Role of Na+ and Ca2+ Channels in the Preoptic LH Surge Generating Mechanism in Proestrous Rats

Endocrine Journal

SACHIKO AIBA¹  ATSUSHI FUKUSHIMA¹  AKANE SANO¹  FUKUKO KIMURA¹ 

[1] Department of Physiology, Yokohama City University School of Medicine

关键词: LH surge generator;    Preoptic area;    Na+ channels;    Ca2+ channels;    TTX;    Nifedipine;    Proestrous rat;   

DOI  :  10.1507/endocrj.50.145

学科分类：内分泌与代谢学

来源: Japan Endocrine Society

【 摘 要 】

References(39)Cited-By(2)We studied whether Na+ and Ca2+ channels are involved in the neural mechanism responsible for the surge of gonadotropin-releasing hormone (GnRH) in proestrous rats. In experiment 1, female rats in proestrus were ip injected at 1345 h with pentobarbital sodium (35 mg/kg) to block spontaneous surge of LH and electrical stimulation was applied between 1400 and 1600 h to the preoptic area (POA) together with POA injection of 0.5 μl saline containing the Na+ channel blocker tetrodotoxin (TTX) at a concentration of 1 μM, 2 μM, or 5 μM. Since 5 μM TTX completely blocked the increase in serum LH concentrations evoked by the POA stimulation, we used this concentration in experiment 2 to observe the TTX effect on the spontaneous LH surge. In experiment 2, bilateral injections of 1.5 μl of 5 μM TTX at 1430 h in the POA in proestrous rats postponed the peak time and reduced the peak level of the LH surge. In experiment 3, bilateral injections of 1.5 μl of 5 μM L-type Ca2+ channel blocker nifedipine at 1430 h in the POA completely blocked the LH surge. Since the cell bodies of GnRH neurons are primarily concentrated in the POA in rats, these results suggest that both voltage-sensitive Na+ channels and Ca2+ channels contribute to the generation of action potentials at GnRH cell bodies for the surge release of GnRH.

【 授权许可】

Unknown