Abstract
Dopamine (DA) has been shown by previous investigators to inhibit gonadotropin secretion in man. The purpose of our study was to determine the mechanism (s) by which this inhibition occurs. DA, its antagonist haloperidol (HA), and gonadotropin-releasing hormone (GnRH) were used as investigative agents. Conclusions are based on changes in LH pulse frequency and amplitude, as well as mean gonadotropin response and response areas during various treatments. Five normal men (23–30 yr of age) received 4-h constant iv infusions of saline (0), DA (4 µg/kg/min), synthetic GnRH (0.4 µg/min), DA (4 µg/tg/kg/min) plus GnRH (0.4 µg/min), and HA (2.5 mg, orally). Blood was sampled via an indwelling cannula from the opposite arm every 15 min for 1 h before, during, and after the infusion or HA treatment. The LH and FSH concentrations were measured in each sample by RIA. Testosterone was also measured but only in samples at hourly intervals. The maximum LH concentrations during the 0, DA, GnRH, DA plus GnRH, and HA treat...
Published Version
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