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Vale C, Vilaro MT, Rodriguez-Farre E, Sunol C: Effects of the conformationally restricted GABA analogues, cis- and trans-4-aminocrotonic acid, on GABA neurotransmission in primary neuronal cultures. J Neurosci Res. 1999 Jul 1;57(1):95-105.
The effects of the GABA analogues, cis- and trans-4-aminocrotonic acid (ACA) on GABA (A) receptor function and GABA uptake, together with the presence of p-1 subunit mRNA and putative GABAc receptors, were studied in primary cultures of neocortical neurons and cerebellar granule cells. Both isomers induced a Cl- influx, which was inhibited by bicuculline, t-butylbicyclophosphorothionate (TBPS), picrotoxinin (PTX), and gamma-hexachlorocyclohexane (gamma-HCH or lindane). [3H]-flunitrazepam binding was also increased by both isomers and this increase was inhibited by bicuculline. In neocortical neurons, the transisomer completely inhibited the [3H] GABA uptake, whereas the cis-isomer produced only a 25% inhibition at the highest concentration used. The possible presence of GABAc receptors was investigated only in neocortical cultures by using RT-PCR in order to detect the presence of the mRNA encoding the p-1 subunit which assembles to form homooligomeric Cl-channels. The results presented here show that p-1 subunits, and thus GABAc receptors, may represent a very minor population of GABA receptors in these neuronal preparations. We conclude that both GABA analogues may act as agonists at the GABA (A) receptors, although with very different potencies. |
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