Voltage-gated Ca2+ channel mRNAs and T-type Ca2+ currents in rat gonadotropin-releasing hormone neurons

Gonadotropin-releasing hormone (GnRH) neurons play a pivotal role in the neuroendocrine regulation of reproduction. We have previously reported that rat GnRH neurons exhibit voltage-gated Ca2+ currents. In this study, oligo-cell RT-PCR was carried out to identify subtypes of the α1 subunit of voltage-gated Ca2+ channels in adult rat GnRH neurons. GnRH neurons expressed mRNAs for all five types of voltage-gated Ca2+ channels. For T-type Ca2+ channels, α1H was dominantly expressed in GnRH neurons. Electrophysiological analysis in acute slice preparations revealed that GnRH neurons from adult rats exhibited T-type Ca2+ currents with fast inactivation kinetics (~20 ms at −30 mV) and a time constant of recovery from inactivation of ~0.6 s. These results indicate that rat GnRH neurons express subtypes of the α1 subunit for all five types of voltage-gated Ca2+ channel, and that α1H was the dominant subtype in T-type Ca2+ channels.