Grid1 Regulates the Onset of Puberty in Female Rats
Abstract The present study aimed to investigate whether Grid1, encoding the glutamate ionotropic receptor delta type subunit 1(GluD1), influences the onset of puberty in female rats. First, we detected the expression of Grid1 mRNA and its protein in the hypothalamus from infancy to puberty. Second, we evaluated the suppression of Grid1 expression by Lentivirus-Grid1 (LV-Grid1) in primary hypothalamus cells through measuring the expression level of Grid1. Finally, LV-Grid1 was intracerebroventricular injected (ICV) into 21-day-old rats and to investigate the effect of Grid1 suppression on puberty onset in vivo. Results showed that GluD1 immunoreactivity could be detected in the arcuate nucleus (ARC), paraventricular nucleus (PVN), and periventricular nucleus (PeN). Grid1 mRNA levels were the lowest at prepuberty. Treatment of hypothalamic neurons with LV-Grid1 decreased the mRNA expression levels of Grid1 and Rfrp-3 (encoding RFamide-related peptide 3, RFRP 3), but increased that of Gnrh (encoding gonadotropin-releasing hormone, GnRH). After 7 days of ICV LV-Grid1 into rats, the Grid1 mRNA was significantly reduced (by 46%), Gnrh mRNA expression was significantly increased, but Rfrp-3 mRNA levels were decreased. The time of rat vaginal opening (VO) was earlier in the LV-Grid1 group; the concentrations of luteinizing hormone (LH), estradiol (E2), and progesterone (P4) in serum were significantly increased; and the ovaries were significantly larger. Our study revealed that Grid1 affects the onset of puberty by regulating the level of GnRH and RFRP3.