Antihistaminics H1 and H2 do not modify the human prolactin response to arginine infusion and insulin hypoglycemia

Healthy adult subjects of both sexes volunteered for our studies. Sixteen subjects (10 M + 6 F) underwent an arginine infusion test (25 g in 30 min) in basal conditions and following the administration of H₁ antagonists in 8 subjects (meclastine, 3 mg/day for 3 days p.o. plus 1 mg 1 h before the second test, or dexchlorpheniramine, 10 mg, infused i.v. from -30 to 60 min) or after repeated cimetidine administration in 8 subjects (1.0 g/day p.o. for 5 days plus 0.4 g 1 h before the second test). Similarly, fourteen subjects (9 M + 5 F) underwent an insulin hypoglycemia test (0.1 U/Kg b.w.) in basal conditions and following treatment with H₁ antagonists (7 subjects) or H₂ antagonists (7 subjects). Plasma PRL level were determined in duplicate by radioimmunoassay (Gala, Singhakowinta and Brennan 1975). Arginine elicited in all subjects a slight but significant PRL release which was not modified by either H₁ or H₂ antagonists. Similarly, insulin hypoglycemia elicited a clear PRL response, unaffected by either H₁ or H₂ antagonists.