Restricted accessResearch articleFirst published online 2006-09
Hyperpolarization-Activated Cation Channels Are Expressed in Rat Hypothalamic Gonadotropin-Releasing Hormone (GnRH) Neurons and Immortalized GnRH Neurons
Objectives:The current research was conducted to determine whether hyperpolarization-activated cyclic nucleotide-gated (HCN1-4) channels are expressed in gonadotropin-releasing hormone (GnRH) neurons in the female rat hypothalamus and immortalized GnRH neurons (GT1-7 cells).
Methods:Double-lavel fluorescence immunohistochemistry was used to colocalized HCN1-4 channels and GnRH in GnRH neurons in the female rat hypothalamus. Reverse transcriptase-polymerase chain reaction (RT-PCR), Westerns blotting, and immunocytochemistry were used to analyze HCN channel gene expression in GT1-7 cells.
Results:Double-label fluorescence immunohistochemistry showed that 43% of hypothalamic GnRH neurons immunostained for HCN2 and 90% of GnRH neurons immunostained for HCN3. RT-PCR and Western blot showed expression of all four HCN channel subunits in GT1-7 cells. Double-label immunochemistry showed cytoplasmic immunostaining of HCN2 and HCN3 in GT1-7 cells.
Conclusions:This study demonstrates for the first time that HCN channels are expressed in GnRH neurons in the rat hypothalamus and GT1-7 cells. Our research supports the hypothesis that HCN channels may be involved in electrical bursting activity and pulsatile GnRH secretion in endogenous GnRH neurons and GT1-7 cells.
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