Daily melatonin injections: Their usefulness in understanding photoperiodism inPeromyscus leucopus
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To determine the effects of long-term melatonin injections on reproduction and the seasonal molt inPeromyscus leucopus, 60 female mice were injected subcutaneously 12h after “lights on” with either 50 μg of melatonin (in saline) or saline each day for 7, 12, or 18 wk. Reproductive regression was apparent in the 7 and 12 wk groups from a decreased reproductive tract weight, absence of preovulatory follicles in the ovaries, and presence of an imperforate vagina. Spontaneous recrudesence occurred by 18 wk. Molt to the winter pelt occurred in the 12 and 18 wk melatonin groups. All saline-injected mice remained reproductively competent and none molted.
KeywordsPlant Physiology Melatonin Female Mouse Reproductive Tract Environmental Medicine
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