A comparative analysis of the neuroendocrine mechanisms regulating ovulation, affected by a unilateral implant of atropine in the preoptic-anterior hypothalamic area, in intact and hemiovariectomized adult rats.
The effects were analysed of a unilateral implant of atropine on ovulation in intact and hemiovariectomized adult rats, together with the response of the atropine-implanted rats to hormone replacement. An outer cannula directed to the left or right preoptic (POA)-anterior-hypothalamic area (AHA) was implanted into cyclic adult rats. A group of animals in oestrus was hemiovariectomized and some were also implanted with a cannula. After two consecutive 4-day cycles, the hemiovariectomized animals were implanted with atropine (23 +/- 4 micrograms) or cholesterol (25 +/- 2 micrograms) on the day of oestrus. Atropine implanted into the left side of the POA-AHA blocked ovulation and compensatory ovarian hypertrophy, whilst implants in the right side had no effects. Administration of gonadotrophin-releasing hormone (GnRH; 3.7 micrograms/kg) at 13.00 h on the expected day of pro-oestrus induced ovulation in six out of seven treated animals. Of 19 rats with an implant of atropine in the left side of the POA-AHA, one ovulated after treatment with pregnant mare serum gonadotrophin (PMSG) on oestrus, or oestradiol benzoate or human chorionic gonadotrophin (hCG) on day 2 of dioestrus. The effects on ovulation of a unilateral implant of atropine into the POA-AHA of cyclic adult rats and the responses of such rats to GnRH, PMSG, hCG and oestradiol benzoate replacement were also studied. Ovulation was induced in rats with a unilateral implant of atropine and which had been treated with GnRH or hCG at 13.00 h on the expected day of pro-oestrus after the implant.(ABSTRACT TRUNCATED AT 250 WORDS)
Cruz
M E
ME
Biology of Reproduction Research Unit, Escuela Nacional de Estudios Profesionales Zaragoza, U.N.A.M., México D.F.
Castro
J
J
Domínguez
R
R
D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000502:physiology; D006062:Gonadotropins / Q000502:physiology; D007032:Hypothalamus, Anterior / Q000033:anatomy & histology / Q000502:physiology*; D010052:Ovariectomy; D010060:Ovulation / Q000187:drug effects* / Q000502:physiology*; D011301:Preoptic Area / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains
D006062:Gonadotropins; D007987:Gonadotropin-Releasing Hormone; D001285:Atropine