Involvement of G Protein-Coupled Receptor 30 (GPR30) in Rapid Action of Estrogen in Primate LHRH Neurons

Previously, we have reported that 17β-estradiol (E2) induces an increase in firing activity of primate LH-releasing hormone (LHRH) neurons. The present study investigates whether E2 alters LHRH release as well as the pattern of intracellular calcium ([Ca2+]i) oscillations and whether G protein-coupled receptor 30 (GPR30) plays a role in mediating the rapid E2 action in primate LHRH neurons. Results are summarized: 1) E2, the nuclear membrane-impermeable estrogen, estrogen-dendrimer conjugate, and the plasma membrane-impermeable estrogen, E2-BSA conjugate, all stimulated LHRH release within 10 min of exposure; 2) whereas the estrogen receptor antagonist, ICI 182,780, did not block the E2-induced LHRH release, E2 application to cells treated with pertussis toxin failed to induce LHRH release; 3) GPR30 mRNA was expressed in olfactory placode cultures, and GPR30 protein was expressed in a subset of LHRH neurons; 4) pertussis toxin treatment blocked the E2-induced increase in [Ca2+]i oscillations; 5) knockdown of GPR30 in primate LHRH neurons by transfection with small interfering RNA (siRNA) for GPR30 completely abrogated the E2-induced changes in [Ca2+]i oscillations, whereas transfection with control siRNA did not; 6) the estrogen-dendrimer conjugate-induced increase in [Ca2+]i oscillations also did not occur in LHRH neurons transfected with GPR30 siRNA; and 7) G1, a GPR30 agonist, resulted in changes in [Ca2+]i oscillations, similar to those observed with E2. Collectively, E2 induces a rapid excitatory effect on primate LHRH neurons, and this rapid action of E2 appears to be mediated, in part, through GPR30