Definition of the estrogen negative feedback pathway controlling the GnRH pulse generator in female mice

The mechanisms underlying the homeostatic estrogen negative feedback pathway central to mammalian fertility have remained unresolved. Direct measurement of gonadotropin-releasing hormone (GnRH) pulse generator activity in freely behaving mice with GCaMP photometry demonstrated striking estradiol-dependent plasticity in the frequency, duration, amplitude, and profile of pulse generator synchronization events. Mice with Cre-dependent deletion of ESR1 from all kisspeptin neurons exhibited pulse generator activity identical to that of ovariectomized wild-type mice. An in vivo CRISPR-Cas9 approach was used to knockdown ESR1 expression selectively in arcuate nucleus (ARN) kisspeptin neurons. Mice with >80% deletion of ESR1 in ARN kisspeptin neurons exhibited the ovariectomized pattern of GnRH pulse generator activity and high frequency LH pulses but with very low amplitude due to reduced responsiveness of the pituitary. Together, these studies demonstrate that estrogen utilizes ESR1 in ARN kisspeptin neurons to achieve estrogen negative feedback of the GnRH pulse generator in mice. Estrogen secreted by the ovary controls how the brain drives pulsatile reproductive hormone secretion. The authors show that in mice, estrogen receptor alpha within a specific population of hypothalamic kisspeptin neurons is the principal pathway through which estrogen brings about this classic negative feedback pathway common to all mammals.

Automated summary

This study reveals the mechanisms underlying the homeostatic estrogen negative feedback pathway and demonstrates the crucial role of estradiol-dependent plasticity in pulse generator synchronization events. The study also provides experimental evidence that estrogen receptor alpha in hypothalamic kisspeptin neurons is the principal pathway for estrogen negative feedback in mice.