The influence of gonadal steroids on the dopamine inhibitory effect on gonadotropin release in men.
The aim of this study was to ascertain whether an interrelationship exists between gonadal steroids and the inhibition of gonadotropin secretion by dopamine. The effect of dopamine infusion (4 micrograms/kg/minute intravenously) on gonadotropin plasma levels in four castrated men (18 to 23 years of age) and in four age-matched normal men was studied. Normal subjects were studied before and after treatment with a specific nonsteroidal estrogen receptor antagonist, CC. LH plasma levels in normal subjects receiving CC had a maximum decrease percentage and a net decrease significantly greater (P less than 0.005 and P less than 0.012, respectively) than those before CC treatment. In castrated subjects the maximum decrease percentage was significantly greater (P less than 0.005) than in control subjects, but it did not show any difference from that of normal subjects receiving CC. In none of the group were significant changes in FSH concentration observed. The findings suggest that whenever there is a gonadal steroid deficiency, dopamine infusion causes an increased sensitivity to LH inhibition. This may be due to a lower endogenous dopaminergic influence on LH secretion.
D000293:Adolescent; D000328:Adult; D000728:Androgens / Q000502:physiology; D002369:Castration; D002996:Clomiphene / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology*; D004965:Estrogen Antagonists; D004967:Estrogens / Q000502:physiology; D005640:Follicle Stimulating Hormone / Q000097:blood / Q000378:metabolism*; D012739:Gonadal Steroid Hormones / Q000502:physiology*; D006801:Humans; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D008297:Male; D011863:Radioimmunoassay
D000728:Androgens; D004965:Estrogen Antagonists; D004967:Estrogens; D012739:Gonadal Steroid Hormones; D002996:Clomiphene; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D004298:Dopamine