title: Aging influences steroid hormone release by mink ovaries and their response to leptin and IGF-I.
abstract: The aim of our study was to understand whether ovarian steroid hormones, and their response to the metabolic hormones leptin and IGF-I leptin, could be involved in the control of mink reproductive aging via changes in basal release of ovarian progesterone and estradiol. For this purpose, we compared the release of progesterone and estradiol by ovarian fragments isolated from young (yearlings) and old (3-5 years of age) minks cultured with and without leptin and IGF-I (0, 1, 10 or 100 ng/ml). We observed that isolated ovaries of older animals produced less progesterone but not less estradiol than the ovaries of young animals. Leptin addition stimulated estradiol release by the ovarian tissue of young animals but inhibited it in older females. Leptin did not influence progesterone output by the ovaries of either young or older animals. IGF-I inhibited estradiol output in young but not old animals, whereas progesterone release was inhibited by IGF-I irrespective of the animal age. Our observations demonstrate the involvement of both leptin and IGF-I in the control of mink ovarian steroid hormones release. Furthermore, our findings suggest that reproductive aging in minks can be due to (a) reduction in basal progesterone release and (b) alterations in the response of estradiol but not of progesterone to leptin and IGF-I.
authors.affiliation: Department of Zoology and Anthropology, Constantine the Philosopher University, Nitra 949 74, Slovakia Department of Genetics and Reproduction, Research Institute of Animal Production, Lužianky 949 59, Slovakia sirotkin@vuzv.sk asirotkin@ukf.sk.
authors.forename: Alexander V
authors.initials: AV
authors.lastname: Sirotkin
authors.affiliation: Department of Genetics and Reproduction, Research Institute of Animal Production, Lužianky 949 59, Slovakia.
authors.forename: Dušan
authors.initials: D
authors.lastname: Mertin
authors.affiliation: Department of Genetics and Reproduction, Research Institute of Animal Production, Lužianky 949 59, Slovakia.
authors.forename: Karin
authors.initials: K
authors.lastname: Süvegová
authors.affiliation: Department of Zoology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
authors.forename: Abdel Halim
authors.initials: AH
authors.lastname: Harrath
authors.affiliation: Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn 10-747, Poland.
authors.forename: Jan
authors.initials: J
authors.lastname: Kotwica
keywords: Aging; Estradiol; IGF-I; Leptin; Mink; Ovary; Progesterone