Hyperprolactinemia Counteracts the Testosterone-Induced Inhibition of the Preoptic Area Dopamine Turnover
- 1 January 1981
- journal article
- research article
- Published by S. Karger AG in Neuroendocrinology
- Vol. 33 (2), 118-122
- https://doi.org/10.1159/000123214
Abstract
The present study was undertaken to determine the effects of hyperprolactinemia on dopamine (DA) concentrations and turnover rates in the medial basal hypothalamus (MBH) and the preoptic area-suprachiasmatic nucleus region (POA-SCN) in castrated and castrated, testosterone (T) implanted male rats. Subcutaneous implants, which raised serum T levels to those found in intact rats, decreased serum LH to basal levels but did not alter DA turnover in the MBH. Anterior pituitary (AP) transplants under the renal capsule increased serum prolactin to 60–110 ng/ml, and accelerated DA turnover by nearly 2-fold in the MBH of both castrated and castrated, T-implanted rats without influencing serum LH levels. While T implants caused a decrease in the POA-SCN DA turnover, high serum prolactin levels produced by AP implants in castrated rats were ineffective in altering POA-SCN DA turnover. However, in the presence of physiological levels of T, these elevated serum prolactin levels not only blocked the T-induced decrease in POA-SCN DA turnover, but further augmented DA turnover over that observed in the castrated or castrated, T-implanted rats. These results indicate that (i) for acceleration of the MBH DA turnover by prolactin T priming is not essential and it appears to occur at serum prolactin levels which do not depress serum LH levels, and (ii) the stimulatory effects of prolactin on the POA-SCN DA turnover are dependent upon the presence of circulating T. Since these synergistic effects of prolactin and T on the POA-SCN DA turnover are not involved in the regulation of gonadotropin secretion, their participation in attenuation of male sexual behavior associated with hyperprolactinemia is discussed.Keywords
This publication has 21 references indexed in Scilit:
- Circadian Periodicities of Serum Androgens, Progesterone, Gonadotropins and Luteinizing Hormone-Releasing Hormone in Male Rats: The Effects of Hypothalamic Deafferentation, Castration and Adrenalectomy1Endocrinology, 1977
- Effects of estrogen on prolactin and tuberoinfundibular dopaminergic neuronsJournal of Neural Transmission, 1977
- Prolactin-Like Immunoreactivity: Localization in Nerve Terminals of Rat HypothalamusScience, 1977
- Inhibition ofin VivoPituitary Release of Luteinizing Hormone in Lactating Rats by Exogenous ProlactinEndocrinology, 1977
- COMPARISON OF EFFECTS OF HALOPERIDOL ON DOPAMINE TURNOVER IN STRIATUM, OLFACTORY TUBERCLE AND MEDIAN-EMINENCE1977
- ANTIGONADOTROPHIC EFFECT OF PROLACTIN IN ADULT CASTRATED AND IN IMMATURE FEMALE RATSActa Endocrinologica, 1977
- Effects of Experimentally-Induced Chronic Hyperprolactinemia on Testosterone and Gonadotropin Levels in Male Rats and MiceEndocrinology, 1977
- Differential drug effects on dopamine concentrations and rates of turnover in the median eminence, olfactory tubercle and corpus striatumJournal of Neural Transmission, 1976
- Selective Actions of Prolactin on Catecholamine Turnover in the Hypothalamus and on Serum LH and FSHNeuroendocrinology, 1976
- APPLICATION OF STEADY STATE KINETICS TO ESTIMATION OF SYNTHESIS RATE AND TURNOVER TIME OF TISSUE CATECHOLAMINES1966