Expression profile of RFRP-3 gene in hypothalamic tissue and its relationship with reproductive hormones across phases of the estrous cycle in female rats

The expression profile of RFRP-3 during the different phases of the estrous cycle and its relationship with reproductive hormones were studied in 36 adult female Wister rats. Phases of the estrous cycle were characterized by visual observation of the vagina and vaginal exfoliated cell cytology. The expression profile of the RFRP-3 gene in the hypothalamic tissue was evaluated by real-time qPCR. Reproductive hormones (LH, FSH, estrogen, and progesterone) were measured from plasma by enzyme immunoassay. The expression level of RFRP-3 was significantly higher (P < 0.01) during diestrus compared to other phases of the estrous cycle. The lowest expression level was detected during estrus and metestrus. The highest level of LH was detected during the proestrus and metestrus and the lowest during the diestrus. Higher expression of RFRP 3 during diestrus is consistent with the higher level of estrogen, however, the lower expression of RFRP 3 during estrus and met estrus did not corroborate with the level of estrogen. The findings of this research work revealed significant up-regulation of RFRP-3 during the estrous cycle together with higher estrogen level. Therefore it can be concluded that higher expression of RFRP 3 may lead to the suppression of the HPG axis during diestrus in rats and estrogen may be involved in the regulation of RFRP-3.