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THE INFLUENCE OF OESTROGENS ON THE SENSITIVITY OF PRL, TSH AND LH TO THE INHIBITORY ACTIONS OF DOPAMINE IN HYPERPROLACTINAEMIC PATIENTS
Author(s) -
VALCAVI R.,
HARRIS P. E.,
FOORD S. M.,
DIEGUEZ C.,
EVANS P. J.,
PETERS J. R.,
HALL R.,
SCANLON M. F.
Publication year - 1985
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1985.tb00208.x
Subject(s) - medicine , endocrinology , basal (medicine) , prolactin , hyperprolactinaemia , dopamine , chemistry , hormone , insulin
SUMMARY The effects of oestrogen priming on the response of serum PRL, LH and TSH to dopamine (DA) infusion have been studied in hyperprolactinaemia. Seven hyperprolactinaemic females (aged 22–57 years; basal PRL 911–5130 mU/1, normal >420 mU/1), had submaximal DA infusions (0·06 μg/kg/min) over 3 h. The DA was repeated at the same dose after pretreatment with ethinyl oestradiol (E 2 ) 100 μg daily by mouth for 3 d, and after a further 2 week interval, following pretreatment with tamoxifen (TAM) 20 mg twice a day by mouth for 3 d. Ethinyl oestradiol pretreatment stimulated a rise in basal PRL levels in all subjects (mean ± SE, mU/1; 2903 ± 761 vs 2293 ± 684, P >0·05) while TAM produced a higher but more variable increase in basal PRL levels (mean ± SE, mU/1; 3402 ± 757, P = n.s.). The individual increments in basal PRL levels after both E 2 and TAM pretreatment showed a significant positive correlation with the greater decrement in PRL levels during E 2 and TAM primed DA infusions (E 2 , r = 0·93, P > 0·01, TAM, r = 0·83, P > 0·05). E 2 pretreatment produced a rise in basal LH levels in 5/7 patients, and there was a significant positive correlation between the rise in basal LH levels after E 2 and the decremental change in LH levels in E 2 primed DA infusions ( r = 0·94, P >0·01). Basal TSH levels were unaffected by E 2 and TAM pretreatment, but during DA infusion there was a significantly greater decremental change following E 2 pretreatment (sum of decrements, mean ± SE mU/1; 8·1 ± 1·58 vs 4·65 ± 1·23, P > 0·02). In conclusion, E 2 and TAM increased PRL sensitivity to the inhibitory actions of DA treatment. In contrast, E 2 but not TAM, exerted similar effects on the dopaminergic inhibition of LH and TSH.