Interaction of CDP-choline with synaptosomal transport of biogenic amines and their precursors in vitro and in vivo in the rat corpus striatum (original) (raw)
European Journal of Pharmacology, 1984
E. RICHELSON and M. PFENNING, Blockade by antidepressants and related compounds of biogenic amine uptake into rat brain synaptosomes: most antidepressants selectively block norepinephrine uptake, European J. Pharmacol. 104 (1984) 277-286. Inhibitor constants (Ki's) for blocking uptake of [3H]norepinephrine, [3H]serotonin, and [3H]dopamine into synaptosomal preparations of rat brain were determined for 25 antidepressants and putative antidepressants, some neuroleptics, stimulants, antihistamines and other monoamines. With Ki's we could directly and definitively compare the relative potencies of a drug at the three processes. Eighteen or 72% of the antidepressants (including tertiary amine tricyclics) were more potent at blocking uptake of norepinephrine than at blocking uptake of serotonin. Considering all three biogenic amines, 17 antidepressants were selective for blocking [3H]norepinephrine uptake, one (bupropion) was selective although weak for blocking [3H]dopamine uptake, and the remainder were selective for blocking [3H]serotonin uptake. The neuroleptics chlorpromazine and promazine were relatively potent at blocking uptake of [3H]norepinephrine and some tricyclic antidepressants (notably, trimipramine and butriptyline) were very weak at blocking any biogenic amine uptake.
Journal of Pharmacology and Experimental Therapeutics, 2005
Previous studies identified partial inhibitors of serotonin (5-HT) transporter and dopamine transporter binding. We report here on a partial inhibitor of 5-HT transporter (SERT) binding identified among a group of 1-[2-[bis(4-fluorophenyl)methoxy]ethyl]-4-(3-phenylpropyl)piperazine analogs (4-[2-[bis(4-fluorophenyl)methoxy]ethyl]-1-(2-trifluoromethyl-benzyl)-piperidine; TB-1-099). Membranes were prepared from rat brains or human embryonic kidney cells expressing the cloned human dopamine (hDAT), serotonin (hSERT), and norepinephrine (hNET) transporters. -(4Ј-125 Iodophenyl)tropan-2-carboxylic acid methyl ester ([ 125 I]RTI-55) binding and other assays followed published procedures. Using rat brain membranes, TB-1-099 weakly inhibited DAT binding (K i ϭ 439 nM), was inactive at NET binding ([ 3 H]nisoxetine), and partially inhibited SERT binding with an extrapolated plateau ("A" value) of 20%. Similarly, TB-1-099 partially inhibited [ 125 I]RTI-55 binding to hSERT with an extrapolated plateau (A value) of 14%. Upon examining the effect of increasing concentrations of TB-1-099 on the apparent K d and B max of [ 125 I]RTI-55 binding to hSERT, we found that TB-1-099 decreased the B max in a dose-dependent manner and affected the apparent K d in a manner well described by a sigmoid dose-response curve. TB-1-099 increased the K d but not to the magnitude expected for a competitive inhibitor. In rat brain synaptosomes, TB-1-099 noncompetitively inhibited [ 3 H]5-HT, but not [ 3 H]dopamine, uptake. Dissociation experiments indicated that TB-1-099 promoted the rapid dissociation of a small component of [ 125 I]RTI-55 binding to hSERT. Association experiments demonstrated that TB-1-099 slowed [ 125 I]RTI-55 binding to hSERT in a manner unlike that of the competitive inhibitor indatraline. Viewed collectively, these results support the hypothesis that TB-1-099 allosterically modulates hSERT binding and function. The serotonin (5-HT) transporter (SERT) is a member of the twelve transmembrane-spanning transporter family that transports 5-HT across cell membranes in a sodium-dependent manner (Amara and Kuhar, 1993; Uhl and Johnson, 1994). SERT, in the central nervous system, is an important target for a wide range of medications used to treat a variety of psychiatric conditions such as anxiety, depression, and obsessive-compulsive disorder (Gorman and Kent, 1999; Zohar and Westenberg, 2000). Drugs that interact with transporters generally interact with this protein in two distinct ways. Reuptake inhibitors bind to transporter proteins but are not transported. These drugs elevate extracellular concentrations of transmitter by blocking transporter-mediated uptake of transmitters from the synapse. Substrate-type releasers bind to transporter proteins and are subsequently transported into the cytoplasm of nerve terminals. Releasers elevate extracellular Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
Choline: High Affinity Uptake in Vivo by Rat Hippocampus
Journal of Neurochemistry, 1977
HICholine uptake has been measured in riro in the rat hippocampus. Pharmacological agents and lesions which profoundly affect sodium-dependent, high-affinity ['Hlcholine uptake in c i w similarly affect ['Hlcholine uptake measured in r i m. Pentobarbital (65 mgikg) and oxotremorine (0.75 mg'kg) cause a decrease in ['H]choline uptake. Scopolamine (5 mg/kg) and iontophoretically applied extracellular potassium cause an increase in ['Hlcholine uptake. Septa1 lesions cause a decrease in ['Hlcholine uptake. Application of the general method may allow direct examination of presynaptic function and neural integration in the undisrupted living mammalian brain.
Neuroscience, 2006
Behavioral and neuronal abnormalities observed in mice exhibiting a reduced expression of the dopamine transporter model important aspects of schizophrenia, addiction, and attentional disorders. As the consequences of a chronic hyperdopaminergic tone for striatal output regulation have remained poorly understood, the present experiments were designed to determine the status of striatal interneuronal cholinergic neurotransmission in dopamine transporter knockdown animals. The high-affinity choline transporter represents the rate-limiting step of acetylcholine synthesis and release. Compared with wild type mice, striatal highaffinity choline transporter expression in dopamine transporter knockdown mice was significantly decreased. As in vivo basal striatal acetylcholine release did not differ between the strains, reduced high-affinity choline transporter expression in dopamine transporter knockdown mice was not due to reduced basal cholinergic activity. Furthermore, the proportion of high-affinity choline transporters expressed in plasma membrane-enriched versus vesicular membraneenriched fractions did not differ from wild type animals, suggesting that changes in intracellular high-affinity choline transporter trafficking were not associated with lower overall levels of striatal high-affinity choline transporters. Synaptosomal choline uptake assays indicated a reduced capacity of striatal high-affinity choline transporters in dopamine transporter knockdown mice, and thus the functional significance of the reduced level of high-affinity choline transporter expression. Likewise, in vivo measures of the capacity of striatal high-affinity choline transporters to clear increases in extracellular choline concentrations, using choline-sensitive microelectrodes, revealed a 37-41% reduction in hemicholinium-sensitive clearance of exogenous choline in dopamine transporter knockdown mice. Furthermore, clearance of potassium-evoked choline signals was reduced in dopamine transporter knockdown mice (1.63؎0.15 M/s) compared with wild type animals (2.29؎0.21 M/s). Dysregulated striatal cholinergic neurotransmission is hypothesized to disrupt the integration of thalamic and cortical information at spiny projection neurons and thus to contribute to abnormal stria-tal information processing in dopamine transporter knockdown mice.
The Japanese Journal of Pharmacology, 1991
The characteristics of [3H]choline transport with high affinity were investigated using primary cultured neurons obtained from the mouse cerebral cortex. [3H]Choline uptake was saturable as a function of extracellular [3H]choline concentration. Analysis by Lineweaver-Burk plot revealed that [3H]choline was transported into neurons by a high affinity transport system with a K,,, value of 19.8 ± 0.8,uM and Vmax value of 0.334 ± 0.022 nmol/mg protein/min. This high affinity transport of [3H]choline was significantly inhibited by the withdrawal of sodium from the incubation medium, incubation at low temperature (4°C) and addition of metabolic inhibitors such as monoiodoacetate. These results indicate that the high affinity [3H]choline uptake in primary cultured neurons is sodium-and energy-dependent. Hemicholinium-3 also showed a competitive inhibition on the [3H]choline transport. Depolarization by high K+ induced an enhancement of the [3H]choline uptake in the presence of Ca t+. The crude synaptosomal fraction obtained from primary cultured neurons possessed approximately forty-fold higher synthesizing activity of [3H]acetylcholine from [3H]choline than that found in the homogenate preparation of cultured neurons. The present results strongly suggest that the primary cultured neurons used in this study possess a sodium-and energy-dependent high-affinity choline uptake system as well as a synthesizing system for acetylcholine. Possible usefulness of these neurons for investigating neuronal uptake of choline and its functional role in the biosynthesis of acetylcholine are also suggested.
The Uptake and Subcellular Distribution of Aromatic Amines in the Brain of the Rat
Journal of Neurochemistry, 1971
The hydroxylated phenylethylamines ptyramine, m-tyramine, octopamine, metaraminol and norepinephrine were accumulated by homogenates of rat brain much more vigorously than j-phenethylamine or amphetamine. The affinity concentrations (Km) for initial (5-min) uptake by homogenates of whole brain were 0 5 , 3 and 6 /*M for DL-norepinephrine, p-tyramine and m-octopamine, respectively. The uptake of these three hydroxylated compounds was much more vigorous in striatal tissue than in cortical tissue, and in both tissues the rate of uptake decreased in the sequence: norepinephrine > tyramine > octopamine. The uptake of these three substances was inhibited by reduced temperature, by lack of glucose, by CNand DNP, and by desmethylimipramine, cocaine and ouabain. The uptake of norepinephrine and octopamine appeared to require Na+. Pretreatment of rats with reserpine or 6-hydroxydopamine decreased the ability of brain to take up norepinephrine or octopamine. Previously accumulated labelled phenylethylamines migrated in sucrose density gradients with a peak of radioactivity corresponding to an equilibrium position of catecholamine-containing nerve endings. The magnitude of the retention of ["lamine in this synaptosornal peak decreased in the order: norepinephrine > octopamine > tyramine. The accumulated amines were released by sonic, osmotic and thermal stresses which disrupt neuronal membranes. The presence of a 8-hydroxyl group appeared to protect amines from destruction by monoamine oxidase, presumably by virtue of uptake in presynaptic storage vesicles. During superfusion, tyramine and metaraminol appeared to displace [3H]norepinephrine from binding sites in brain slices. THE POSSIBILITY that aromatic amines may accumulate at nerve endings under certain conditions has been investigated in the peripheral sympathetic nervous system. When such compounds are taken up, stored in, and released by nerve stimulation from nerve terminals, but exert only weak post-synaptic effects, they have been designated 'false' neurochemical transmitters (CARLSSON and LINDQVIST, 1962; DAY and RAND, 1963; KOPIN, 1968). In the peripheral nervous system, the hydroxylation of phenyl-alkyl amines appears to correlate with their uptake and retention in sympathetic nerve endings (MUSACCHIO, KOPIN and WEISE, 1965; IVERSEN, 1967), and #Lhydroxylation of phenylethylamines is an important prerequisite for the release of the compounds upon sympathetic nerve stimulation (FISCHER, HORST and KOPIN, 1965). The actions of certain drugs have been attributed to the accumulation of such inactive transmitter substitutes. Thus, the hypotension and relief of angina pectoris which may follow the administration to patients of monoamine oxidase (MAO) inhibitors, and the treatment of hypertension with a-methyl-m-tyrosine or a-methyl-DOPA (precursors of the relatively inactive sympathomimetic amines, metaraminol and a-methyl-norepine-Supported by U.S.
The change with age in biogenic amines and their metabolites in the striatum of the rat
Archives of Gerontology and Geriatrics, 1986
The changes in the content of the biogenic amines and their metabolites in the striatum of the rat during the aging period (3-30 months) have been studied. The maximum levels of dopamine (DA) have been found at 6 months of age and this concentration is maintained until 24 months. Between 24 to 30 months there is a decrease in the concentration of this compound. At that time, there is a slight increase in 3,4-dihydroxyphenyl acetic acid (DOPAC) and homovanillic acid (HVA) concentration, the main metabolites of DA, which suggests a slight increase in DA metabolism. The 3-methoxytyramine (3-MT) concentration also increases at this time. The maximum concentration of noradrenaline (NA) was also found at 6 months of age. Tryptophan has the maximum concentration after DA and this is maintained over the life-span of the rat. The concentration of serotonin (5-HT) is high and does not change during this period. However, the concentration of 5-HT, as occurred with DA, decreased between 24 and 30 months. Also the DA/5-HT ratio does not change during the period studied. biogenic amines; dopamine, serotonin, noradrenaline, aging; brain monoamine contents during aging
Acta pharmacologica et toxicologica, 1985
Uptake and biotransformation of radioactive choline (3H-Ch) have been studied in P2 fractions from different brain regions of mice treated with different doses of sodium pentobarbital (45-120 mg/kg intraperitoneally) or saline. Sodium dependent uptake (SDU) has been measured as the difference between results of incubations with Na+ in the incubation medium and when the sodium salts were replaced by Trisphosphate and sucrose. The uptake of radioactivity increased during the incubation with 3H-Ch but the proportion of 3H-ACh was the same at all time points. The proportion of 3H-ACh to 3H-Ch in the P2 pellet was 86, 81 and 69 per cent in hippocampus, striatum and cortex, respectively. Omission of sodium ions in the incubation medium reduced uptake of 3H-Ch by about 90 per cent at 1 microM Ch in the incubation medium and the proportion of 3H-ACh to 3H-Ch was only 10 to 20 per cent while the proportion of 3H-PhCh increased from insignificant amounts to between 20 to 30 per cent. There we...