This study was conducted to investigate the effect of vaccinating mares against melatonin on seasonal reproductive cycles. Melatonin-Bovine serum albumin (Mel-BSA) conjugate, mixed with a Quil A based adjuvant was utilized to immunize the mares during the anestrous season of two consecutive years (November, 1997–May, 1998, and November, 1998–May, 1999). In year 1, mares were vaccinated 4 times beginning in November at 1 week, 3 week and 3 week intervals with low antigen dose (0.25, 0.5, 0.5, 0.5 mg Mel-BSA per mare, n = 7), high antigen dose (2.5, 5.0, 5.0, and 5.0 mg Mel-BSA per mare, n = 6), control (0.25, 0.5, 0.5, 0.5 mg BSA per mare, n = 4) or none (no injection, n = 1). In year 2, mares were re-vaccinated 3 times beginning in November at 3 week, 3 week and 4 week intervals with 0.5 mg of Mel-BSA (n = 11) or BSA alone (n = 6). The seasonal reproductive cycles were evaluated by measuring serum progesterone concentration with ELISA and by following the ovarian activity using transrectal ultrasonography. In Year 1, the progesterone production patterns, percentage of cycling mares, the winter anestrous length, and the beginning of vernal transition (BVT) were similar between the treatment and control groups. However, in year 2 the progesterone production patterns in the treatment group was altered; 2 mares out of 11 were cycling throughout the winter and the percentage of cycling mares in the treatment group increased compared with the control; there was significant difference between the treatment and control groups in winter anestrous length (p < 0.05) and in BVT (p < 0.05) Anti-melatonin antibodies could directly neutralize circulating melatonin and block melatonin binding to its receptors on equine lymphocyte cell membrane (Kd = 172.9 ± 10.8 pM) and on equine pineal gland cell membrane (Kd = 139.2 ± 11.2 pM) in vitro. The results of this study demonstrated that vaccinating mares against melatonin could after the seasonal reproductive cycle, and the mechanisms underlying this effect likely include neutralization of circulating melatonin and the blockade of melatonin binding to its receptors by specific antibodies.
| Identifer | oai:union.ndltd.org:UMASS/oai:scholarworks.umass.edu:dissertations-3487 |
| Date | 01 January 2001 |
| Creators | Zheng, Shi-Jun |
| Publisher | ScholarWorks@UMass Amherst |
| Source Sets | University of Massachusetts, Amherst |
| Language | English |
| Detected Language | English |
| Type | text |
| Source | Doctoral Dissertations Available from Proquest |
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