Phasic synaptic incorporation of GluR2-lacking AMPA receptors at gonadotropin-releasing hormone neurons is involved in the generation of the luteinizing hormone surge in female rats

Abstract

Reproductive success depends on a robust and appropriately timed preovulatory luteinizing hormone (LH) surge, which is induced by the activation of gonadotropin-releasing hormone (GnRH) neurons in response to positive feedback from increasing estrogen levels. Here we document an increase in postsynaptic GluR2-lacking Ca2+ -permeable AMPA-type glutamate receptors (CP-AMPARs) at synapses on GnRH neurons on the day of proestrus in rats, coincident with the increase in estrogen levels. Functional blockade of CP-AMPARs depressed the synaptic responses only on the day of proestrus and concomitantly attenuated the LH surge. Thus, the phasic synaptic incorporation of postsynaptic CP-AMPARs on GnRH neurons is involved in the generation of the LH surge.

Keywords: 1-naphthyl acetyl spermine; 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; 6-cyano-7-nitroquinoxaline-2,3-dione; ANOVA; CNQX; CP-AMPA receptor; CP-AMPARs; EGTA; GFP; GnRH; HEPES; LH; NASPM; OVX; PPR; Trafficking; analysis of variance; calcium permeable AMPA-type glutamate receptors; estrus cycle; ethylene glycol tetraacetic acid; gonadotropin-releasing hormone; green fluorescent protein; luteinizing hormone; mEPSCs; miniature excitatory postsynaptic currents; ovariectomized; paired-pulse ratio; synapse.