The effects of an antihistamine and/or a glucocorticoid on the prolactin response to surgical procedures.

Prolactin (PRL) release in response to surgical stress has been demonstrated in a variety of species. Previous studies in rats indicate this response is blunted or blocked by pretreatment with either glucocorticoids or antihistamines. The present study was designed to investigate this phenomenon in man. Serum PRL levels before, during, and after major gynecologic surgery were measured in 20 women randomly assigned to one of four pretreatment regimens: (1) dexamethasone, (2) promethazine, (3) both agents, and (4) neither agent. Type of operation, preanesthetic medication, anesthetic agents, and estrogen status of patients were similar in all groups. Untreated controls exhibited the expected five- to tenfold increase in serum PRL concentration with surgery. Pretreatment with either dexamethasone or promethazine alone failed to suppress this response (in contrast to reported findings in the rat) and in fact promethazine appeared to cause an augmented response. However, patients given dexamethasone and promethazine together exhibited only a two- to threefold PRL increase, a significantly lesser response than that in any of the other groups. Thus, PRL release in response to general anesthesia and surgery is inhibited by the combination of an antihistamine (H-l) receptor antagonist and a glucocorticoid, whereas either agent alone has no suppressive effect.