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M Hamon

Publications and source records attributed to M Hamon.

At least 145 records · Page 8Linked to original sources
PubMed1998

Novel potent and selective central 5-HT3 receptor ligands provided with different intrinsic efficacy. 1. Mapping the central 5-HT3 receptor binding site by arylpiperazine derivatives.

Synthesis and pharmacological evaluation of a series of condensed quinoline and pyridine derivatives bearing a N-methylpiperazine moiety attached to the 2-position of the quinoline or pyridine nucleus are described. 5-HT receptor binding studies revealed subnanomolar affinity for the 5-HT3 receptor subtype in some of the compounds under study. The most active compound (5b) displayed a Ki value about 1 order of magnitude higher than that of quipazine along with a higher selectivity. The potential 5-HT3 agonist/antagonist activity of four selected compounds was assessed in vitro on 5-HT3 receptor-dependent [14C]guanidinium uptake in NG 108-15 cells. Compound 5j acted as a 5-HT3 agonist in this assay with an EC50 value close to that reported for quipazine, while 5b was a partial agonist with an EC50 value of about 0.25 nM, and compound 5c possessed antagonist properties with an IC50 value (approximately 8 nM) in the same range as those of previously characterized 5-HT3 receptor antagonists. Qualitative and quantitative structure-affinity relationship studies carried out by making use of theoretical molecular descriptors allowed to elucidate the role of the main pharmacophoric components and to develop a model for the interaction of the 5-HT3 ligands related to quipazine with their receptor.

Animals↗
PubMed1998

c-Fos induction in the rostroventrolateral medulla by 5-HT3 receptor activation in the nucleus tractus solitarius.

The nucleus tractus solitarius (NTS) plays a crucial role in the reflex control of sympathetic tone through direct projections to the caudal and rostral regions of the ventrolateral medulla (CVLM and RVLM respectively). 5-HT3 receptor stimulation in the NTS increases both blood pressure and sympathetic tone. In order to investigate whether the ventrolateral medulla participates in these effects, the expression of c-Fos protein, a marker of neuronal activation, was examined at this level after intra-NTS microinjections of 1-(m-chlorophenyl)-biguanide, a selective 5-HT3 receptor agonist. A marked increase (93%) in the density of c-Fos-immunoreactive neurons was restricted to the most rostral part of the RVLM after this treatment. This effect could be prevented by prior intra-NTS microinjection of ondansetron, a selective 5-HT3 antagonist. These results suggest the participation of sympathoexcitatory neurons in the rostral RVLM in the pressor response to 5-HT3 receptor stimulation in the NTS.

Analysis of Variance↗
PubMed1998

Dual determination of angiotensin-converting enzyme and angiotensin-II type 1 receptor genotypes as predictors of restenosis after coronary angioplasty.

This study sought to assess the potential influence of the angiotensin-converting enzyme (ACE) and angiotensin II type 1 (AT1) receptor gene polymorphisms on restenosis after coronary balloon angioplasty. The authors conclude that screening for genetic suspectibility to restenosis based on genotyping of ACE and AT1 receptor polymorphisms before conventional balloon angioplasty is not clinically useful.

Angioplasty, Balloon, Coronary↗
PubMed1998

Assessment of pyrin gene mutations in Turks with familial Mediterranean fever (FMF).

Familial Mediterranean fever (FMF) is an autosomal recessive disease clinically characterized by recurrent short self-limited attacks of fever accompanied by peritonitis, pleurisy, and arthritis and can lead to amyloidosis and renal failure in the longer term. It is prevalent mainly in non-Ashkenazi Jews, Armenians, Turks, and Arabs. Due to the lack of an accurate diagnostic test, patients often experience years of attacks and invasive diagnostic procedures before the correct diagnosis is made and adequate treatment is begun. Recently, the gene responsible for FMF, denoted pyrin, has been cloned, and three disease mutations have been described (French FMF Consortium, 1997; International FMF Consortium, 1997). In the current study we assessed the spectrum of mutations in this gene in 16 unrelated families of Turkish origin. The three previously reported missense mutations (Met-Ile at codon 680, Met-Val at codon 694, and Val-Ala at codon 726) accounted for 29 of the 34 disease alleles. In one patient in whom no disease mutation was identified, the clinical picture was atypical enough to raise questions regarding the diagnosis. These results imply that the origin of FMF in Turkey is heterogeneous, that molecular diagnosis of FMF is possible in the majority of cases and clinically helpful, and that delineation of the undiscovered disease mutation(s) in the remaining cases remains a high priority.

Armenia↗
PubMed1998

Immunolabelling of the rat intestinal tract with antibodies specific to the long form of the 5-hydroxytryptamine3 receptor.

The mouse 5-hydroxytryptamine3 (5-HT3) type of serotonin receptors is expressed as two forms, 5-HT3R-A(L) and 5-HT3R-A(S), generated by alternative splicing of its primary transcript, that differ by a stretch of six amino acids in the second intracellular loop domain. Because this six-amino acid region contains a putative phosphorylation site that may be important for the function and/or regulation of 5HT3R-A(L) receptor, specifically, we developed polyclonal antibodies as appropriate tools for studies relevant to this question. Antibodies against a 20-amino acid peptide corresponding to the sequence of 5-HT3R-A(L) at the level of this six-amino acid region were obtained as soon as one month after injection of this synthetic peptide to rabbits. Immunocytochemistry with these antibodies led to a strong positive labelling of plasma membrane, reticulum and Golgi apparatus of COS-7 cells expressing cloned murine 5-HT3R-A(L), whereas COS-7 cells expressing similar levels of 5-HT3R-A(S) exhibited only a very weak labelling. Immunoblots of fusion proteins combining glutathion-S-transferase and the second cytoplasmic loop of 5-HT3R-A(L) or 5-HT3R-A(S) revealed a c. 20-fold selectivity of the antibodies for the first, long form, as evaluated by densitometric analysis of enhanced chemiluminescence detection. Similarly, immunoblots of COS-7 cells transfected with cloned 5-HT3 receptors showed that the anti-peptide antibodies detected a band at 53,000 mol. wt only in cells transfected with 5-HT3R-A(L). Under optimal conditions, antibodies immunoprecipitated 52% of 5-HT3R-A(L), but only 11% of 5-HT3R-A(S), solubilized from COS-7 cells transfected with the respective encoding plasmids. In the rat, no immunoautoradiographic labelling by the anti-peptide antibodies could be detected in brain structures which had previously been described to express preferentially a short form of the 5-HT3 receptor. In contrast, a strong immunolabelling was found in the intestinal mucosa, especially in the rat fetus (at the 17th embryonic day), suggesting the possible participation of the 5-HT3R-A(L) isoform in the development of this tissue. These results show that specific antibodies are useful tools for the visualization of the least abundant 5-HT3 receptor isoform in rat tissue.

Alternative Splicing↗
PubMed1998

Endothelial expression of the 5-hydroxytryptamine1B antimigraine drug receptor in rat and human brain microvessels.

In addition to triggering vasoconstriction of peripheral blood vessels, which led to its discovery as a circulating neurohormone 50 years ago, serotonin (5-hydroxytryptamine) acts as a neurotransmitter/ modulator in the central nervous system and regulates local cerebral blood flow and vascular permeability through direct and indirect effects on intraparenchymal microvessels. Among the various 5-hydroxytryptamine receptors which mediate these effects, particular attention has been paid to the 5-hydroxytryptamine1B and 5-hydroxytryptamine1D subtypes, as the preferred targets of modern antimigraine agents. Immunoelectron microscopic labeling of the 5-hydroxytryptamine1B receptor in rat brain parenchyma has revealed a distinct localization to the endothelium of microvessels, which was predominantly cytoplasmic as opposed to membrane-bound, contrary to that on preterminal unmyelinated axons [Riad et al. (1997) Soc. Neurosci. Abstr. 23, 1214]. Similar observations have now been made in human cortical tissue, in which the expected localization of the vascular 5-hydroxytryptamine1B receptor to periarteriolar myocytes was also confirmed. Such a dual localization in human brain microvessels suggests that the 5-hydroxytryptamine1B receptor might mediate opposite effects, vasodilatory and contractile, depending upon its activation by circulating or centrally released 5-hydroxytryptamine. It raises new possibilities as regards 5-hydroxytryptamine effects on human brain microvessels in health and disease, and notably the triggering of migraine headache.

Animals↗
PubMed1998

Antagonist properties of (-)-pindolol and WAY 100635 at somatodendritic and postsynaptic 5-HT1A receptors in the rat brain.

1. The aim of the present work was to characterize the 5-hydroxytryptamine1A (5-HT1A) antagonistic actions of (-)-pindolol and WAY 100635 (N-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-N-(2-pyridinyl) cyclohexane carboxamide). Studies were performed on 5-HT1A receptors located on 5-hydroxytryptaminergic neurones in the dorsal raphe nucleus (DRN) and on pyramidal cells in the CA1 and CA3 regions of the hippocampus in rat brain slices. 2. Intracellular electrophysiological recording of CA1 pyramidal cells and 5-hydroxytryptaminergic DRN neurones showed that the 5-HT1A receptor agonist 5-carboxamidotryptamine (5-CT) evoked in both cell types a concentration-dependent cell membrane hyperpolarization and a decrease in cell input resistance. On its own, (-)-pindolol did not modify the cell membrane potential and resistance at concentrations up to 10 microM, but it antagonized the 5-CT effects in a concentration-dependent manner. Similar antagonism of 5-CT effects was observed in the CA3 hippocampal region. (-)-Pindolol also prevented the 5-HT1A receptor-mediated hyperpolarization of CA1 pyramidal cells due to 5-HT (15 microM). In contrast, the 5-HT-induced depolarization mediated by presumed 5-HT4 receptors persisted in the presence of 3 microM (-)-pindolol. 3. In the hippocampus, (-)-pindolol completely prevented the hyperpolarization of CA1 pyramidal cells by 100 nM 5-CT (IC50=92 nM; apparent KB=20.1 nM), and of CA3 neurones by 300 nM 5-CT (IC50=522 nM; apparent KB= 115.1 nM). The block by (-)-pindolol was surmounted by increasing the concentration of 5-CT, indicating a reversible and competitive antagonistic action. 4. Extracellular recording of the firing rate of 5-hydroxytryptaminergic neurones in the DRN showed that (-)-pindolol blocked, in a concentration-dependent manner, the decrease in firing elicited by 100 nM 5-CT (IC50=598 nM; apparent KB= 131.7 nM) or 100 nM ipsapirone (IC50= 132.5 nM; apparent KB= 124.9 nM). The effect of (-)-pindolol was surmountable by increasing the concentration of the agonist. Intracellular recording experiments showed that 10 microM (-)-pindolol were required to antagonize completely the hyperpolarizing effect of 100 nM 5-CT. 5. In vivo labelling of brain 5-HT1A receptors by i.v. administration of [3H]-WAY 100635 ([O-methyl-3H]-N-(2-(4-(2-methoxyphenyl)-1 -piperazinyl)ethyl-N-(2-pyridyl)cyclo-hexane-carboxamide) was used to assess their occupancy following in vivo treatment with (-)-pindolol. (-)-Pindolol (15 mg kg[-1]) injected i.p. either subchronically (2 day-treatment before i.v. injection of [3H]-WAY 100635) or acutely (20 min before i.v. injection of [3H]-WAY 100635) markedly reduced [3H]-WAY 100635 accumulation in all 5-HT1A receptor-containing brain areas. In particular, no differences were observed in the capacity of (-)-pindolol to prevent [3H]-WAY 100635 accumulation in the DRN and the CAI and CA3 hippocampal areas. 6. Intracellular electrophysiological recording of 5-hydroxytryptaminergic DRN neurones showed that WAY 100635 prevented the hyperpolarizing effect of 100 nM 5-CT in a concentration-dependent manner (IC50=4.9 nM, apparent KB=0.25 nM). In CA1 pyramidal cells, hyperpolarization induced by 50 nM 5-CT was also antagonized by WAY 100635 (IC50 = 0.80 nM, apparent KB= 0.28 nM).

Animals↗
PubMed1998

Up- and down-expression of the dopamine transporter by plasmid DNA transfer in the rat brain.

The functional role of the dopamine transporter (DAT) in central dopaminergic neurotransmission was assessed further by investigating the consequences on dopamine (DA) turn-over of up- and down-regulation of this protein induced by a non-viral gene transfer approach. For this purpose, expression plasmids containing the sense or antisense coding sequence of DAT complexed with the cationic polymer, polyethylenimine (PEI), were injected into the rat substantia nigra, the brain region containing the majority of DA cell bodies. Before in vivo injection, the efficacies of the different DNA constructs were assessed by transfection studies into LLC-PK1 cells. Stereotaxic administration of the sense plasmid complexed to PEI induced, 3 days later, a significant increase in the immunoautoradiographic labelling by anti-DAT antibodies of the substantia nigra and various DA projection areas. These effects were associated with a significantly enhanced capacity of striatal synaptosomes to take up [3H]-DA and lasted up to 14 days postinjection. In contrast, 7 days after intranigral administration of the antisense plasmid complexed to PEI, we observed a significant decrease of DAT immunolabelling in the substantia nigra and [3H]-DA uptake by striatal synaptosomes. Whereas DA turnover in the striatum was unaltered 3 days after intranigral administration of the sense plasmid, it was increased 7 days after intranigral administration of the antisense construct. These data indicate that non-viral transfer of the sense or antisense coding sequence of DAT can be used as a novel approach to induce long-term changes in central DA neurotransmission.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1998

Herpes simplex virus 1-mediated transfer of preproenkephalin A in rat dorsal root ganglia.

Recombinant herpes simplex virus-1 encoding the rat preproenkephalin A (HSVLatEnk1) was generated for driving the expression of preproenkephalin A-derived peptides in dorsal root ganglia of rats in vivo. Three weeks after infection via the hind footpads, quantitative RT-PCR and in situ hybridization experiments showed a strong expression of preproenkephalin A mRNA in lumbar dorsal root ganglia. In addition, a 40-160% increase in radioimmunoassayable Met-enkephalin-like material concentrations was found in the dorsal spinal cord and dorsal root ganglia, respectively, at the lumbar level in HSVLatEnk1-infected rats as compared with animals infected with beta-galactosidase-encoding recombinant herpes simplex virus-1 or control rats. These data demonstrate the efficacy of the preproenkephalin A encoding vector and suggest that it should help in elucidating the role of Met-enkephalin-containing primary afferent fibers in pain transmission and/or control.

Animals↗
PubMed1998

Differential membrane targeting and pharmacological characterization of chimeras of rat serotonin 5-HT1A and 5-HT1B receptors expressed in epithelial LLC-PK1 cells.

The serotonin 5-HT1A and 5-HT1B receptors are two structurally related but pharmacologically distinguishable 5-HT receptor types. In brain, the 5-HT1A receptor is localized on the soma and dendrites of neurons, whereas the 5-HT1B receptor is targeted to the axon terminals. We previously showed that these two receptors are targeted in different membrane compartments when stably expressed in the epithelial LLC-PK1 cell line. Further investigations on the mechanisms responsible for their differential targeting were done by constructing chimeras of 5-HT1A and 5-HT1B receptors still able to bind specifically [3H]lysergic acid diethylamide and selective agonists and antagonists. Their cellular localization examined by confocal microscopy suggests that the third intracellular domain of the 5-HT1B receptor was responsible for its Golgi-like localization in transfected LLC-PK1 cells. In contrast, the third intracellular domain of the 5-HT1A receptor apparently allowed the sorting of the chimeras to the plasma membrane. Further inclusion of the C-terminal domain of the 5-HT1A receptor in their sequence led to a basolateral localization, whereas that of the 5-HT1B receptor allowed an apical targeting, suggesting the existence of a targeting signal in this portion of the receptor(s).

Amino Acid Sequence↗
PubMed1998

Lipomatous differentiation in ependymomas: a report of three cases and comparison with similar changes reported in other central nervous system neoplasms of neuroectodermal origin.

Three cases of surgically removed ependymomas with lipomatous transformation of tumor cells are reported. Patients' ages were 13, 16, and 48 years at the time of operation. One patient's tumor was located in the third ventricle; the other two occupied paraventricular hemispheric white matter. Histologically all three cases fulfilled the criteria of ependymomas. In case 1, electron microscopy also confirmed this diagnosis, and preoperative radiologic studies (scans) suggested large amounts of lipids to be present in the tumor. Histologically, in all three cases many tumor cells contained fat droplets coalescing into a single large droplet, resulting in an appearance indistinguishable from adipocytes by conventional stains, but maintaining immunohistological positivity for glial fibrillary acidic protein and neuron-specific enolase in the cytoplasmic rims of the affected cells, attesting to their glial nature as opposed to being true adipocytes in a mixed glial/mesenchymal hamartoma. The alterations were also different from the "xanthomatous" changes seen in some gliomas. Lipomatous transformation of neuroectodermal tumor cells has been previously observed in neurocytomas, medulloblastomas, cerebellar and spinal cord astrocytomas, and primitive neuroectodermal tumors. Our three cases represent the first reported ependymomas with such changes. In medulloblastomas of adults, lipomatous changes have been found to signal relatively benign biologic behavior. So far, all three of our patients are doing well, but only more extended follow-up will show whether such benign behavior applies to lipomatous ependymomas as well.

Adolescent↗
PubMed1998

Intramural injection of biodegradable microspheres as a local drug-delivery system to inhibit neointimal thickening in a rabbit model of balloon angioplasty.

Restenosis remains the major limitation of coronary angioplasty. The objective of this study was to develop microspheres able to be delivered at the angioplasty site for long-term drug release and to test their effects in a model of balloon angioplasty. Polylactic-co-glycolide acid microspheres (5-10 microm in diameter) were prepared by using an oil-in-water emulsion-solvent evaporation method. In vitro experiments with hydrocortisone-loaded microspheres revealed a hydrocortisone release for 4 weeks. We studied the in vivo effect of injection of microspheres into the arterial wall of New Zealand White rabbits by using a perforated balloon. Deep penetration of microspheres in the arterial wall was documented immediately after angioplasty. Intimal hyperplasia was assessed in iliac arteries 4 weeks after angioplasty. The morphometric analysis was performed in four groups of animals; the first group was subjected only to conventional angioplasty (control, n = 10), whereas the other three groups after conventional angioplasty were received perforated balloon angioplasty with saline (n = 10), microspheres (n = 10), or hydrocortisone-loaded microspheres (n = 7). Intramural injection of saline did not induce greater intimal hyperplasia compared with control (0.17 +/- 0.03 vs. 0.18 +/- 0.03 mm2, respectively). Microspheres injection was associated with a trend toward a greater degree of intimal hyperplasia that did not reach statistical significance. Hydrocortisone-loaded microspheres were associated with a significant reduction in intimal hyperplasia compared with unloaded microspheres (0.16 +/- 0.02 vs. 0.26 +/- 0.03 mm2, respectively). The polylactic-co-glycolide acid microspheres are well tolerated, easily injected into the arterial wall, and the increase of intimal hyperplasia is easily inhibited by release of hydrocortisone for 4 weeks after initial injury.

Angioplasty, Balloon↗
PubMed1998

Construction of an approximately 700-kb transcript map around the familial Mediterranean fever locus on human chromosome 16p13.3.

We used a combination of cDNA selection, exon amplification, and computational prediction from genomic sequence to isolate transcribed sequences from genomic DNA surrounding the familial Mediterranean fever (FMF) locus. Eighty-seven kb of genomic DNA around D16S3370, a marker showing a high degree of linkage disequilibrium with FMF, was sequenced to completion, and the sequence annotated. A transcript map reflecting the minimal number of genes encoded within the approximately 700 kb of genomic DNA surrounding the FMF locus was assembled. This map consists of 27 genes with discreet messages detectable on Northerns, in addition to three olfactory-receptor genes, a cluster of 18 tRNA genes, and two putative transcriptional units that have typical intron-exon splice junctions yet do not detect messages on Northerns. Four of the transcripts are identical to genes described previously, seven have been independently identified by the French FMF Consortium, and the others are novel. Six related zinc-finger genes, a cluster of tRNAs, and three olfactory receptors account for the majority of transcribed sequences isolated from a 315-kb FMF central region (between D16S468/D16S3070 and cosmid 377A12). Interspersed among them are several genes that may be important in inflammation. This transcript map not only has permitted the identification of the FMF gene (MEFV), but also has provided us an opportunity to probe the structural and functional features of this region of chromosome 16.

Amino Acid Sequence↗
PubMed1998

Pharmacological approaches to the prevention of restenosis after coronary angioplasty.

Restenosis in the months following a successful percutaneous transluminal coronary angioplasty (PTCA) remains the main limitation to this technique for myocardial revascularisation. Despite intensive investigation in this area, no pharmacological therapy has yet been found to be useful in preventing restenosis after conventional balloon angioplasty. The occurrence of restenosis, which is now known to be caused by both vessel remodelling and neointimal hyperplasia, might be reduced in the future by a combined mechanical and pharmacological approach. Although systemic administration of 'antirestenosis' drugs has not yet been tested to prevent restenosis after coronary stenting, it is very likely that pharmacological inhibition of neointimal hyperplasia within coronary stents will take advantage of local delivery techniques. In addition to local drug delivery catheters that are available, the stent itself may be coated with polymers and serve as a platform for drug delivery. The continued attractiveness of PTCA, as an alternative to medical treatment or bypass surgery for patients with coronary artery disease, will depend upon our ability to control the restenotic process.

Angioplasty, Balloon, Coronary↗
PubMed1998

[Interactions between central opioidergic and cholecystokininergic systems in rats: possible significance for the development of of opioid tolerance].

Numerous data suggest that cholecystokinin (CCK) acts as an opioid-modulating peptide. Because pharmacological and behavioural studies have shown that CCK reduces the analgesic effects of opioids, an opioid-mediated activation of CCK-containing neurones has been proposed to be responsible for the development of opioid tolerance. In an attempt to directly assess this hypothesis, we have examined, in naive or morphine-tolerant/dependent rats, the possible influence of opioid-receptor ligands on--1 the release of CCK from spinal cord slices and--2 the extracellular levels of CCK in the frontal cortex in awake, freely moving animals. Whereas the stimulation of mu or delta 1 receptors inhibited the release of the peptide, the stimulation of delta 2 receptors increased CCK release. Morphine also increased CCK release, via an action at delta 2 receptors. The blockade of delta 1 receptors resulted in an enhancement of the peptide release, suggesting that endogenous opioids probably exert inhibitory tonic influence on CCK release through the stimulation of delta 1 receptors. In rats rendered tolerant/dependent, the inhibitory effects of opioids on CCK release, due to the stimulation of mu or delta 1 receptors, and the enhancing effect of delta 1 receptor blockade, were no longer present. In contrast, the delta 2-mediated increase in CCK release persisted. Thus, in morphine-tolerant/dependent rats, opioids apparently retain only their excitatory effects on CCK-containing neurones. These data support the idea that morphine exerts an excitatory influence on central CCKergic neurones, which could tend to reduce the analgesic action of the alkaloid, and are in line with the hypothesis that morphine tolerance/dependence is associated with an activation of CCK-containing neurones.

Analgesics, Opioid↗
PubMed1998

[Current status of post-infarction cardiogenic shock and revascularization].

Despite improved management of myocardial infarction, the incidence of cardiogenic shock remains constant at about 7.5% of cases. Patients who develop cardiogenic shock are older and much more often women. The site of infarction is usually anterior, transmural with greater left ventricular systolic dysfunction and a higher increase in cardiac enzymes. Diastolic intra-aortic balloon pumping is the usual treatment but survival only seems to be increased in patients undergoing revascularisation. Surgical revascularisation and circulatory assist devices have been proposed but patient selection in these studies was biased and optimised the results. The effect of thrombolysis was analysed in a subgroup of patients in the GISSI study. The 30 day mortality was 69.9% in 146 patients treated by streptokinase and 70.1% in patients given placebo. Thrombolysis only benefitted patients with an anterior myocardial infarction aged less than 65 and treated within 6 hours of the onset of pain. Although there are no randomised studies of the value of angioplasty in patients in cardiogenic shock. Several uncontrolled series suggest that this type of procedure reduces short and long-term mortality. However, the prognosis is not as good when unselected consecutive groups of patients are studied in whom infarction is complicated by cardiogenic shock immediately and who undergo "aggressive" revascularisation: 72% of patients die in hospital and there are few long-term survivors. The prognosis appears to be particularly poor in patients over 70 years of age with a previous history of myocardial infarction or who undergo prolonged pre-hospital cardiopulmonary resuscitation. However, the implantation of coronary stents associated with circulatory assist devices seems to improve the prognosis of infarction complicated by cardiogenic shock by ensuring adequate coronary flow and reducing the risk of reocclusion.

Adult↗
PubMed1997

Cloning of a functional vesicular GABA and glycine transporter by screening of genome databases.

The unc-47 locus of Caenorhabditis elegans has been suggested to encode a synaptic vesicle GABA transporter. Here we used hydropathy plot analysis to identify a candidate vesicular GABA transporter in genomic sequences derived from a region of the physical map comprising unc-47. A mouse homologue was identified and cloned from EST database information. In situ hybridization in rat brain revealed codistribution with both GABAergic and glycinergic neuronal markers. Moreover, expression in COS-7 and PC12 cells induced an intracellular, glycine-sensitive GABA uptake activity. These observations, consistent with previous data on GABA and glycine uptake by synaptic vesicles, demonstrate that the mouse clone encodes a vesicular inhibitory amino acid transporter.

Amino Acid Sequence↗