Asymmetrical effects of the unilateral implant of pilocarpine on the preoptic-anterior hypothalamic area on spontaneous ovulation of the adult rat.
The effects on ovulation at the next estrus after unilaterally implanting pilocarpine in the preoptic-anterior hypothalamic area (POA-AHA) of rats on each day of the estrous cycle were analyzed. Implantation on the left side of POA-AHA on the day of estrus blocked ovulation in all animals, whereas implantation on the right side did not (0/5 vs. 4/4, P < 0.05). Implantation on diestrus 1 or 2 on either side of the POA-AHA blocked ovulation. Implantation on the right side of the POA-AHA at the day of proestrus blocked ovulation (1/6 animals ovulated), while 10/12 with pilocarpine on the left side ovulated (P < 0.05). The administration of 3.7 micrograms of GnRH at 13:00 h on the expected day of proestrus induced ovulation in 36/42 treated animals. In rats with a pilocarpine implant, the injection of estradiol benzoate on diestrus 2 restored ovulation only in those animals with the pilocarpine implant placed in the left side of the POA-AHA, performed on the day of estrus. The results support the previous statements that in the adult rat POA-AHA, the cholinergic mechanism regulating preovulatory GnRH release, is lateralized. In addition, at the beginning of the estrous phase, the POA-AHA-cholinergic system needs to remain undisturbed for normal ovulation to take place at the next estrus.
López
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Unidad de Investigación en Biología de la Reproducción, Laboratorio de Neuroendocrinología, Facultad de Estudios Superiores Zaragoza, UNAM, México D.F.
Cruz
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ME
Domínguez
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R
D000818:Animals; D007025:Anterior Hypothalamic Nucleus / Q000187:drug effects* / Q000502:physiology*; D004343:Drug Implants; D005260:Female; D018721:Muscarinic Agonists / Q000008:administration & dosage* / Q000494:pharmacology; D010060:Ovulation / Q000187:drug effects* / Q000502:physiology*; D010862:Pilocarpine / Q000008:administration & dosage* / Q000494:pharmacology; D011301:Preoptic Area / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D004343:Drug Implants; D018721:Muscarinic Agonists; D010862:Pilocarpine