P-222: Expression of RFamide-Related Peptide-3 and KiSS-1 mRNA in The Hypothalamus of Pregnant Rat

Background: There is no follicular development during pregnancy in the rat comparable to the changes of the estrous cycle. RFamide-related peptide-3 (RFRP-3) and kisspeptin were recognized as regulator of gonadotropin releasing hormone (GnRH) and luteinizing hormone (LH) secretion in several species, including the rat. The aim of the present study was to evaluate the relative expression of RFRP-3 and KiSS-1 mRNA in the hypothalamus of pregnant rats. Materials and Methods: Eighteen adult pregnant Sprague-Dawley rats (3-4 months old) were decapitated, and the whole hypothalamus was dissected at the age of 7, 14, and 21 days of pregnancy (n=6). The exact day of the rat pregnancy was confirmed using the vaginal smear method2. Four female non-pregnant rats were ovariectomized and assigned as control group. The dorsomedial hypothalamic nucleus (DMH) for detection of RFRP-3 mRNA and arcuate nucleus (ARC) for detection of KiSS-1 mRNA were separated from hypothalamus. Then relative expression of RFRP-3 and KiSS-1 mRNA were compared using real-time PCR method between control and pregnant groups. The data were subjected to the test of normality and analyzed by one-way ANOVA (SAS 9.1, SAS Institute Inc., NC), and mean separation was performed by Tukey&#039;s test at p=0.01. Results: The mean and SE of relative expression of RFRP-3 in DMH did not change during pregnancy (day 7, 40.8 ± 16.2%; day 14, 73.9 ± 17.7%; day 21, 49.9 ± 13.2%; p>0.01). However, the relative expression of KiSS-1 in ARC was the highest in day 7 of pregnancy and decreased up to day 21 of pregnancy (day 7, 17.1 ± 4.4%; day 14, 13.8 ± 5.3%; day 21, 4.3 ± 4.0%; p<0.01). Conclusion: Decrease of the GnRH and LH secretion during the pregnancy of rat may be controlled by constant expression of RFRP-3 mRNA and decreasing pattern of KiSS-1 mRNA expression.