Erythropoietin-producing hepatocellular receptor A7 restrains estrogen negative feedback of luteinizing hormone via ephrin A5 in the hypothalamus of female rats.

We have previously shown that systemic injection of erythropoietin-producing hepatocellular receptor A7 (EPHA7)-Fc raises serum luteinizing hormone (LH) levels before ovulation in female rats, indicating the induction of EPHA7 in ovulation. In this study, we aimed to identify the mechanism and hypothalamus-pituitary-ovary (HPO) axis level underlying the promotion of LH secretion by EPHA7. Using an ovariectomized (OVX) rat model, in conjunction with low-dose 17β-estradiol (E) treatment, we investigated the association between EPHA7-ephrin (EFN)A5 signaling and E negative feedback. Various rat models (OVX, E-treated OVX, and abarelix treated) were injected with the recombinant EPHA7-Fc protein through the caudal vein to investigate the molecular mechanism underlying the promotion of LH secretion by EPHA7. was observed strongly expressed in the arcuate nucleus of the female rat by using RNAscope in situ hybridization. Our results indicated that E, combined with estrogen receptor (ER)α, but not ERβ, inhibited and gonadotropin-releasing hormone 1 ( expressions in the hypothalamus. In addition, the systemic administration of EPHA7-Fc restrained the inhibition of and by E, resulting in increased and expressions in the hypothalamus as well as increased serum LH levels. Collectively, our findings demonstrated the involvement of EPHA7-EFNA5 signaling in the regulation of LH and the E negative feedback pathway in the hypothalamus, highlighting the functional role of EPHA7 in female reproduction.