Endocrine pathogenesis of postweaning anestrus in swine: response of the persistently anestrous sow to hormonal stimuli.
The endocrine function of the individual components of the hypothalamo-hypophyseal-ovarian axis of the postweaning anestrous sow was evaluated by monitoring the sow's response to exogenous estradiol, gonadotropin releasing hormone (GnRH), and gonadotropins. Sows (4 to 6/group) not returning to estrus by 42.8 +/- 3.1 days after weaning were assigned to 1 of the following treatments: 10 micrograms of estradiol benzoate (EB)/kg of body weight; 200 micrograms of GnRH, 1,000 IU of pregnant mare's serum gonadotropin (PMSG); 1,000 IU of human chorionic gonadotropin (HCG); or 4 ml of saline solution plus 2 ml of corn oil. A preovulatory-like surge of luteinizing hormone [(LH) greater than 12 hours in duration] was observed in all weaned sows treated with EB. All EB-treated sows exhibited estrus and ovulated but none conceived. Sows given GnRH had transiently increased (less than 3 hours) LH concentrations that were not associated with estrus or ovulation. Treatment with PMSG caused an increase in peripheral concentrations of 17 beta-estradiol that was followed by an LH surge, estrus, ovulation, and conception. Treatment with HCG caused an increase in circulating concentrations of 17 beta-estradiol that was accompanied by a surge of LH in some sows and ovulation in all sows. Not all sows treated with HCG exhibited estrous behavior, but conception occurred in 2 of 3 sows that were mated at estrus. None of the sows treated with saline plus corn oil had consistent changes in circulatory concentrations of 17 beta-estradiol or LH and none exhibited estrus or ovulated.(ABSTRACT TRUNCATED AT 250 WORDS)
D000780:Anestrus / Q000187:drug effects*; D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004958:Estradiol / Q000097:blood / Q000494:pharmacology*; D004971:Estrus / Q000187:drug effects*; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000494:pharmacology; D006062:Gonadotropins / Q000494:pharmacology*; D006064:Gonadotropins, Equine / Q000494:pharmacology; D006728:Hormones / Q000494:pharmacology; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects; D007247:Infertility, Female / Q000209:etiology / Q000662:veterinary*; D007986:Luteinizing Hormone / Q000097:blood; D010060:Ovulation / Q000187:drug effects; D010062:Ovulation Induction / Q000662:veterinary; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology*; D011247:Pregnancy; D013552:Swine; D013553:Swine Diseases / Q000209:etiology*
D006063:Chorionic Gonadotropin; D006062:Gonadotropins; D006064:Gonadotropins, Equine; D006728:Hormones; D010906:Pituitary Hormone-Releasing Hormones; D007987:Gonadotropin-Releasing Hormone; D004958:Estradiol; D007986:Luteinizing Hormone