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

CORTASA, SANTIAGO A.; SCHMIDT, ALEJANDRO R.; PROIETTO, S.; CORSO, M.C.; INSERRA PIF; DI GIORGIO NP; LUX LANTOS VAR; VITULLO AD; HALPERIN J; DORFMAN VB

JOURNAL OF COMPARATIVE NEUROLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Lugar: New York; Año: 2023

0021-9967

In mammals, gestation is considered a physiological hyperprolactinemia status. Prolactin (PRL) is one of the modulators of gonadotropin-releasing hormone (GnRH)neurons function. The South American plains vizcacha (Lagostomus maximus) is a uniquemodel to study the regulation of hypothalamic GnRH neurons by direct and indirectsteroid-dependent pathways. The aim was to characterize the hypothalamic expression of endocrine markers in vizcacha during gestation as well as their response toexperimental induced hyperprolactinemia. The possible involvement of PRL regulatory pathways on GnRH in the context of hypothalamic and pituitary reactivation inmid-gestating vizcachas was discussed. Using two in vivo approaches, we determinedchanges in the hypothalamic expression and distribution of prolactin receptor (PRLR),tyrosine hydroxylase (TH), and dopamine type 2 receptor. A significant incrementin the number of tuberoinfundibular dopaminergic (TIDA) neurons was determinedin the arcuate nucleus from early to term pregnancy. On the other hand, at preoptic area, the number of both TH+PRLR+ and GnRH+PRLR+ double-labeled neuronssignificantly decreased at mid-pregnancy probably allowing the recovery of GnRHexpression indicating that both types of neurons may represent the key points of PRLindirect and direct pathways modulating GnRH.Moreover, in a model of induced hyperprolactinemic vizcachas, the inhibitory effect of PRL on GnRH at both expression anddelivery levels were confirmed. These results suggest the concomitant participationof both PRL regulatory pathways on GnRH modulation and pinpoint the key role ofPRL on GnRH expression enabling the recovery of the hypothalamic activity during thegestation in this species.