Regulation of luteinizing hormone receptor in hippocampal neurons following different long-lasting treatments of castrated adult rats.

The aim of this study was to investigate the effects of different Luteinizing hormone (LH) and steroid hormones levels on LH receptor (LHR) expression in the hippocampal cells. Rats (24 males and 24 females) were assigned to four groups: one control and three experimental [gonadectomy (GDX), gonadectomy + gonadotropin releasing hormone analogue (GDX+GnRHa) and GDX+GnRHa+estradiol (E2) or testosterone (T)] independently for each gender. All experimental rats were gonadectomized; then GnRHa was administrated to GDX+GnRHa group, and GnRHa plus steroid hormone to GDX+GnRHa+E2 or T group in both genders for four-month. LHR mRNA expression and its protein level in hippocampal cells were measured using QRT-PCR and Western blotting. Quantification of mRNA revealed a decrease in LHR transcripts level in GDX+GnRHa group of females. A significant change was observed between GDX groups and GDX+GnRHa+E2 or T versus GDX+GnRHa group in females. High levels of LH decreased significantly the immature isoform of LHR in GDX group compared to control group in both genders, but low LH concentrations in GDX+GnRHa group induced immature LHR isoform production only in females. Therefore increased LH concentration induces production of incomplete LHR transcripts in hippocampal cells and decreases immature LHR at the protein level. This implies that LH decreases the efficiency of translation through either producing non-functional LHR molecules or preventing their translation.