Progestagen,androgen and oestrogen levels in plasma and ovarian follicular fluid during the oestrous cycle of the mare |
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| Institution: | 1. Ambulatorische und Geburtshilfliche Veterinärklinik, Giessen Federal Republic of Germany;2. Zentrum für Frauenheilkunde und Geburtshilfe, Giessen Federal Republic of Germany;3. Institut für Tierzucht und Haustiergenetik der Justus-Liebig-Universität, Giessen Federal Republic of Germany;1. College of Nanotechnology, King Mongkut’s Institute of Technology, Ladkrabang, Bangkok, 10520 Thailand;2. Nanotec-KMITL Center of Excellence on Nanoelectronic Devices, King Mongkut’s Institute of Technology Ladkrabang, Chalongkrong Rd., Ladkrabang, Bangkok 10520, Thailand;1. Department of Reproduction Management, Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany;2. RBB Rinderproduktion Berlin-Brandenburg GmbH, Besamungsstation Schmergow, Groß Kreutz (Havel), Germany;1. Center of Scientific Experiment, Beijing University of Chinese Medicine, 11 Beisanhuandong Road, Chaoyang District, Beijing 100029, China;2. School of Basic Medical Sciences, Beijing University of Chinese Medicine, 11 Beisanhuandong Road, Chaoyang District, Beijing 100029, China;3. School of Chinese Materia Medica, Beijing University of Chinese Medicine, 11 Beisanhuandong Road, Chaoyang District, Beijing 100029, China;4. The third affiliated hospital, Beijing University of Chinese Medicine, 11 Beisanhuandong Road, Chaoyang District, Beijing 100029, China;1. Departamento de Biología, Comisión de Genética, Universidad Autónoma de Madrid (UAM), C. Darwin 2, E-28049 Madrid, Spain;2. Centro de Investigación en Biodiversidad y Cambio Global (CIBC-UAM), Universidad Autónoma de Madrid, C. Darwin 2, E-28049 Madrid, Spain;3. Centro Militar de Cría Caballar de Ávila (FESCCR- Ministerio de Defensa), 05005 Ávila, Spain;4. Centro de Investigación sobre la Desertificación, CIDE-CSIC, Valencia, Spain;5. Department of Animal Reproduction & Artificial Insemination, Veterinary Research Division, National Research Center, 12622 Giza, Egypt;1. Department of Animal Medicine and Surgery, Faculty of Veterinary, Cardenal Herrera-CEU University, Valencia, Spain;2. Department of Veterinary Sciences, Veterinary Physiology Unit, Polo Universitario Annunziata, Messina University, Italy |
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| Abstract: | The pattern of steroid hormone concentrations in the blood plasma of five mares was determined throughout eight oestrous cycles by radioimmunoassay. In three other mares the steroid hormone concentrations in the follicular fluid of 16 isolated follicles (⪖ 1 cm diameter) from both ovaries were analyzed on the first and third day of behavioural oestrus.The plasma levels of pregnenolone and progesterone as well as their 17α-hydroxylated metabolites showed similar ranges of concentration throughout the oestrous cycle. Luteolysis occurred 6 days prior to ovulation and was accompanied by a drop of all progestagens. Throughout the oestrous period (5 days prior to and including the day of ovulation) mean plasma concentrations of progestagens were <0.5 ng/ml and increased significantly one day after ovulation. Maximum plateau values were reached on day 6 after ovulation. A distinct (but not statistically significant) rise of androstenedione and testosterone plasma levels occurred during oestrus whereas dehydroepiandrosterone values increased significantly 6 days prior to ovulation and reached a maximum mean value of 1.14 ng/ml one day before ovulation. Levels then declined significantly on the day of ovulation. Oestrone and oestradiol-17β plasma concentrations increased significantly 4 and 3 days prior to the day of ovulation, respectively, and both remained elevated until one day before ovulation.A significant positive correlation could be detected between increasing follicle diameters and androstenedione as well as oestradiol-17β concentrations in the follicular fluid, whereas pregnenolone values showed a negative correlation with follicular diameter. Oestradiol-17β could be determined in 9 of the 16 follicular fluid samples. In 8 of these 9, oestradiol-17β predominated over all other steroid hormones.In view of the low concentrations of dehydroepiandrosterone detected in the follicular fluid, it is suggested that the increase in peripheral plasma values during oestrus is caused by an extra-follicular source(s). |
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