Maintenance by L-DOPA treatment of estrous cycles and LH response to estrogen in aging female rats |
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| Authors: | L. J. Forman W. E. Sonntag N. Miki J. Meites |
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| Affiliation: | 1. Post-doctoral fellow of the National Institute on Aging, AG, 05208;2. Department of Physiology , Neuroendocrine Research Laboratory , Michigan State University, East Lansing, Michigan, 48824, U.S.A.;3. Post-doctoral fellow of the National Institute on Aging, AG, 05147;4. Department of Physiology , Neuroendocrine Research Laboratory , Michigan State University, East Lansing, Michigan, 48824, U.S.A.;5. Aided in part by NIH research grants AG00416 from the National Institute on Aging, and AM04784 from the National Institute on Arthritis, Metabolism and Digestive Diseases |
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| Abstract: | ![]()
Nineteen, non-cycling female rats, 13–15 months of age, were fed 125 mg L-DOPA/15 g feed daily, and nineteen control rats of the same age were provided feed without L-DOPA. Sixteen of the L-DOPA fed rats each demonstrated 1–7 (average = 3) vaginal estrous cycles during the 75-day period of treatment, whereas no cycles were observed in the untreated controls. All animals were then ovariectomized and the post-castration rise in LH was monitored. Four weeks after ovariectomy, serum LH levels in the L-DOPA treated old female rats were significantly higher than in the non-treated old female rats. A single injection of 20μg of estradiol benzoate (EB) significantly lowered serum LH in the L-DOPA treated rats, but no effect was observed in the non-treated controls. A second injection of EB three days later produced a significantly greater LH surge in the old rats given L-DOPA than in the non-L-DOPA treated controls. These results indicate that prolonged L-DOPA administration can partially prevent the decline in function of the hypothalamo-pituitary-ovarian system in aging female rats. |
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