Differences in the ovulatory response to unilateral lesions in the preoptic or anterior hypothalamic area performed on each day of the estrous cycle of adult rats.

The effects of a unilateral lesion made on the right or left side of the preoptic area (POA) or anterior hypothalamic area (AHA) made on each day of the estrous cycle, were analyzed. Ovulation rate decreased among the animals with a lesion performed on the day of estrous on the right side of POA (1/7 vs. 7/7, p < 0.05) and in animals with a lesion on diestrus-1 on each side AHA (4/9, 4/9 vs. 7/7, p < 0.05). Ovulation was restored by GnRH injection, while estradiol benzoate administration restored ovulation only in rats with a lesion on the right side of POA or AHA. We suggest that the participation of POA and AHA in the regulation of ovulation is asymmetric, lateralized, and changes during the estrous cycle. The estrogen-positive feedback needs the integrity of the left side of AHA on diestrus-1.