Role of orexins in the hypothalamic-pituitary-ovarian relationships

SILVEYRA, P.; CATALDI, N.I.; LUX-LANTOS, V.; LIBERTUN,C.

Acta Physiologica (Scandinavica)

Wiley-Blackwell Publishing

Lugar: Hoboken, NJ ; Año: 2009 vol. 198 p. 355 - 360

1748-1708

Appropriate nutritional and vigilance states are needed for reproduction. We hypothesized that orexins may play a role in this integration. We determined the expression of preprorexin (PPO), Orexin 1 receptor (OX1) and Orexin 2 receptor (OX2) in brain and pituitary in female cycling rats. OX1 and OX2, by Real Time RT-PCR, increased only in hypothalamus and pituitary, at 17:00 h-23:00 h of proestrus. PPO increased only in hypothalamus in the evening of proestrus. Cetrorelix or Pentobarbital prevented the increases of OX1 and OX2 in pituitary, but left OX1, OX2 and PPO brain expression unchanged. Thus, we described the influence of the hormonal milieu of proestrus on the orexinergic system. In addition OX1 and OX2 expression in the ovary increased between 17:00 h and 23:00 h of proestrus in coincidence with gonadotropins peaks; PPO was not detected in this tissue. Cetrorelix or Nembutal prevented these increases while blunting gonadotropins. Furthermore, blocking of OX1 (by SB-334867-A) or OX2 (by JNJ-10397049) during proestrous afternoon decreased serum gonadotropins and reduced ova number in the oviduct the following morning. Finally, we found that OX1 expression in hypothalamus and adenohypophysis is under the influence of anatomical area, estradiol and the time (afternoon of proestrus) of the day. No entiendo We have demonstrated that information from the sexual hormonal milieu of proestrous afternoon impacts on various components of the orexinergic system; alertness on this particular night of proestrus would be of importance for successful reproduction.