17-Beta-estradiol directly regulates the expression of adrenergic receptors and kisspeptin/GPR54 system in GT1-7 GnRH neurons.

Estradiol plays a critical role in the feedback regulation of reproduction, in part by modulating the neurosecretory activity of gonadotropin-releasing hormone (GnRH) neurons. While indirect effects of estradiol on GnRH neurons have been clearly demonstrated, direct actions are still controversial. In the current study, we examined direct effects of 17beta-estradiol upon the expression of receptors for afferent signals at the level of the GnRH neuron, using immortalized GT1-7 cells.

GABA inhibition of cyclic AMP production in immortalized GnRH neurons is mediated by calcineurin-dependent dephosphorylation of adenylyl cyclase 9.

The neurotransmitter gamma-aminobutyric acid (GABA) is an important modulator of gonadotropin-releasing hormone (GnRH), and consequently of reproduction. GABA, acting via ionotropic GABAA receptors, exerts a biphasic effect on GnRH secretion in immortalized GnRH cells. The initial increase in GnRH secretion is triggered by a sharp rise in [Ca2+]i, while the progressive decline of GnRH levels that follows is paralleled by reduced levels of intracellular cAMP.