The influence of estrogen on plasma prolactin levels induced by Thyrotrophin Releasing Hormone (TRH), clonidine and serotonin in ovariectomized rats
1977; Elsevier BV; Volume: 20; Issue: 2 Linguagem: Inglês
10.1016/0024-3205(77)90320-4
ISSN1879-0631
AutoresR. W. STEVENS, David M. Lawson,
Tópico(s)Menopause: Health Impacts and Treatments
ResumoProlactin levels were determined in the plasma of ovariectomized and ovariectomized estrogen treated rats by RIA following intraarterial injection of TRH, (1 and 10 μg/rat), clonidine (5 mg/kg) and serotonin (10 mg/kg). In ovariectomized rats, TRH had no effect on plasma prolactin whereas serotonin and clonidine induced slight and moderate increases respectively. In contrast, TRH induced a significant increase in plasma prolactin in estrogen-treated rats while the effects of the other two agents were enhanced only slightly (clonidine) or very markedly (serotonin). These results indicate that the prolactin-releasing activity of TRH is dependent on estrogen and that estrogen differentially affects noradrenergic and serotonergic components of the neuroendocrine mechanism that controls prolactin. It is also suggested that clonidine and serotonin probably do not increase plasma prolactin by releasing endogenous TRH.
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