Giancarlo Pepeu - Academia.edu (original) (raw)
Papers by Giancarlo Pepeu
NeuroReport, 1999
The effect of the adenosine A2A receptor agonist CGS 21680 on glutamate and aspartate release was... more The effect of the adenosine A2A receptor agonist CGS 21680 on glutamate and aspartate release was investigated in the striatum of young and old rats by microdialysis experiments. CGS 21680 (10 microM) significantly increased glutamate and aspartate spontaneous outflow in young but not in old rats. On the contrary, CGS 21680 induced the same decrease in K+-evoked glutamate outflow in both young and aged rats. A lower dose of CGS 21680 (1 microM) failed to modify either spontaneous or K+-evoked outflow. It is suggested that the opposite effects of the A2A agonist on excitatory amino acid outflow may be respectively mediated by striatal A2A adenosine receptors located on glutamatergic terminals and on the striatal indirect output pathway.
Progress in Brain Research, 1990
Publisher Summary This chapter discusses the principal aspects of the regulation of acetylcholine... more Publisher Summary This chapter discusses the principal aspects of the regulation of acetylcholine (ACh) release in the brain. The study of ACh release coupled with the recording of neuronal activity and the study of behavior is the most direct approach to understand the role of central cholinergic neurons; identifying metabolic conditions, neurotransmitters, and drugs that may modify their activity. The cholinergic neurons and their fibers are always mixed with noncholinergic neurons. The ACh release from many nerve endings is collected to quantify it, relatively large brain regions, also containing many noncholinergic nerve endings, are required, and irrespective of the procedure used for measuring ACh release. Thus, correlations between electrical activity of specific neuronal pathways and ACh release become approximate. Similarly approximate is the correlation between ACh release and the behavior. The chapter reviews the conditions influencing ACh release in the brain and is illustrated by examples taken from in vivo and in vitro studies. The methods that are used for studying ACh release in the brain are presented in the chapter.
Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1986
A review of the work on the neurochemical, electroencephalographic and behavioral changes induced... more A review of the work on the neurochemical, electroencephalographic and behavioral changes induced in the rat by lesions of the nucleus basalis is presented. The similarities and differences between the effects of the lesions and the neurochemical and clinical alterations characterizing senile dementia of Alzheimer type are pointed out. The decrease in choline acetyltransferase (ChAT) activity in the cortex following unilateral or bilateral electrolytic or neurotoxic lesions of the nucleus basalis are described and compared with the decrease in ChAT activity found in the cortex and hippocampus of patients affected by senile dementia. At variance with the latter condition, in rats with lesions of the nucleus basalis a spontaneous recovery in cortical ChAT activity has been observed 3-6 months after the lesion. The lesions of the nucleus basalis decrease high affinity choline uptake activity which, however, undergoes a rapid recovery. Lesions also decrease spontaneous and drug-stimulated ACh release from the cerebral cortex. Transitory changes in the number of muscarinic binding sites have been reported in the cerebral cortex of the lesioned rats while a decrease in the number of muscarinic binding sites has generally been found in the cerebral cortex of patients with senile dementia. [3H] glutamate uptake in the striatum of the lesioned rats was not affected. In both lesioned rats and patients affected by senile dementia, a decrease of low voltage high frequency electrocortical activity has been reported. Unilateral and bilateral lesions of the nucleus basalis bring about an impairment of the acquisition of active and passive avoidance responses and of the rewarded alternation discriminatory tasks involving working memory and spatial memory. On the other hand, memory impairment is a typical symptom of senile dementia. In conclusion, the lesions of the nucleus basalis only partly mimic the complex clinical picture of senile dementia of Alzheimer type. They offer, nevertheless, a useful tool for understanding the critical role of the central cholinergic pathways in some of the cognitive processes and identifying potentially useful pharmacological treatments.
Psychopharmacology, 1999
Abstract Rationale: Caffeine is a non-selective A 1/A 2 adenosine receptor antagonist which is kn... more Abstract Rationale: Caffeine is a non-selective A 1/A 2 adenosine receptor antagonist which is known to improve cognitive performance in humans. This effect of caffeine has been attributed to its antagonism of adenosine receptors. Objective: The present study was ...
Neuroscience, 1997
Brain acetylcholine release and memory performance were investigated in young (three- to six-mont... more Brain acetylcholine release and memory performance were investigated in young (three- to six-months) and old (20- to 24-months) rats. Acetylcholine release was measured in vivo in the cortex and hippocampus of freely-moving animals, under basal conditions and in the presence of the following muscarinic antagonists: scopolamine, (±)-5,11-dihydro-11-{[(2-[2-[(dipropylamino) methyl]-1-piperidinyl} ethyl) amino] carbonyl}-6H-pyrido(2,3-b)(1,4)-benzodiazepine-6-one (AFDX 384) and pirenzepine. The amount of acetylcholine released
Neuroscience, 1998
The long-term effects of-amyloid peptide 1-40 injection into the rat forebrain were studied. Ten ... more The long-term effects of-amyloid peptide 1-40 injection into the rat forebrain were studied. Ten micrograms of pre-aggregated peptide were injected into the right nucleus basalis of male Wistar rats which were then killed four or six months later. Congo Red staining of histological sections showed that the peptide deposit was aggregated in a fibrillary form four months post-surgery, whereas at six months almost no trace of birefringency was detected at the deposit site, indicating a loss of fibril organization. This result was confirmed by electron microscopic analysis of the peptide deposits. The presence of the peptide at the injection site six months post-surgery was demonstrated by both Haematoxylin staining and-amyloid immunoreactivity. The number of choline acetyltransferase-immunoreactive neurons was reduced by 66% in the injected nucleus basalis four months after injection. A decrease in cortical acetylcholine release was also found at this time. Concomitantly with the loss of fibril conformation, a complete recovery of choline acetyltransferase immunoreactivity in the nucleus basalis and of acetylcholine release in the cortex was observed at six months. These data provide in vivo evidence that-amyloid neurotoxicity is related to the fibrillary conformation of the peptide aggregates, thus confirming previous in vitro studies. 1998 IBRO. Published by Elsevier Science Ltd.
Neurobiology of Disease, 2002
Injection into the nucleus basalis of the rat of preaggregated A(1-42) produced a congophylic de... more Injection into the nucleus basalis of the rat of preaggregated A(1-42) produced a congophylic deposit and microglial and astrocyte activation and infiltration and caused a strong inflammatory reaction characterized by IL-1 production, increased inducible cyclooxygenase (COX-2), and inducible nitric oxide synthase (iNOS) expression. Many phospho-p38MAPK-positive cells were observed around the deposit at 7 days after A injection. Phospho-p38MAPK colocalized with activated microglial cells, but not astrocytes. The inflammatory reaction was accompanied by cholinergic hypofunction. We investigated the protective effect of the selective COX-2 inhibitor rofecoxib in attenuating the inflammatory response and neurodegeneration evoked by A(1-42). Rofecoxib (3 mg/kg/day, 7 days) reduced microglia and astrocyte activation, iNOS induction, and p38MAPK activation to control levels. Cholinergic hypofunction was also significantly attenuated by treatment with rofecoxib. We show here for the first time in vivo the pivotal role played by the p38MAPK microglial signal transduction pathway in the inflammatory response to the A(1-42) deposit.
Neurobiology of Aging, 2002
To evaluate whether inflammation-like mechanisms present in the brain of Alzheimer's disease (AD)... more To evaluate whether inflammation-like mechanisms present in the brain of Alzheimer's disease (AD) patients are reflected in the periphery, the expression of CD11b in peripheral blood neutrophils and the expression and activity of inflammatory markers in cultured skin fibroblasts were examined. We found significantly higher levels of CD11b in neutrophils from sporadic AD patients than in controls and this elevation was positively correlated with disease severity and progression rate of mental decline. Cultured skin fibroblasts from familial (FAD) and sporadic AD patients and from controls were immunopositive for both isoforms of cyclooxygenase with no differences between groups. In unstimulated culture, the production of prostaglandin-E2 in the medium was significantly higher in fibroblasts from sporadic AD and FAD patients than in controls, and this elevation was reverted by the addition of 25 M of ibuprofen. Our findings provide further evidence of the presence of inflammatory and immuno-related markers in the periphery of AD patients and support those studies indicating the beneficial effects of anti-inflammatory therapy in AD.
Journal of Neuroscience Research, 1984
The effect of repeated administrations of GM1 monosialoganglioside on high-affinity choline uptak... more The effect of repeated administrations of GM1 monosialoganglioside on high-affinity choline uptake (HACU) was investigated in the cerebral cortex of rats with a unilateral electrolytic lesion of the nucleus basalis magnocellularis. In saline-treated rats, 4 days after lesion, a 38% and 14% decrease in HACU-activity was found in the ipsilateral frontal and parietal cortex, respectively. A spontaneous recovery of HACU activity occurred within the next 20 days. In rats receiving daily injections of GM1 from the day of operation, no significant decrease in HACU activity was found in the lesioned hemisphere 4 days after the lesion. In contrast a 25% increase in HACU activity in the frontal area of the opposite hemisphere was detected. No effect of GM1 treatment could be seen on days 10 or 20 after lesion. The possibility that GM1 may exert its stimulatory effect on HACU independently of the well-known effect of gangliosides on neuronal sprouting is discussed.
European Journal of Pharmacology, 1994
The adenosine concentration in samples of perfusate was determined 24 h after implantation of mic... more The adenosine concentration in samples of perfusate was determined 24 h after implantation of microdialysis fibre in the cortex. High performance liquid chromatography coupled with a fluorometric detector was used. K ÷ (100 mM) depolarization was followed by a 2-to 4-fold increase in adenosine effiux. The addition of tetrodotoxin (1/zM) to the perfusate was followed by a decrease in spontaneous and K+-evoked adenosine effiux. The increase induced by high K ÷ was markedly inhibited by the NMDA receptor antagonist, o(-)-2-amino-7-phosphonoheptanoic acid (1 mM, D-AP7), but not by the muscarinic receptor antagonist, atropine (1.5/xM). The acetylcholine esterase inhibitor, physostigmine (7/zM), and the muscarinic receptor agonist, oxotremorine (100/zM), significantly enhanced the K+-evoked increase in adenosine. The spontaneous efflux of adenosine was not modified by any of the drugs tested. A neurotoxic lesion of the cholinergic pathway innervating the cortex, although inducing a marked decrease in cortical choline acetyltransferase activity, did not significantly modify the cortical adenosine efflux. It is concluded that, under K+-depolarizing conditions, adenosine effiux is triggered by excitatory amino acids and enhanced by muscarinic activation.
European Journal of Neuroscience, 2000
Brain in¯ammatory processes underlie the pathogenesis of Alzheimer's disease, and nonsteroidal an... more Brain in¯ammatory processes underlie the pathogenesis of Alzheimer's disease, and nonsteroidal anti-in¯ammatory drugs have a protective effect in the disease. The aim of this study was to characterize in vivo in the rat brain the in¯ammatory reaction in response to excitotoxic insult and to investigate the ef®cacy of nimesulide treatment. Quisqualic acid was injected into the right nucleus basalis of rats. The excitotoxin induced cholinergic degeneration, an intense glial reaction and the production of in¯ammatory mediators. Three hours after injection, a ®ve-fold elevation in the concentration of interleukin-1b in the injected area was observed. This elevation was reduced by 50% by nimesulide (10 mg/kg, i.m.) pretreatment. Electron microscope examination and immunocytochemical staining revealed an intense activation of microglia and astrocytes at both 24 h and 7 days after injection. Cyclooxygenase-2immunoreactivity was induced in the blood vessels of the injected hemisphere in perivascular microglial and endothelial cells 24 h after injection. Seven days postinjection, a cyclooxygenase-2-positive signal was induced in the parenchymal microglia and large amounts of prostaglandin-E 2 were measured in the injected area. Twenty-four hours and 7 days after injection, many inducible nitric oxide synthase-positive cells and a high level of nitrite were detected at the injection site. Seven days of nimesulide (10 mg/kg/day, i.m.) treatment strongly attenuated the microglial reaction, reduced the number of inducible nitric oxide synthase-positive cells and completely abolished the increase in prostaglandin-E 2 formation. These data provide valuable support in vivo for the potential ef®cacy of cyclooxygenase-2 inhibitors in Alzheimer's disease therapy.
Brain Research, 1982
High affinity choline uptake (HACU) and chohne acetyltransferase (CAT) were measured in the cereb... more High affinity choline uptake (HACU) and chohne acetyltransferase (CAT) were measured in the cerebral cortex of rats 4 and 20 days after placing electrolytic lesions in the magnocellular forebrain nuclei (MFN) or in the pallidum. Four days after MFN lesion a 40-50% decrease in ipsilateral corucal HACU was found and a slightly smaller decrease was found 4 days after the pallidum lesion. Twenty days after the lesion, HACU activity returned to control values in the ipsilateral parietal cortex, its decrease was smaller than 4 days postlesion in the ipsilateral frontal cortex and a significant increase was found in the contralateral cortex. CAT activity showed a 40% decrease in the frontal, parietal and occipital ipsilateral cortex 4 days after MFN lesion. The same decrease was found 20 da~s postlesion. However, at this time a significant increase in CAT activity was detected in the contralateral cortex. The ipsilateral recovery of HACU activity 20 days after the lesions and the contralaterai increase in HACU and CAT activity demonstrate the remarkable and widespread functional adjustment associated with discrete brain lesions. The existence of a large cholinergic pathway projecting to the neocortex from the basaI forebram region is also confirmed.
Brain Research, 1985
The effects of GM 1 ganglioside (30 mg/kg i.p.) administration for 22 days on choline acetyltrans... more The effects of GM 1 ganglioside (30 mg/kg i.p.) administration for 22 days on choline acetyltransferase (CHAT) activity and noradrenaline (NA) levels in the cerebral cortex and on the acquisition of active and passive avoidance-conditioned responses were investigated in both sham-operated rats and in rats with a unilateral electrolytic lesion of the magnocellular forebrain nuclei (MFN). A statistically significant ChAT decrease in cortical areas ipsilateral to the lesion was found in saline-treated lesioned rats. In the lesioned GMl-treated rats, ChAT activity was only reduced in the frontoparietal areas and was significantly increased in the ipsilateral parietooccipital areas as well as in both contralateral regions. NA levels in the cortex were neither significantly affected by the lesion nor by GM 1 treatment. The lesion impaired the acquisition of active and passive conditioned avoidance responses. GM1 treatment improved acquisition of the active avoidance response in the lesioned rats as indicated by a larger number of avoidances and a smaller number of escape failures during training in comparison with saline treatment. Ganglioside had no effect on the passive avoidance responses. These results demonstrate that GM 1 administration facilitates the recovery of the cortical cholinergic system and of behavioral responses impaired by an electrolytic lesion of the cholinergic forebrain nuclei.
Behavioural Pharmacology, 1995
Pharmacological Research, 1990
Naunyn Schmiedeberg S Archives of Pharmacology, 1990
Annali dell'Istituto superiore di sanità, 1988
General Pharmacology: The Vascular System, 1996
Adenosine is an endogenous neuromodulator that exerts its depressant effect on neurons by acting ... more Adenosine is an endogenous neuromodulator that exerts its depressant effect on neurons by acting on the A, adenosine receptor subtype. Excitatory actions of adenosine, mediated by the activation of the Az adenosine receptor subtype, have also been shown in the central nervous system. 2. Adenosine Az, receptors are highly localized in the striatum, as demonstrated by the binding assay of the Aza selective agonist, CGS2680, and by analysis of the A2 receptor mRNA localization with in situ hybridization histochemistry. However, adenosine Az, receptors, albeit at lower levels, are also localized in other brain regions, such as the cortex and the hippocampus. 3. In the striatum, adenosine A2, receptors are implicated in the control of motor activity. Evidences exists of an antagonistic interaction between adenosine A2, and dopamine Dz receptors. 4. Utilizing selective agonists and antagonists for adenosine Az, receptors, their role in the modulation of the release of several neurotransmitters (acetylcholine, dopamine, glutamate, GABA) has been extensively studied in the brain (striatum, cortex, hippocampus). Controversial results have been obtained and, because the overall effect of endogenous adenosine in the brain is that of an inhibitory tonus, the physiological meaning of the excitatory A2 receptor remains to be clarified. GEN PHARMAC 27;6:925-933, 1996 KEY WORDS. Adenosine, central nervous system, S. Latini et al. (2-CADO)>N-ethylcarboxamidoadenosine (NECA) > S-PIA > 2-(phenylamino)adenosine (CV1808), and for the A2 receptor is: 2-[[2-[4-(2-carboxyethyl)phenyl]ethyl]amino]-N-ethylcarboxamidoadenosine (CGS21680) =NECA> 2-CADO>CV 1808 =R-PIA> CPA=CHA>S-PIA (Williams, 1990). Recently, new adenosine agonists, such as 2-chloro-N6-cyclopentyladenosine (CCPA), with high affinity (Ki=0.4 nM) and selectivity (about 10,000-fold) for A~ receptors (Lohse et al., 1988b), and 2-hexynyl-NECA with high affinity (/(,=3.8 nM) and selectivity for A2 vs AI receptors, on the order of 12-fold, have been described (Cristalli et al., 1992). Both classes of adenosine receptors can be antagonized by xanthine compounds, such as caffeine, theophylline and related 8-phenylxanthines. More recently, a number of selective xanthine antagonists, such as 8-cyclopenthyl-l,3-dipropylxanthine (DPCPX) for A~ receptors (Ki=0.5 nM; AdAl =700) (Bruns etal., 1987b; Lohse et al., 1987), (E)-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-methylxanthine (KF17837) (K,=I.0 nM; AI/A2=62) (Nonaka et al., 1994), and 8-(3-chlorostyryl)caffeine (CSC) (K=54 nM; AI/A:=518) (Jacobson et al., 1993) for A2 receptors, have been developed. Several non-xanthine antagonists selective for A2 receptors, but with low water solubility, such as 4-amino-8-chloro-1-phenyl[1,2,4]triazolo[4,3-e~]quinoxaline (CP66713) (K, = 12 nM; AI/A2 = 13.0) (Sarges eta/., 1990), and 9-chloro-2-(2-furanyl)-5,6-dihydro-1,2,4-triazolo[1,5-c]quinazoline-5-imine (CGS15943A) (K=4 nM; At/A2=6) (Jarvis et al., 1991), have also recently been described. These compounds are useful in the characterization of A~ and A2 receptor subtypes. A sub-classification of the A~ receptor into A~.~, with high affinity for agonists and located in the central nervous system, and A~b, with low affinity and located in the peripheral nervous system, has been proposed (Gustafsson et al., 1990). However, there is currently no evidence at the molecular level to support the existence of A~, and A,~ receptors. A~ receptors have also been subclassified into A2,, a high-affinity receptor highly localized in the striatum, and A21~, a low-affinity receptor that exists in ahnost all areas of the brain (Bruns et al., 1986). Compounds such as CV1808 and CGS21680 have been developed that show high affinity for the rat striatal A,,, receptor (Bruns et al., 1986; Jarvis et al., 1989b), and could be used to differentiate A:, from either A> or A~ receptors. Adenosine A2~, and A2b receptors have also been cloned from several animal species (Linden et al., 1994). Recently, another adenosine receptor, termed A~, has been cloned in the rat brain (Zhou et al., 1992). Although this name was previously used by Ribeiro and Sebastiao (1986) to indicate a presynaptic adenosine receptor at the neuromuscular junction of the frog sartorius muscle, there seems to be no relationship between this and the cloned receptor. An adenosine receptor, termed A4, has been characterized in rat brain tissue using CV1808 (Cornfield et al., 1992), but it has not yet been cloned. Thus, the original AI and A., receptor classification has been extended, because to date 4 distinct adenosine receptors (AI, A~,~,, A2b, A~) have been cloned from a variety of mammalian species (see Table 1). LOCALIZATION OF ADENOSINE Az RECEPTORS IN THE BRAIN The distribution of adenosine receptor subtypes in the mammalian brain has been extensively studied (Goodman and Snyder, 1982; Jarvis, 1988). Adenosine A1 receptors have been well characterized by using binding assays (
Neurobiology of Acetylcholine, 1987
Histochemical and neurochemical investigations demonstrate that the mammalian cerebral cortex con... more Histochemical and neurochemical investigations demonstrate that the mammalian cerebral cortex contains a diffuse cholinergic network formed prevalently by nerve endings whose somata are located in the basal forebrain nuclei (Mesulam et al., 1983; Wainer et al., 1984). Minor contributions to the cortical cholinergic network are due to a direct projection from the large choline acetyltransferase (ChAT) immunoreactive cells in the pontomesencephalon (Mesulam et al., 1983) and, in the rat, by interneurons scattered throughout all cellular layers in all cortices which contain approximately 30% of total ChAT (Levey et al., 1984; McGeer et al., 1984).
Pharmacological Research, 1990
NeuroReport, 1999
The effect of the adenosine A2A receptor agonist CGS 21680 on glutamate and aspartate release was... more The effect of the adenosine A2A receptor agonist CGS 21680 on glutamate and aspartate release was investigated in the striatum of young and old rats by microdialysis experiments. CGS 21680 (10 microM) significantly increased glutamate and aspartate spontaneous outflow in young but not in old rats. On the contrary, CGS 21680 induced the same decrease in K+-evoked glutamate outflow in both young and aged rats. A lower dose of CGS 21680 (1 microM) failed to modify either spontaneous or K+-evoked outflow. It is suggested that the opposite effects of the A2A agonist on excitatory amino acid outflow may be respectively mediated by striatal A2A adenosine receptors located on glutamatergic terminals and on the striatal indirect output pathway.
Progress in Brain Research, 1990
Publisher Summary This chapter discusses the principal aspects of the regulation of acetylcholine... more Publisher Summary This chapter discusses the principal aspects of the regulation of acetylcholine (ACh) release in the brain. The study of ACh release coupled with the recording of neuronal activity and the study of behavior is the most direct approach to understand the role of central cholinergic neurons; identifying metabolic conditions, neurotransmitters, and drugs that may modify their activity. The cholinergic neurons and their fibers are always mixed with noncholinergic neurons. The ACh release from many nerve endings is collected to quantify it, relatively large brain regions, also containing many noncholinergic nerve endings, are required, and irrespective of the procedure used for measuring ACh release. Thus, correlations between electrical activity of specific neuronal pathways and ACh release become approximate. Similarly approximate is the correlation between ACh release and the behavior. The chapter reviews the conditions influencing ACh release in the brain and is illustrated by examples taken from in vivo and in vitro studies. The methods that are used for studying ACh release in the brain are presented in the chapter.
Progress in Neuro-Psychopharmacology and Biological Psychiatry, 1986
A review of the work on the neurochemical, electroencephalographic and behavioral changes induced... more A review of the work on the neurochemical, electroencephalographic and behavioral changes induced in the rat by lesions of the nucleus basalis is presented. The similarities and differences between the effects of the lesions and the neurochemical and clinical alterations characterizing senile dementia of Alzheimer type are pointed out. The decrease in choline acetyltransferase (ChAT) activity in the cortex following unilateral or bilateral electrolytic or neurotoxic lesions of the nucleus basalis are described and compared with the decrease in ChAT activity found in the cortex and hippocampus of patients affected by senile dementia. At variance with the latter condition, in rats with lesions of the nucleus basalis a spontaneous recovery in cortical ChAT activity has been observed 3-6 months after the lesion. The lesions of the nucleus basalis decrease high affinity choline uptake activity which, however, undergoes a rapid recovery. Lesions also decrease spontaneous and drug-stimulated ACh release from the cerebral cortex. Transitory changes in the number of muscarinic binding sites have been reported in the cerebral cortex of the lesioned rats while a decrease in the number of muscarinic binding sites has generally been found in the cerebral cortex of patients with senile dementia. [3H] glutamate uptake in the striatum of the lesioned rats was not affected. In both lesioned rats and patients affected by senile dementia, a decrease of low voltage high frequency electrocortical activity has been reported. Unilateral and bilateral lesions of the nucleus basalis bring about an impairment of the acquisition of active and passive avoidance responses and of the rewarded alternation discriminatory tasks involving working memory and spatial memory. On the other hand, memory impairment is a typical symptom of senile dementia. In conclusion, the lesions of the nucleus basalis only partly mimic the complex clinical picture of senile dementia of Alzheimer type. They offer, nevertheless, a useful tool for understanding the critical role of the central cholinergic pathways in some of the cognitive processes and identifying potentially useful pharmacological treatments.
Psychopharmacology, 1999
Abstract Rationale: Caffeine is a non-selective A 1/A 2 adenosine receptor antagonist which is kn... more Abstract Rationale: Caffeine is a non-selective A 1/A 2 adenosine receptor antagonist which is known to improve cognitive performance in humans. This effect of caffeine has been attributed to its antagonism of adenosine receptors. Objective: The present study was ...
Neuroscience, 1997
Brain acetylcholine release and memory performance were investigated in young (three- to six-mont... more Brain acetylcholine release and memory performance were investigated in young (three- to six-months) and old (20- to 24-months) rats. Acetylcholine release was measured in vivo in the cortex and hippocampus of freely-moving animals, under basal conditions and in the presence of the following muscarinic antagonists: scopolamine, (±)-5,11-dihydro-11-{[(2-[2-[(dipropylamino) methyl]-1-piperidinyl} ethyl) amino] carbonyl}-6H-pyrido(2,3-b)(1,4)-benzodiazepine-6-one (AFDX 384) and pirenzepine. The amount of acetylcholine released
Neuroscience, 1998
The long-term effects of-amyloid peptide 1-40 injection into the rat forebrain were studied. Ten ... more The long-term effects of-amyloid peptide 1-40 injection into the rat forebrain were studied. Ten micrograms of pre-aggregated peptide were injected into the right nucleus basalis of male Wistar rats which were then killed four or six months later. Congo Red staining of histological sections showed that the peptide deposit was aggregated in a fibrillary form four months post-surgery, whereas at six months almost no trace of birefringency was detected at the deposit site, indicating a loss of fibril organization. This result was confirmed by electron microscopic analysis of the peptide deposits. The presence of the peptide at the injection site six months post-surgery was demonstrated by both Haematoxylin staining and-amyloid immunoreactivity. The number of choline acetyltransferase-immunoreactive neurons was reduced by 66% in the injected nucleus basalis four months after injection. A decrease in cortical acetylcholine release was also found at this time. Concomitantly with the loss of fibril conformation, a complete recovery of choline acetyltransferase immunoreactivity in the nucleus basalis and of acetylcholine release in the cortex was observed at six months. These data provide in vivo evidence that-amyloid neurotoxicity is related to the fibrillary conformation of the peptide aggregates, thus confirming previous in vitro studies. 1998 IBRO. Published by Elsevier Science Ltd.
Neurobiology of Disease, 2002
Injection into the nucleus basalis of the rat of preaggregated A(1-42) produced a congophylic de... more Injection into the nucleus basalis of the rat of preaggregated A(1-42) produced a congophylic deposit and microglial and astrocyte activation and infiltration and caused a strong inflammatory reaction characterized by IL-1 production, increased inducible cyclooxygenase (COX-2), and inducible nitric oxide synthase (iNOS) expression. Many phospho-p38MAPK-positive cells were observed around the deposit at 7 days after A injection. Phospho-p38MAPK colocalized with activated microglial cells, but not astrocytes. The inflammatory reaction was accompanied by cholinergic hypofunction. We investigated the protective effect of the selective COX-2 inhibitor rofecoxib in attenuating the inflammatory response and neurodegeneration evoked by A(1-42). Rofecoxib (3 mg/kg/day, 7 days) reduced microglia and astrocyte activation, iNOS induction, and p38MAPK activation to control levels. Cholinergic hypofunction was also significantly attenuated by treatment with rofecoxib. We show here for the first time in vivo the pivotal role played by the p38MAPK microglial signal transduction pathway in the inflammatory response to the A(1-42) deposit.
Neurobiology of Aging, 2002
To evaluate whether inflammation-like mechanisms present in the brain of Alzheimer's disease (AD)... more To evaluate whether inflammation-like mechanisms present in the brain of Alzheimer's disease (AD) patients are reflected in the periphery, the expression of CD11b in peripheral blood neutrophils and the expression and activity of inflammatory markers in cultured skin fibroblasts were examined. We found significantly higher levels of CD11b in neutrophils from sporadic AD patients than in controls and this elevation was positively correlated with disease severity and progression rate of mental decline. Cultured skin fibroblasts from familial (FAD) and sporadic AD patients and from controls were immunopositive for both isoforms of cyclooxygenase with no differences between groups. In unstimulated culture, the production of prostaglandin-E2 in the medium was significantly higher in fibroblasts from sporadic AD and FAD patients than in controls, and this elevation was reverted by the addition of 25 M of ibuprofen. Our findings provide further evidence of the presence of inflammatory and immuno-related markers in the periphery of AD patients and support those studies indicating the beneficial effects of anti-inflammatory therapy in AD.
Journal of Neuroscience Research, 1984
The effect of repeated administrations of GM1 monosialoganglioside on high-affinity choline uptak... more The effect of repeated administrations of GM1 monosialoganglioside on high-affinity choline uptake (HACU) was investigated in the cerebral cortex of rats with a unilateral electrolytic lesion of the nucleus basalis magnocellularis. In saline-treated rats, 4 days after lesion, a 38% and 14% decrease in HACU-activity was found in the ipsilateral frontal and parietal cortex, respectively. A spontaneous recovery of HACU activity occurred within the next 20 days. In rats receiving daily injections of GM1 from the day of operation, no significant decrease in HACU activity was found in the lesioned hemisphere 4 days after the lesion. In contrast a 25% increase in HACU activity in the frontal area of the opposite hemisphere was detected. No effect of GM1 treatment could be seen on days 10 or 20 after lesion. The possibility that GM1 may exert its stimulatory effect on HACU independently of the well-known effect of gangliosides on neuronal sprouting is discussed.
European Journal of Pharmacology, 1994
The adenosine concentration in samples of perfusate was determined 24 h after implantation of mic... more The adenosine concentration in samples of perfusate was determined 24 h after implantation of microdialysis fibre in the cortex. High performance liquid chromatography coupled with a fluorometric detector was used. K ÷ (100 mM) depolarization was followed by a 2-to 4-fold increase in adenosine effiux. The addition of tetrodotoxin (1/zM) to the perfusate was followed by a decrease in spontaneous and K+-evoked adenosine effiux. The increase induced by high K ÷ was markedly inhibited by the NMDA receptor antagonist, o(-)-2-amino-7-phosphonoheptanoic acid (1 mM, D-AP7), but not by the muscarinic receptor antagonist, atropine (1.5/xM). The acetylcholine esterase inhibitor, physostigmine (7/zM), and the muscarinic receptor agonist, oxotremorine (100/zM), significantly enhanced the K+-evoked increase in adenosine. The spontaneous efflux of adenosine was not modified by any of the drugs tested. A neurotoxic lesion of the cholinergic pathway innervating the cortex, although inducing a marked decrease in cortical choline acetyltransferase activity, did not significantly modify the cortical adenosine efflux. It is concluded that, under K+-depolarizing conditions, adenosine effiux is triggered by excitatory amino acids and enhanced by muscarinic activation.
European Journal of Neuroscience, 2000
Brain in¯ammatory processes underlie the pathogenesis of Alzheimer's disease, and nonsteroidal an... more Brain in¯ammatory processes underlie the pathogenesis of Alzheimer's disease, and nonsteroidal anti-in¯ammatory drugs have a protective effect in the disease. The aim of this study was to characterize in vivo in the rat brain the in¯ammatory reaction in response to excitotoxic insult and to investigate the ef®cacy of nimesulide treatment. Quisqualic acid was injected into the right nucleus basalis of rats. The excitotoxin induced cholinergic degeneration, an intense glial reaction and the production of in¯ammatory mediators. Three hours after injection, a ®ve-fold elevation in the concentration of interleukin-1b in the injected area was observed. This elevation was reduced by 50% by nimesulide (10 mg/kg, i.m.) pretreatment. Electron microscope examination and immunocytochemical staining revealed an intense activation of microglia and astrocytes at both 24 h and 7 days after injection. Cyclooxygenase-2immunoreactivity was induced in the blood vessels of the injected hemisphere in perivascular microglial and endothelial cells 24 h after injection. Seven days postinjection, a cyclooxygenase-2-positive signal was induced in the parenchymal microglia and large amounts of prostaglandin-E 2 were measured in the injected area. Twenty-four hours and 7 days after injection, many inducible nitric oxide synthase-positive cells and a high level of nitrite were detected at the injection site. Seven days of nimesulide (10 mg/kg/day, i.m.) treatment strongly attenuated the microglial reaction, reduced the number of inducible nitric oxide synthase-positive cells and completely abolished the increase in prostaglandin-E 2 formation. These data provide valuable support in vivo for the potential ef®cacy of cyclooxygenase-2 inhibitors in Alzheimer's disease therapy.
Brain Research, 1982
High affinity choline uptake (HACU) and chohne acetyltransferase (CAT) were measured in the cereb... more High affinity choline uptake (HACU) and chohne acetyltransferase (CAT) were measured in the cerebral cortex of rats 4 and 20 days after placing electrolytic lesions in the magnocellular forebrain nuclei (MFN) or in the pallidum. Four days after MFN lesion a 40-50% decrease in ipsilateral corucal HACU was found and a slightly smaller decrease was found 4 days after the pallidum lesion. Twenty days after the lesion, HACU activity returned to control values in the ipsilateral parietal cortex, its decrease was smaller than 4 days postlesion in the ipsilateral frontal cortex and a significant increase was found in the contralateral cortex. CAT activity showed a 40% decrease in the frontal, parietal and occipital ipsilateral cortex 4 days after MFN lesion. The same decrease was found 20 da~s postlesion. However, at this time a significant increase in CAT activity was detected in the contralateral cortex. The ipsilateral recovery of HACU activity 20 days after the lesions and the contralaterai increase in HACU and CAT activity demonstrate the remarkable and widespread functional adjustment associated with discrete brain lesions. The existence of a large cholinergic pathway projecting to the neocortex from the basaI forebram region is also confirmed.
Brain Research, 1985
The effects of GM 1 ganglioside (30 mg/kg i.p.) administration for 22 days on choline acetyltrans... more The effects of GM 1 ganglioside (30 mg/kg i.p.) administration for 22 days on choline acetyltransferase (CHAT) activity and noradrenaline (NA) levels in the cerebral cortex and on the acquisition of active and passive avoidance-conditioned responses were investigated in both sham-operated rats and in rats with a unilateral electrolytic lesion of the magnocellular forebrain nuclei (MFN). A statistically significant ChAT decrease in cortical areas ipsilateral to the lesion was found in saline-treated lesioned rats. In the lesioned GMl-treated rats, ChAT activity was only reduced in the frontoparietal areas and was significantly increased in the ipsilateral parietooccipital areas as well as in both contralateral regions. NA levels in the cortex were neither significantly affected by the lesion nor by GM 1 treatment. The lesion impaired the acquisition of active and passive conditioned avoidance responses. GM1 treatment improved acquisition of the active avoidance response in the lesioned rats as indicated by a larger number of avoidances and a smaller number of escape failures during training in comparison with saline treatment. Ganglioside had no effect on the passive avoidance responses. These results demonstrate that GM 1 administration facilitates the recovery of the cortical cholinergic system and of behavioral responses impaired by an electrolytic lesion of the cholinergic forebrain nuclei.
Behavioural Pharmacology, 1995
Pharmacological Research, 1990
Naunyn Schmiedeberg S Archives of Pharmacology, 1990
Annali dell'Istituto superiore di sanità, 1988
General Pharmacology: The Vascular System, 1996
Adenosine is an endogenous neuromodulator that exerts its depressant effect on neurons by acting ... more Adenosine is an endogenous neuromodulator that exerts its depressant effect on neurons by acting on the A, adenosine receptor subtype. Excitatory actions of adenosine, mediated by the activation of the Az adenosine receptor subtype, have also been shown in the central nervous system. 2. Adenosine Az, receptors are highly localized in the striatum, as demonstrated by the binding assay of the Aza selective agonist, CGS2680, and by analysis of the A2 receptor mRNA localization with in situ hybridization histochemistry. However, adenosine Az, receptors, albeit at lower levels, are also localized in other brain regions, such as the cortex and the hippocampus. 3. In the striatum, adenosine A2, receptors are implicated in the control of motor activity. Evidences exists of an antagonistic interaction between adenosine A2, and dopamine Dz receptors. 4. Utilizing selective agonists and antagonists for adenosine Az, receptors, their role in the modulation of the release of several neurotransmitters (acetylcholine, dopamine, glutamate, GABA) has been extensively studied in the brain (striatum, cortex, hippocampus). Controversial results have been obtained and, because the overall effect of endogenous adenosine in the brain is that of an inhibitory tonus, the physiological meaning of the excitatory A2 receptor remains to be clarified. GEN PHARMAC 27;6:925-933, 1996 KEY WORDS. Adenosine, central nervous system, S. Latini et al. (2-CADO)>N-ethylcarboxamidoadenosine (NECA) > S-PIA > 2-(phenylamino)adenosine (CV1808), and for the A2 receptor is: 2-[[2-[4-(2-carboxyethyl)phenyl]ethyl]amino]-N-ethylcarboxamidoadenosine (CGS21680) =NECA> 2-CADO>CV 1808 =R-PIA> CPA=CHA>S-PIA (Williams, 1990). Recently, new adenosine agonists, such as 2-chloro-N6-cyclopentyladenosine (CCPA), with high affinity (Ki=0.4 nM) and selectivity (about 10,000-fold) for A~ receptors (Lohse et al., 1988b), and 2-hexynyl-NECA with high affinity (/(,=3.8 nM) and selectivity for A2 vs AI receptors, on the order of 12-fold, have been described (Cristalli et al., 1992). Both classes of adenosine receptors can be antagonized by xanthine compounds, such as caffeine, theophylline and related 8-phenylxanthines. More recently, a number of selective xanthine antagonists, such as 8-cyclopenthyl-l,3-dipropylxanthine (DPCPX) for A~ receptors (Ki=0.5 nM; AdAl =700) (Bruns etal., 1987b; Lohse et al., 1987), (E)-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-methylxanthine (KF17837) (K,=I.0 nM; AI/A2=62) (Nonaka et al., 1994), and 8-(3-chlorostyryl)caffeine (CSC) (K=54 nM; AI/A:=518) (Jacobson et al., 1993) for A2 receptors, have been developed. Several non-xanthine antagonists selective for A2 receptors, but with low water solubility, such as 4-amino-8-chloro-1-phenyl[1,2,4]triazolo[4,3-e~]quinoxaline (CP66713) (K, = 12 nM; AI/A2 = 13.0) (Sarges eta/., 1990), and 9-chloro-2-(2-furanyl)-5,6-dihydro-1,2,4-triazolo[1,5-c]quinazoline-5-imine (CGS15943A) (K=4 nM; At/A2=6) (Jarvis et al., 1991), have also recently been described. These compounds are useful in the characterization of A~ and A2 receptor subtypes. A sub-classification of the A~ receptor into A~.~, with high affinity for agonists and located in the central nervous system, and A~b, with low affinity and located in the peripheral nervous system, has been proposed (Gustafsson et al., 1990). However, there is currently no evidence at the molecular level to support the existence of A~, and A,~ receptors. A~ receptors have also been subclassified into A2,, a high-affinity receptor highly localized in the striatum, and A21~, a low-affinity receptor that exists in ahnost all areas of the brain (Bruns et al., 1986). Compounds such as CV1808 and CGS21680 have been developed that show high affinity for the rat striatal A,,, receptor (Bruns et al., 1986; Jarvis et al., 1989b), and could be used to differentiate A:, from either A> or A~ receptors. Adenosine A2~, and A2b receptors have also been cloned from several animal species (Linden et al., 1994). Recently, another adenosine receptor, termed A~, has been cloned in the rat brain (Zhou et al., 1992). Although this name was previously used by Ribeiro and Sebastiao (1986) to indicate a presynaptic adenosine receptor at the neuromuscular junction of the frog sartorius muscle, there seems to be no relationship between this and the cloned receptor. An adenosine receptor, termed A4, has been characterized in rat brain tissue using CV1808 (Cornfield et al., 1992), but it has not yet been cloned. Thus, the original AI and A., receptor classification has been extended, because to date 4 distinct adenosine receptors (AI, A~,~,, A2b, A~) have been cloned from a variety of mammalian species (see Table 1). LOCALIZATION OF ADENOSINE Az RECEPTORS IN THE BRAIN The distribution of adenosine receptor subtypes in the mammalian brain has been extensively studied (Goodman and Snyder, 1982; Jarvis, 1988). Adenosine A1 receptors have been well characterized by using binding assays (
Neurobiology of Acetylcholine, 1987
Histochemical and neurochemical investigations demonstrate that the mammalian cerebral cortex con... more Histochemical and neurochemical investigations demonstrate that the mammalian cerebral cortex contains a diffuse cholinergic network formed prevalently by nerve endings whose somata are located in the basal forebrain nuclei (Mesulam et al., 1983; Wainer et al., 1984). Minor contributions to the cortical cholinergic network are due to a direct projection from the large choline acetyltransferase (ChAT) immunoreactive cells in the pontomesencephalon (Mesulam et al., 1983) and, in the rat, by interneurons scattered throughout all cellular layers in all cortices which contain approximately 30% of total ChAT (Levey et al., 1984; McGeer et al., 1984).
Pharmacological Research, 1990