Reproductive effects of phoenixin (911.8)

Abstract

Phoenixin is a peptide hormone identified by our group to be produced in the neuroendocrine hypothalamus and pituitary gland (J Neuroendocrinol 25:206,2013). We have demonstrated a direct pituitary action of phoenixin to augment GnRH‐stimulated LH secretion and that compromise of endogenous phoenixin production in hypothalamus delayed the onset of estrus in female rats, suggesting an important role for the peptide in reproductive function. We report here that phoenixin mRNA levels are significantly elevated in hypothalamus and anterior pituitary on diestrous day one when estrogen levels are at their lowest during the rat estrous cycle. In cultures of an immortalized mouse gonadotroph cell line, LβT2, phoenixin treatment for two hours increases Luteinizing Hormone β‐chain mRNA, as determined by real time polymerase chain reaction. Treatment of the cells with estradiol benzoate abrogates this effect. Additionally, ovariectomized animals treated with estradiol benzoate also show a trend toward a decrease in phoenixin gene expression in hypothalamus and anterior pituitary gland. These data demonstrate that phoenixin production and action may be controlled by ambient, gonadal steroid levels, and further support a physiologically relevant role for endogenous phoenixin in the control of gonadotropin release.Grant Funding Source: SLU President's Research Fund