It is well-established that liver receptor homolog 1 (LRH-1/NR5A2) regulates the ovarian function and is required for ovulation and luteinization in mice. In the present experiment, we showed that LRH-1 is required to control vascular changes during ovulation, a novel mechanism of action of this orphan nuclear receptor.
Liver receptor homolog 1 (LRH-1/NR5A2) is a key regulator of ovarian function, and recently, it has been suggested that it may regulate changes in follicular angiogenesis, an important event during the ovulatory process and luteal development. In the present experiment, the objective was to determine whether conditional depletion of LRH-1 in mice granulosa cells modified vascular changes during the periovulatory period and to explore the possible mechanisms of this modification. We generated mice (22- to 25-day-old) with specific depletion of LRH-1 in granulosa cells by crossing Lrh1 floxed (Lrh1 f/f) mice with mice expressing Cre-recombinase driven by the anti-Müllerian type II receptor (Amhr2-cre; conditional knockout or cKO mice). We showed that preovulatory follicles of LRH-1 cKO mice had a reduced number of endothelial cells in the theca cell layer at 8 h after human chorionic gonadotropin treatment compared with control (CON) mice. Additionally, mRNA and protein expression of leptin receptor (LEPR), a protein that stimulates angiogenesis in a vascular endothelial growth factor-A (VEGFA)-dependent manner, and teratocarcinoma-derived growth factor-1 (TDGF1), which may directly stimulate endothelial cell function, were reduced in LRH-1 cKO mice as compared to CON after the LH surge. These results showed that LRH-1 is necessary for the correct vascular changes that accompany ovulation in mice and that this effect may be regulated through VEGFA-dependent and VEGFA-independent pathways mediated by LEPR and TDGF1.