Effects of stereotactic surgery on the anterior hypothalamus (HA) on the estrous cycle: Role of the dopaminergic system in spontaneous ovulation in the rat

We evaluated the function of dopaminergic receptors (DAR) of the anterior hypothalamus (AH) on the estral cycle (EC) regulation and spontaneous ovulation by a single microinjection (MI) with the dopaminergic antagonist haloperidol (HLP) in adult rats. One hundred thirty nine rats that exhibit forth-day estral cycles (cyclic animals: CA) received a stereotaxic surgery (STXS) on the right, left or both AH sides and were distributed in three different groups with a MI of 1 µL of: HLP (15 µg) or dimethyl-sulfoxide (vehicle) or other false MI group. All the animals with STXS were sacrificed in next vaginal estrus (VE) exhibited and the ova shed (OS) counted. In sixteen AC, the OS were counted at VE and forming a control group. The STXS affected the animals EC: just 59/139 exhibited a short EC (SEC) with 4.6±0.1 days compared with 80/139 that exhibited a long EC (LEC) of 13.6±0.2 days. False or HLP MI diminished OS just in animals exhibiting a SEC. STXS affects neuroendocrine processes controlling EC length when cutting dorsal connections to AH. The DAR of the AH participate on ovarian mechanisms of follicular selection.