase in the striatum and ... more The activity of tyrosine hydroxylase and aromatic L-amino acid decarboxylase in the striatum and their mRNA content in the midbrain were assayed in mice following the intracerebroventricular injection of forskolin or phorbol-12,13-myristic acid (PMA). Control and 1-methyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned animals were studied. Both forskolin and PMA induced a rapid and transient increase of tyrosine hydroxylase and aromatic L-amino acid decarboxylase activity in the striatum that lasted less than 45 and 60 min, respectively. A second belated increase of striatal tyrosine hydroxylase and aromatic L-amino acid decarboxylase activities was seen only after forskolin, and it was accompanied by a rise of tyrosine hydroxylase and aromatic L-amino acid decarboxylase mRNA in the midbrain. In the MPTP-lesioned mouse, the rise of tyrosine hydroxylase and aromatic L-amino acid decarboxylase following forskolin appeared exaggerated, while the response to PMA was not. These studies suggest that tyrosine hydroxylase and aromatic L-amino acid decarboxylase of striatum can be modulated in parallel by protein kinase A and protein kinase C, and that exaggerated responsiveness to protein kinase A is observed in the partially denervated striatum.

Research paper thumbnail of 1,1,3 Tricyano-2-amino-1-propene (Triap): a small molecule which mimics or potentiates nerve growth factor

Developmental Brain Research, 1990

1,1,3 Tricyano-2-amino-l-propene (Trlap) is a small molecular weight compound which increases the... more 1,1,3 Tricyano-2-amino-l-propene (Trlap) is a small molecular weight compound which increases the rate of nerve and tissue regeneration m several experimental systems Early experiments with this compound showed that, like nerve growth factor (NGF), Trlap induced neurite formation in chick spinal ganglia To assess the similarity between NGF and Triap, we compared the effects of Triap and NGF on a rat pheochromocytoma cell line (PC12) and on cell survival in a primary chick neuronal culture In the latter, Triap at ~<0 01 nM preserved neurons and caused them to extend neurites as did 1 nM NGF Triap induced neurlte outgrowth in the PC12 cell hne giving a maximal response (40-50% of the maximal response of NGF) at a concentration of 20/~g/ml (151/~M) Triap's morphological effects were not inhibited by antibodies directed against NGF or the NGF receptor Low concentrations of Triap also potentiated the morphological effects of NGF Triap induced an increase in cell-substratum adhesion and cellular hypertrophy in PC12 cells and also potentiated the adhesive actions of NGF Tnap had no effect on ornithine decarboxylase activity even though it potentiated NGF's effects on this enzyme These data indicate that Trlap reduces neurotrophlc effects and does not seem to act through the same mechanisms as NGF but can potentiate many of NGF's morphological and biochemical actions

Research paper thumbnail of Hydra head activator peptide has trophic activity for eukaryotic neurons

Developmental Brain Research, 1992

The synthetic undecameric peptide, pGlu-Pro-Pro-Gly-Gly-Ser-Lys-Val-Ile-Leu-Phe, known as the hyd... more The synthetic undecameric peptide, pGlu-Pro-Pro-Gly-Gly-Ser-Lys-Val-Ile-Leu-Phe, known as the hydra head activator peptide, present in high concentrations in mammalian hypothalamus and intestine, was tested for neurotrophic activity in a survival assay using cultured chick embryonic sympathetic and dorsal root ganglion cells, and for morphological differentiation activity on neuroblastoma cells. Hydra head activator peptide supported neuron survival. The optimal active concentration, 1 pM, was very similar to the concentration that causes bud and head formation in hydra. Maximal neuron survival obtained with hydra head activator peptide was close to that obtained with nerve growth factor: both substances enhanced survival up to 3 times that of control cultures. Bradykinin, which has some amino acid sequence homology with hydra head activator, was inactive as a neurotrophic factor. Hydra head activator induced rapid morphological differentiation of the mouse neuroblastoma cell line Neuro-2A. Neuro-2A responded to the peptide by process extension, 4 h after its addition to the culture medium. Neurotrophic factors isolated to date have been characterized by their ability to maintain cell viability and enhance neurite outgrowth. Hydra head activator peptide met these two criteria when tested in 3 different neuron culture systems. Our results suggest that the head activator peptide may act as a neurotrophic factor for neurons in other species, including mammals.

Research paper thumbnail of Expression of neurotrophic activity in Xenopus oocytes injected with mRNA from wounded rat cerebral cortex

Molecular Brain Research, 1990

Injury to the cerebral cortex of the rat brain has been shown to induce the expression of neurotr... more Injury to the cerebral cortex of the rat brain has been shown to induce the expression of neurotrophic factors for dissociated peripheral and central neurons in culture. We confirm this phenomenon and report that Xenopus laevis oocytes injected with mRNA extracted from wounded rat cortex expressed similar neurotrophic activity. To detect the low amounts of neurotrophic factors that could be expected from the oocyte translation system, a miniaturization of the assay for neurotrophic and cell-surviving activity was developed using Terasaki microtiter plates for culture of chicken embryo sympathetic ganglion cells. Messenger RNA (mRNA) was size-fractionated on a sucrose gradient and RNAs from each fraction were injected into oocytes. Neurotrophic activity was recovered from the homogenates and from the incubation media of oocytes injected with mRNA from 7 day post-lesion cortex. Messenger RNAs in the active fractions ranged in size from 0.8 to 1.8 kb. As much as 20% of the activity was secreted by the oocytes. No significant neurotrophic activity was detected from oocytes injected with mRNA fractions extracted from the cortex of control rats or from other gradient fractions from post-lesion cortex.

Research paper thumbnail of Tyrosine hydroxylase, aromatic l-amino acid decarboxylase and dopamine metabolism after chronic treatment with dopaminergic drugs

Brain Research, 1999

1H-3-benzazepine-7,8-diol DA D-like ; bromocriptine, DA D selective ; quinpirole, DA D rD preferr... more 1H-3-benzazepine-7,8-diol DA D-like ; bromocriptine, DA D selective ; quinpirole, DA D rD preferring ; "-7-2 1 patterns of change did not follow those for TH or AAAD. When studied 48 h after the last dose of the chronic haloperidol schedule TH displayed tolerance to acute drug challenge. At the same time interval, there was tolerance to the enhancing effects of haloperidol and SCH 23390 on DA metabolism. The induction of AAAD by haloperidol or SCH 23990 did not appear to develop tolerance after chronic administration. These observations complement existing knowledge, and provide novel information about AAAD that may have practical importance for Parkinson's patients on L-DOPA therapy.

Research paper thumbnail of Molecular characterization of six variant Fc

Molecular Immunology, 1998

In humans\ three distinct but closely related classes of receptors that bind the Fc portion of Ig... more In humans\ three distinct but closely related classes of receptors that bind the Fc portion of IgG "FcgRI\ II\ and III# have been identi_ed[ FcgRI can bind monomeric IgG with high a.nity and has a unique third extracellular domain "EC2#[ Three very similar genes have been characterized for FcgRI "A\ B\ C#[ Although the sequences are remarkably similar\ a number of coding!region di}erences discriminate between the genes and amongst their transcripts[ Six distinct FcgRI transcripts were analysed[ Three transcripts\ one from each gene\ contain all six exons[ Only the gene A transcript appears to encode a bona _de high a.nity receptor\ a three Ig!domain membrane spanning receptor that can bind monomeric IgG[ Stop codons in the EC2 domains of the gene B and gene C isoforms would be predicted to generate secreted receptors[ Three transcripts are alternatively spliced isoforms\ one from gene A and two from gene B[ One gene B transcript encodes a two Ig!domain transmembrane receptor which has structural characteristics of a low a.nity FcgR[ Þ 0887 Elsevier Science Ltd[ All rights reserved[

Research paper thumbnail of Expression of cholecystokinin and enkephalin mRNA in discrete brain regions

Peptides, 1989

The levels of preprocholecystokinin mRNA were measured in several regions of rat brain using RNA ... more The levels of preprocholecystokinin mRNA were measured in several regions of rat brain using RNA blot analysis. In both species, high levels of expression were observed in the thalamus, amygdala, neocortical areas and hippocampus. Intermediate levels were observed in the periaqueductal grey, hypothalamus, substantia nigra, ventral tegmental area, and olfactory bulbs; little or no mRNA was detected in the caudate nucleus, nucleus accumbens, olfactory tubercle, cerebellum or a liver control. In contrast, the caudate and olfactory tubercle expressed large amounts of preproenkephalin mRNA. Other regions, such as the periaqueductal grey and olfactory bulbs, expressed both transcripts while regions like the hippocampus contained prominent amounts of preprocholecystokinin mRNA and relatively little preproenkephalin mRNA. Neuropeptides Opioid peptides Thalamus Cerebral cortex Basal ganglia mRNA Cholecystokinin Enkephalin

Research paper thumbnail of Pharmacological Characterization of 3H-LSD Binding Sites in Mouse Brain in Vivo

Abstracts, 1978

ABSTRACT In mice receiving i.v. low doses of 3H-LSD the accumulation of radioactivity in brain ap... more ABSTRACT In mice receiving i.v. low doses of 3H-LSD the accumulation of radioactivity in brain appears to reflect a selective binding to high affinity sites as indicated by the heterogenous regional distribution (paralleling that observed in in vitro binding studies) and by the saturable character of the process (ED50 around 30μg.kg−1 in cerebral cortex).The identity of the binding sites was assessed in various regions by administration of agonists or antagonists of different neurotransmitters. In cortex specific accumulation of 3H-LSD was easily prevented by administration of serotonin antagonists (cyproheptadine, methysergide, methiothepin) or by tryptamine derivatives (psilocin, psilocybin, dimethyltryptamine) and 5-hydroxytryptophan + pargyline. Among neuroleptics some prevented 3H-LSD binding (spiperone, haloperidol) whereas 1mg.kg−1 pimozide was ineffective. In addition a large variety of agents (adrenergic, cholinergic, morphine) were ineffective. These data suggest a selective binding to cortical serotonin receptors.

Research paper thumbnail of Labeling of histamine H1-receptors in the brain of the living mouse

Neuroscience Letters, 1980

Research paper thumbnail of GM1 increases the content and mRNA of NGF in the brain of aged rats

NeuroReport, 1997

AGED (20-22 months old) and young (3 months old) Sprague-Dawley rats were treated with GM1 gangli... more AGED (20-22 months old) and young (3 months old) Sprague-Dawley rats were treated with GM1 ganglioside, 30 mg/kg i.p. for 30 days, and the content of nerve growth factor (NGF) and the high-affinity tyrosine receptor kinase (Trk) examined. NGF, estimated by a two-site enzyme immunoassay, was found moderately decreased in the frontal cortex and hippocampus, but not in the striatum of aged animals compared with young animals. The NGF decrease was accompanied by a reduction of NGF mRNA, evaluated by northern blot. Trk protein, determined by western blot with a pan-Trk antibody, was not altered in any region studied in the aged brain. GM1 treatment partially restored NGF and NGF mRNA in frontal cortex and hippocampus in the aged brain, but treatment had no effect on Trk protein. GM1 did not modify any of the parameters investigated in young animals.

Research paper thumbnail of Nicotine-induced changes of brain β-endorphin

Neuropeptides, 2012

A consensus has emerged that endogenous opioid peptides and their receptors play an important rol... more A consensus has emerged that endogenous opioid peptides and their receptors play an important role in the psychoactive properties of nicotine. Although behavioral studies have shown that b-endorphin contributes to the rewarding and emotional effects of nicotine, whether the drug alters the function of brain endorphinergic neurons is not fully explored. These studies investigated the effect of acute, 1 mg/kg, sc, and chronic, daily injection of 1 mg/kg, sc, for 14 days, administration of free base nicotine on brain b-endorphin and its precursor proopiomelanocortin (POMC). Acute and chronic treatment with nicotine decreased b-endorphin content in hypothalamus, the principal site of b-endorphin producing neurons in the brain, and in the endorphinergic terminal fields in striatum and hippocampus. The acute effect of nicotine on b-endorphin was reversed by the nicotinic antagonist mecamylamine and the dopamine antagonist haloperidol, indicating pharmacological specificity and involvement of dopamine D2-like receptors. Similar observations were made in prefrontal cortex. POMC mRNA in hypothalamus and prefrontal cortex was unchanged following acute nicotine, but it decreased moderately with chronic treatment. The nicotine treatments had no effect on pituitary and plasma b-endorphin. Taken together, these results could be interpreted to indicate that nicotine alters the synthesis and release of b-endorphin in the limbic brain in vivo. Altered endorphinergic function may contribute to the behavioral effects of acute and chronic nicotine treatment and play a role in nicotine addiction.

Research paper thumbnail of Age-related changes in the expression of the glutamate transporter from rat cerebral cortical poly A(+) mRNA in Xenopus laevis oocytes

Neurochemistry International, 1991

ABSTRACT Cerebral cortical poly A(+) mRNA was prepared from rats of various age and injected into... more ABSTRACT Cerebral cortical poly A(+) mRNA was prepared from rats of various age and injected into Xenopus laevis oocytes. Glutamate transporter activity was studied in the oocytes and the results compared with glutamate uptake into synaptosomes prepared from cerebral cortex and striatum from animals of the same age. Both expressed and synaptosomal glutamate transport activity were present in brain at 1 day of age, increased with age and appeared maximum by about 30 days of age. A dissociation between expressed and synaptosomal transport activity was observed for 1 year old animals, when the expressed activity declined. In senescent rats both activities declined. These results suggest that reduced glutamate transporter activity in senescent brain is not limited to protein synthesis, but may involve the genetic mechanisms controlling transporter expression.

Research paper thumbnail of Expression of cloned aromatic l-amino acid decarboxylase in Xenopus laevis oocytes

Neurochemistry International, 1992

Sense mRNA coding for bovine adrenal medulla aromatic L-amino acid decarboxylase (AADC) was expre... more Sense mRNA coding for bovine adrenal medulla aromatic L-amino acid decarboxylase (AADC) was expressed following microinjection into Xenopus laevis oocytes. The expressed enzyme activity was stereoselective for L-5-hydroxytryptophan and L-DOPA and blocked by NSD-1015 an inhibitor of AADC. Heating the expressed enzyme at 55 degrees C resulted in a parallel loss of activity towards both substrates. Our findings are consistent with the prevailing notion that a single enzyme is able to decarboxylate both substrates in vivo.

Research paper thumbnail of Onco-neural antibodies and tumour type determine survival and neurological symptoms in paraneoplastic neurological syndromes with Hu or CV2/CRMP5 antibodies

Journal of Neurology, Neurosurgery & Psychiatry, 2008

Objective Anti-Hu antibodies (Hu-Ab) and anti-CV2/CRMP5 antibodies (CV2/CRMP5-Ab) have been ident... more Objective Anti-Hu antibodies (Hu-Ab) and anti-CV2/CRMP5 antibodies (CV2/CRMP5-Ab) have been identified in association with paraneoplastic neurological disorders. However, it is not clear whether these antibodies are associated with specific neurological symptoms or are only markers of anti-cancer immune reaction. Methods To address this question, we compared 37 patients with CV2/CRMP5-Ab and 324 patients with Hu-Ab. Results Whereas the age and sex ratio were the same between the two groups, the distribution of neurological symptoms was not. Patients with CV2/CRMP5-Ab presented more frequently cerebellar ataxia, chorea, uveo/retinal symptoms and myasthenic syndrome (Lambert-Eaton myasthenic syndrome LEMS or myasthenia gravis). They also had better Rankin score. On the opposite, dysautonomia, brainstem encephalitis and peripheral neuropathy were more frequent in patients with Hu-Ab. Limbic encephalitis occurred similarly in both groups. Small cell lung cancer (SCLC) was the most frequently associated tumor in both groups of patients while malignant thymoma was observed only in patients with CV2/CRMP5-Ab. In particular, patients with CV2/CRMP5-Ab and thymoma developed more frequently myasthenic syndrome while patients with SCLC developed more frequently neuropathies. Chorea and myasthenic syndrome were only seen in patients with CV2/CRMP5-Ab. The median survival time was significantly longer in patients with CV2/CRMP5-Ab and this effect was not dependent on the type of tumor. Interpretation Our data demonstrate that in patients with paraneoplastic neurological syndromes, the neurological symptoms and survival vary with both the type of associated onco-neural antibody and the type of tumor.

Research paper thumbnail of Changes in plasma nerve growth factor levels in older adults associated with chronic stress

Journal of Neuroimmunology, 2001

Evidence indicates that the actions of nerve growth factor NGF reach beyond the nervous system an... more Evidence indicates that the actions of nerve growth factor NGF reach beyond the nervous system and might modulate immune function. Based on reports that blood NGF rises following the acute stress of parachute jumping, we investigated whether exposure to a chronic stressor, caregiving for a cognitively impaired spouse, could alter the levels of blood NGF. High perceived stress and depression Ž. in caregivers vs. well-matched controls were associated with elevated blood NGF. These data suggest that exposure to this chronic stressor can alter the concentrations of circulating NGF, and that psychological stress can induce changes in NGF concentrations in older adults.

Research paper thumbnail of Activation of aromatic l‐amino acid decarboxylase by calcium/calmodulin kinase II

Journal of Neurochemistry, 2008

Calcium/calmodulin‐dependent protein kinase II (CAMKII) is widely distributed in the brain, and i... more Calcium/calmodulin‐dependent protein kinase II (CAMKII) is widely distributed in the brain, and is involved in the regulation of neurotransmitter synthesis. Tyrosine hydroxylase and tryptophan hydroxylase, the two enzymes involved in the first step in the synthesis of catecholamines and indolamines, respectively, are phosphorylated by CAMKII. We now found that aromatic l‐amino acid decarboxylase (AAAD), the common second enzyme of both synthetic pathways, is activated by CAMKII. AAAD activity was assayed in mouse striatum homogenates with L‐DOPA as a substrate. The activation of AAAD by CAMKII in vitro is time and concentration‐dependent with maximal activity observed with 1.5 μg/mL of purified brain CAMKII and a 20‐min incubation. CAMKII induces a 30% increase of the apparent Vmax of the enzyme without changing its affinity for L‐DOPA and the cofactor pyridoxal‐5′‐phosphate. We have previously shown that AAAD can be phosphorylated by cyclic AMP‐and cyclic GMP‐dependent protein kina...

Research paper thumbnail of Phosphorylation and Activation of Brain Aromatic l‐Amino Acid Decarboxylase by Cyclic AMP‐Dependent Protein Kinase

Journal of Neurochemistry, 2002

Aromatic l‐amino acid decarboxylase (AAAD), an enzyme required for the synthesis of catecholamine... more Aromatic l‐amino acid decarboxylase (AAAD), an enzyme required for the synthesis of catecholamines, indoleamines, and trace amines, is rapidly activated by cyclic AMP‐dependent pathways in striatum and midbrain in vivo, suggesting enzyme phosphorylation. We now report that the catalytic subunit of cyclic AMP‐dependent protein kinase (PKA) directly phosphorylated AAAD immunoprecipitated from homogenates prepared from the mouse striatum and midbrain in vitro. Under the same phosphorylation conditions, the catalytic subunit of PKA also phosphorylated a recombinant AAAD protein expressed in Escherichia coli transfected with an AAAD cDNA isolated from the bovine adrenal gland. The PKA‐induced AAAD phosphorylation of immunoprecipitates from striatum and midbrain was time and concentration dependent and blocked by a specific PKA peptide inhibitor. Incubation of the catalytic subunit of PKA with striatal homogenates increased enzyme activity by ~20% in a time‐ and concentration‐dependent ma...

Research paper thumbnail of Preproenkephalin mRNA and Methionine‐Enkephalin Content Are Increased in Mouse Striatum After Treatment with Nicotine

Journal of Neurochemistry, 2002

: A single dose of nicotine increased methionine‐enkephalin (Met‐Enk) immunoreactivity in the str... more : A single dose of nicotine increased methionine‐enkephalin (Met‐Enk) immunoreactivity in the striatum of mice in a time‐dependent manner. Met‐Enk content reached a maximum by ∼1 h after nicotine and returned to control values by 6 h. The response to nicotine was blocked by pretreating animals with the nicotinic receptor antagonist mecamylamine. In contrast, pretreating mice with the muscarinic receptor antagonist atropine or the dopamine receptor antagonist haloperidol did not block the response. A single dose of nicotine also increased mRNA for the precursor peptide preproenkephalin (PPE). The increase of PPE mRNA preceded that of Met‐Enk and reached a maximum by ∼30 min after nicotine. PPE mRNA levels returned to near normal by ∼3 h and increased again by 6 h after nicotine. Daily administration of nicotine for 14 days increased Met‐Enk content and PPE mRNA in the striatum of mice as well. Taken together, our results suggest that nicotinic receptors modulate Met‐Enk content and PPE mRNA in the mouse striatum.

Research paper thumbnail of Functional Separation of Pseudopod Extension and Particle Internalization during Fcγ Receptor–mediated Phagocytosis

The Journal of Experimental Medicine, 1998

Receptors for the Fc portion of immunoglobulin (Ig)G (FcγR) mediate phagocytosis of IgG-opsonized... more Receptors for the Fc portion of immunoglobulin (Ig)G (FcγR) mediate phagocytosis of IgG-opsonized particles by a process that can be divided into four major steps: receptor–ligand binding, pseudopod extension, internalization, and lysosomal fusion. We have expressed single classes of FcγR in COS fibroblasts to examine the structural determinants necessary to complete the four steps of phagocytosis. Using phase contrast, fluorescence, confocal, and electron microscopy we have demonstrated that FcγR-expressing COS cells can phagocytose in a manner similar to that of professional phagocytes. We have further analyzed the capacity of the three classes of FcγR to phagocytose, placing special emphasis on the FcγRIA–γ chain complex, which allowed us to examine independently the roles of the ligand-binding unit (FcγRIA) and the signaling unit (γ chain). We found that receptor complexes containing a conserved tyrosine activation motif (ITAM), as found in the cytoplasmic domain of FcγRIIA and ...

Research paper thumbnail of Modulation of tyrosine hydroxylase and aromatic l-amino acid decarboxylase after inhibiting monoamine oxidase-A

European Journal of Pharmacology, 1996

After acute administration of the monoamine oxidase inhibitor clorgyline there is a reduction of ... more After acute administration of the monoamine oxidase inhibitor clorgyline there is a reduction of aromatic L-amino acid decarboxylase and tyrosine hydroxylase activity in the mouse striatum. Similar responses were seen after administering the non-selective monoamine oxidase inhibitor pargyline and high, but not low, doses of the selective monoamine oxidase-B inhibitor deprenyl. Changes of tyrosine hydroxylase activity were observed only when subsaturated concentrations of the pteridine cofactor were used for the assay. The monoamine oxidase inhibitors altered the abundance of aromatic L-amino acid decarboxylase and tyrosine hydroxylase mRNA in the midbrain. Pargyline and high doses of deprenyl increased aromatic L-amino acid decarboxylase mRNA, while clorgyline initially decreased and then increased it. All three compounds caused an early decrease of tyrosine hydroxylase mRNA. The acidic metabolites of dopamine appeared most affected by pargyline and clorgyline, supporting the notion that deamination of striatal dopamine in rodents is primarily by monoamine oxidase-A. Our results suggest that striatal tyrosine hydroxylase and aromatic L-amino acid decarboxylase are apparently modulated via different mechanisms in response to perturbation of dopamine metabolism.

Research paper thumbnail of Parallel modulation of striatal dopamine synthetic enzymes by second messenger pathways

European Journal of Pharmacology, 1998

The activity of tyrosine hydroxylase and aromatic L-amino acid decarboxylase in the striatum and ... more The activity of tyrosine hydroxylase and aromatic L-amino acid decarboxylase in the striatum and their mRNA content in the midbrain were assayed in mice following the intracerebroventricular injection of forskolin or phorbol-12,13-myristic acid (PMA). Control and 1-methyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned animals were studied. Both forskolin and PMA induced a rapid and transient increase of tyrosine hydroxylase and aromatic L-amino acid decarboxylase activity in the striatum that lasted less than 45 and 60 min, respectively. A second belated increase of striatal tyrosine hydroxylase and aromatic L-amino acid decarboxylase activities was seen only after forskolin, and it was accompanied by a rise of tyrosine hydroxylase and aromatic L-amino acid decarboxylase mRNA in the midbrain. In the MPTP-lesioned mouse, the rise of tyrosine hydroxylase and aromatic L-amino acid decarboxylase following forskolin appeared exaggerated, while the response to PMA was not. These studies suggest that tyrosine hydroxylase and aromatic L-amino acid decarboxylase of striatum can be modulated in parallel by protein kinase A and protein kinase C, and that exaggerated responsiveness to protein kinase A is observed in the partially denervated striatum.

Research paper thumbnail of 1,1,3 Tricyano-2-amino-1-propene (Triap): a small molecule which mimics or potentiates nerve growth factor

Developmental Brain Research, 1990

1,1,3 Tricyano-2-amino-l-propene (Trlap) is a small molecular weight compound which increases the... more 1,1,3 Tricyano-2-amino-l-propene (Trlap) is a small molecular weight compound which increases the rate of nerve and tissue regeneration m several experimental systems Early experiments with this compound showed that, like nerve growth factor (NGF), Trlap induced neurite formation in chick spinal ganglia To assess the similarity between NGF and Triap, we compared the effects of Triap and NGF on a rat pheochromocytoma cell line (PC12) and on cell survival in a primary chick neuronal culture In the latter, Triap at ~<0 01 nM preserved neurons and caused them to extend neurites as did 1 nM NGF Triap induced neurlte outgrowth in the PC12 cell hne giving a maximal response (40-50% of the maximal response of NGF) at a concentration of 20/~g/ml (151/~M) Triap's morphological effects were not inhibited by antibodies directed against NGF or the NGF receptor Low concentrations of Triap also potentiated the morphological effects of NGF Triap induced an increase in cell-substratum adhesion and cellular hypertrophy in PC12 cells and also potentiated the adhesive actions of NGF Tnap had no effect on ornithine decarboxylase activity even though it potentiated NGF's effects on this enzyme These data indicate that Trlap reduces neurotrophlc effects and does not seem to act through the same mechanisms as NGF but can potentiate many of NGF's morphological and biochemical actions

Research paper thumbnail of Hydra head activator peptide has trophic activity for eukaryotic neurons

Developmental Brain Research, 1992

The synthetic undecameric peptide, pGlu-Pro-Pro-Gly-Gly-Ser-Lys-Val-Ile-Leu-Phe, known as the hyd... more The synthetic undecameric peptide, pGlu-Pro-Pro-Gly-Gly-Ser-Lys-Val-Ile-Leu-Phe, known as the hydra head activator peptide, present in high concentrations in mammalian hypothalamus and intestine, was tested for neurotrophic activity in a survival assay using cultured chick embryonic sympathetic and dorsal root ganglion cells, and for morphological differentiation activity on neuroblastoma cells. Hydra head activator peptide supported neuron survival. The optimal active concentration, 1 pM, was very similar to the concentration that causes bud and head formation in hydra. Maximal neuron survival obtained with hydra head activator peptide was close to that obtained with nerve growth factor: both substances enhanced survival up to 3 times that of control cultures. Bradykinin, which has some amino acid sequence homology with hydra head activator, was inactive as a neurotrophic factor. Hydra head activator induced rapid morphological differentiation of the mouse neuroblastoma cell line Neuro-2A. Neuro-2A responded to the peptide by process extension, 4 h after its addition to the culture medium. Neurotrophic factors isolated to date have been characterized by their ability to maintain cell viability and enhance neurite outgrowth. Hydra head activator peptide met these two criteria when tested in 3 different neuron culture systems. Our results suggest that the head activator peptide may act as a neurotrophic factor for neurons in other species, including mammals.

Research paper thumbnail of Expression of neurotrophic activity in Xenopus oocytes injected with mRNA from wounded rat cerebral cortex

Molecular Brain Research, 1990

Injury to the cerebral cortex of the rat brain has been shown to induce the expression of neurotr... more Injury to the cerebral cortex of the rat brain has been shown to induce the expression of neurotrophic factors for dissociated peripheral and central neurons in culture. We confirm this phenomenon and report that Xenopus laevis oocytes injected with mRNA extracted from wounded rat cortex expressed similar neurotrophic activity. To detect the low amounts of neurotrophic factors that could be expected from the oocyte translation system, a miniaturization of the assay for neurotrophic and cell-surviving activity was developed using Terasaki microtiter plates for culture of chicken embryo sympathetic ganglion cells. Messenger RNA (mRNA) was size-fractionated on a sucrose gradient and RNAs from each fraction were injected into oocytes. Neurotrophic activity was recovered from the homogenates and from the incubation media of oocytes injected with mRNA from 7 day post-lesion cortex. Messenger RNAs in the active fractions ranged in size from 0.8 to 1.8 kb. As much as 20% of the activity was secreted by the oocytes. No significant neurotrophic activity was detected from oocytes injected with mRNA fractions extracted from the cortex of control rats or from other gradient fractions from post-lesion cortex.

Research paper thumbnail of Tyrosine hydroxylase, aromatic l-amino acid decarboxylase and dopamine metabolism after chronic treatment with dopaminergic drugs

Brain Research, 1999

1H-3-benzazepine-7,8-diol DA D-like ; bromocriptine, DA D selective ; quinpirole, DA D rD preferr... more 1H-3-benzazepine-7,8-diol DA D-like ; bromocriptine, DA D selective ; quinpirole, DA D rD preferring ; "-7-2 1 patterns of change did not follow those for TH or AAAD. When studied 48 h after the last dose of the chronic haloperidol schedule TH displayed tolerance to acute drug challenge. At the same time interval, there was tolerance to the enhancing effects of haloperidol and SCH 23390 on DA metabolism. The induction of AAAD by haloperidol or SCH 23990 did not appear to develop tolerance after chronic administration. These observations complement existing knowledge, and provide novel information about AAAD that may have practical importance for Parkinson's patients on L-DOPA therapy.