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Nihon Juigaku Zasshi

Title:		Melatonin but not the ram-effect reactivates quiescent ovarian activity of mid-anestrous ewe
Author(s):		Mori Y; Shimizu K; Hoshino K;
Address:		"Laboratory of Veterinary Reproduction, Tokyo University of Agriculture and Technology, Japan"
Journal Title:		Nihon Juigaku Zasshi
Year:		1990
Volume:		52
Issue:		4
Page Number:		773 - 779
DOI:		10.1292/jvms1939.52.773
ISSN/ISBN:		0021-5295 (Print) 0021-5295 (Linking)
Abstract:		"The present study was conducted to examine how the social cue emanating from rams, the ram-effect, would influence the onset of melatonin-induced reproductive activity in anestrous ewes. Twenty non-lactating ewes were randomly allocated into 4 groups as follows based on a combination of the melatonin treatment (MEL) and the ram-effect (RAM): ewes of Groups A (MEL + RAM) and B (MEL) were subcutaneously implanted with melatonin capsules on April 18 (Day 0), which increased plasma melatonin levels by about 200 pg/ml for at least 5 months, while Groups C (RAM) and D (control) were untreated with melatonin. Rams were introduced to Groups A and C on Day 0, whereas Groups B and D were isolated from rams. Ovarian function of the ewe was assessed on June 9-21 (Days 52-64) by monitoring plasma progesterone (P) profiles. Luteal function (plasma P greater than 1 ng/ml for a week or longer) was evident in all the melatonin-treated ewes but only one in those untreated: 5/5 in Group A, 5/5 in Group B, 1/5 in Group C and 0/5 in Group D. By ultrasonography on Day 105 all the Group A ewes were diagnosed pregnant but none in the Group C despite that both the two groups had been run with rams. These results indicate that chronic melatonin treatment is capable of advancing the reproductive recrudescence in seasonally anestrous ewes, and that progonadal effects of rams are subtle, if any, during the mid-anestrous period"
Keywords:		Anestrus/*drug effects Animals Estrus/*drug effects Female Melatonin/blood/*pharmacology Ovary/*drug effects Ovulation Induction/veterinary Periodicity Pheromones/*physiology Pregnancy Progesterone/blood Prolactin/blood Radioimmunoassay/veterinary Random;
Notes:		"MedlineMori, Y Shimizu, K Hoshino, K eng Research Support, Non-U.S. Gov't Japan 1990/08/01 Nihon Juigaku Zasshi. 1990 Aug; 52(4):773-9. doi: 10.1292/jvms1939.52.773"