Hypothalamic GnRH expression and pulsatility depends on a balance of prolactin receptors in the plains vizcacha, Lagostomus maximus

CORTASA SA; SCHMIDT AR.; PROIETTO S; CORSO MC; INSERRA PIF; DI GIORGIO NP; LUX-LANTOS VA; VITULLO AD; HALPERIN J; DORFMAN VB

Journal of Comparative Neurology

Wiley

Año: 2023

1096-9861

In mammals, gestation is considered a physiological hyperprolactinemia status. Prolactin (PRL)is one of the modulators of gonadotropin-releasing hormone (GnRH) neurons function. TheSouth American plains vizcacha (Lagostomus maximus) is a unique model to study the regulationof hypothalamic GnRH neurons by direct and indirect steroid-dependent pathways. The aim wasto characterize the hypothalamic expression of endocrine markers in vizcacha during gestation, aswell as their response to experimental induced hiperprolactinemia. The possible involvement ofPRL regulatory pathways on GnRH in the context of hypothalamic and pituitary reactivation inmid-gestating vizcachas was discussed. Using two in vivo approaches, we determined changes inthe hypothalamic expression and distribution of prolactin receptor (PRLR), tyrosine hydroxylase(TH), and dopamine type 2 receptor. A significant increment in the number of tuberoinfundibulardopaminergic (TIDA) neurons was determined in the arcuate nucleus from early to termpregnancy. On the other hand, at preoptic area, the number of both TH+PRLR+ andGnRH+PRLR+ double-labeled neurons significantly decreased at mid-pregnancy probablyallowing the recovery of GnRH expression indicating that both types of neurons may representthe key points of prolactin indirect and direct pathways modulating GnRH. Moreover, in a modelof induced hyperprolactinemic vizcachas, the inhibitory effect of prolactin on GnRH at bothexpression and delivery levels were confirmed. These results suggest the concomitantparticipation of both prolactin regulatory pathways on GnRH modulation and pinpoint the keyrole of prolactin on GnRH expression enabling the recovery of the hypothalamic activity duringthe gestation in this species.