Gonadotropin-releasing hormone, glutamate and estradiol interaction in the modulation of the reproductive cycle of the south american pains vizcacha (Lagostomus maximus)

INSERRA PIF, CHARIF SE, FIDEL V, SCHMIDT AR, CORTASA S, PROIETTO S, CORSO MC, DI GIORGIO NP, LUX-LANTOS V, HALPERIN J, VITULLO AD, & DORFMAN VB.

Mar del Plata

Congreso; LXIII Reunión Científica Anual. Sociedad Argentina de Investigación Clínica (SAIC),; 2018

Sociedad Argentina de Investigaicón Clínica (SAIC).

Lagostomus maximus shows peculiar reproductive features such as massive poliovulation and reactivation of the hypothalamic-pituitary-ovarian (HPO) axis during pregnancy with follicular recruitment and ovulation at mid-gestation. Its gonadotropin-releasing hormone (GnRH) neurons at preoptic (POA) and supraoptic (SON) areas express estrogen receptor alpha (ERalpha). Glutamate (GLU) modulates GnRH neurons through its specific receptor NMDA-R in an estradiol (E2) dependent manner. The aim of this work was to study the involvement of E2 on the glutamatergic system and its modulation on GnRH expression. Their involvement on HPO axis activation during gestation was evaluated. Adult vizcachas were used under three experimental conditions: 1) non-pregnant (NP), 2) early-pregnant (EP), mid-pregnant (MP), and term-pregnant (TP) females, and 3) NP ovariectomized (OVX) females injected with E2 (1mg/kg/day) during 5 days (OVX+E2). SHAM animals were used as controls. N=6 per group. E2 serum levels, and hypothalamic GnRH and NMDA-R were studied by ELISA, RIA, Western-blot, and immunofluorescence. MP females showed higher serum E2 levels, and GnRH and NMDA-R expression vs. EP & TP. Hypothalamic explants of NP incubated with GLU +/- GLU receptors antagonist showed significant GnRH delivery increments when NMDA-R was blocked (p