title: Maintenance by L-DOPA treatment of estrous cycles and LH response to estrogen in aging female rats.
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 20 micrograms 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.
mesh_terms: D000375:Aging; D000818:Animals; D002369:Castration; D004958:Estradiol / Q000494:pharmacology*; D004971:Estrus / Q000187:drug effects*; D005260:Female; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D007980:Levodopa / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000378:metabolism*; D010913:Pituitary-Adrenal System / Q000502:physiology; D011247:Pregnancy; D011388:Prolactin / Q000378:metabolism; D051381:Rats
chemical_list: D007980:Levodopa; D004958:Estradiol; D011388:Prolactin; D007986:Luteinizing Hormone