期刊
JOURNAL OF NEUROCHEMISTRY
卷 103, 期 6, 页码 2342-2353出版社
WILEY
DOI: 10.1111/j.1471-4159.2007.04945.x
关键词
5-HT3 receptors; CA3 pyramidal neurons; GABAergic; mIPSCs; hippocampus; ion permeability; postnatal development
Serotoninergic modulation of GABAergic mIPSCs was investigated in immature (postnatal 12-16-days old) rat CA3 pyramidal neurons using a conventional whole-cell patch clamp technique. Serotonin or 5-hydroxytryptamine (5-HT) (10 mu mol/L) transiently and explosively increased mIPSC frequency with a small increase in the current amplitude. However, 5-HT did not affect the GABA-induced postsynaptic currents, indicating that 5-HT acts presynaptically to facilitate the probability of spontaneous GABA release. The 5-HT action on GABAergic mIPSC frequency was completely blocked by 100 nmol/L MDL72222, a selective 5-HT3 receptor antagonist, and mimicked by mCPBG, a selective 5-HT3 receptor agonist. The 5-HT action on GABAergic mIPSC frequency was completely occluded either in the presence of 200 mu mol/L Cd2+ or in the Na+-free external solution, suggesting that the 5-HT3 receptor-mediated facilitation of mIPSC frequency requires a Ca(2+)influx passing through voltage-dependent Ca(2+)channels from the extracellular space, and that presynaptic 5-HT3 receptors are less permeable to Ca2+. The 5-HT action on mIPSC frequency in the absence or presence of extracellular Na+ gradually increased with postnatal development. Such a developmental change in the 5-HT3 receptor-mediated facilitation of GABAergic transmission would play important roles in the regulation of excitability as well as development in CA3 pyramidal neurons.
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