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GABAC receptor mediated inhibition in acutely isolated neurons of the rat dorsal lateral geniculate nucleus

2004; Elsevier BV; Volume: 63; Issue: 2 Linguagem: Inglês

10.1016/j.brainresbull.2004.01.003

1873-2747

Katja Schlicker, Mathias Boller, M. Schmidt,

Neuroendocrine regulation and behavior

In the dorsal lateral geniculate nucleus (dLGN), GABAC receptors seems to be specifically expressed by local GABAergic interneurons. Although the presence of GABAC receptors has been demonstrated, a quantitative estimation of their contribution to inhibition in dLGN is lacking. Because the amount of inhibition mediated by these receptors might reflect their functional importance we performed whole-cell patch clamp recordings from dLGN cells acutely dissociated from brain slices. We focally applied the GABA receptor agonist muscimol and quantified effects mediated through either GABAC or GABAA receptors. Because their basic dendritic morphology was preserved, we tried to morphologically differentiate between thalamocortical cells and local interneurons. In the majority of multipolar cells, representing thalamocortical projection neurons, the specific GABAA receptor antagonist bicuculline completely blocked muscimol induced currents. In contrast, in most of the bipolar cells, representing interneurons, bicuculline blocked only 70–80% of the muscimol induced currents. The remaining currents were blocked by co-application of TPMPA, a specific GABAC receptor antagonist, or picrotoxin, an unspecific GABAA and GABAC receptor blocker. The latter neurons were also sensitive to the selective GABAC receptor agonist cis-aminocrotonic acid. These results indicate that in those dLGN neurons that express GABAC receptors, these receptors contribute considerably to GABAergic inhibitory inputs.