17β-estradiol and progesterone regulate multiple progestin signaling molecules in the anteroventral periventricular nucleus, ventromedial nucleus and sexually dimorphic nucleus of the preoptic area in female rats.

Recent work identified novel progestin signaling molecules, including progesterone receptor membrane component 1 (Pgrmc1), Pgrmc2, serpine mRNA binding protein 1 (Serbp1), progestin and adiponectin receptors 7 (Paqr7) and Paqr8. These molecules mediate rapid progesterone (P(4)) effects in non-neural tissue and we recently mapped their expression in the brain. Many rapid effects of P(4) require 17β-estradiol (E(2)) and P(4) priming; therefore, we examined the effects of ovarian hormones on the expression of these non-classical progestin signaling molecules. We focused specifically on the anteroventral periventricular nucleus (AVPV), the sexually dimorphic nucleus of the preoptic area (SDN-POA) and the ventrolateral portion of the ventromedial nucleus (VMNvl). These brain nuclei are important for female reproduction. Ovariectomized adult female rats were implanted with capsules containing sesame oil or E(2), and injected 48 h later with sesame oil or P(4). Brains were collected 8 h later and RNA was isolated from the AVPV, SDN-POA and VMNvl. We assessed the effects of ovarian hormones on mRNA levels using quantitative polymerase chain reaction (QPCR). In the AVPV, Serbp1 mRNA levels were increased by P(4) in the presence of E(2), and Paqr8 was downregulated by P(4) alone. In the SDN-POA, combined E(2) and P(4) increased Pgrmc1 and Serbp1 mRNA levels, and E(2) alone increased Paqr8 mRNA levels. Finally, in the VMNvl, P(4) increased mRNA levels encoding Pgrmc1, Pgrmc2 and Serbp1, and the combination of E(2) and P(4) increased Pgrmc1 and Serbp1 mRNA levels. Paqr7 was not regulated by E(2) or P(4) in any brain region examined. In summary, we showed that ovarian hormones regulate novel progestin signaling molecules in brain regions important for the neuroendocrine control of reproduction.