Serum prolactin concentrations in mangabey (Cercocebus atys lunulatus) and patas (Erythrocebus patas) monkeys in response to stress, ketamine, TRH, sulpiride and levodopa

Abstract

An homologous radioimmunoassay for human serum prolactin was validated to measure serum prolactin in 10 mangabey and 7 patas monkeys. Mean basal levels of serum prolactin were almost identical in the males of both species and in immature and mature males. Basal levels were higher in females than in males. Serum prolactin was enhanced by stress, i.v. injection of TRH [thyrotropin releasing hormone] and i.m. injection of a potent dopamine antagonist (sulpiride). The rise in serum prolactin observed after i.m. injection of ketamine hydrochloride used as anesthetic was of small amplitude and short duration. Oral administration of L-dopa was followed by a significant fall in serum prolactin. Sexual maturity did not influence the responses to TRH or sulpiride. The mangabeys were more sensitive to sulpiride but less sensitive to L-dopa than were the patas monkeys. The variations in serum prolactin levels observed in these monkeys under the influence of stress, TRH, sulpiride and L-dopa are similar to those observed in man to the same stimuli, although the experimental conditions were quite different.