Abstract

Prolactin, as a "broad spectrum hormone", has been described to exert also vascular and renal actions in laboratory animals and in humans. However, prolactin preparations of various species are contaminated with neurohypophysial hormones (ADH, oxytocin) which possess vascular and renal activities. Antisera against ADH, oxytocin and prolactin are rather specific inactivators of the biologic activity of the respective hormone; the oxytocinasevasopressinase system of pregnancy plasma destroys ADH and oxytocin. Incubation-identification procedures with antisera against ADH, oxytocin and prolactin and with pregnancy plasma revealed that changes in blood pressure, urine flow and urinary osmolarity cannot be ascribed to prolactin per se but to the ADH impurity of prolactin preparations. Furthermore, recent metabolic studies in normally hydrated, overhydrate and dehydrated animals and humans have shown that prolactin does not affect renal water and electrolyte excretion. Thus, earlier reports on vascular and renal activity of prolactin in laboratory animals and humans should be viewed with great caution. Elimination of neurohypophysial hormone impurities of prolactin preparations by incubation with either ADH and oxytocin antisera or with pregnancy plasma provides techniques for better assessment of the real biologic effects of the prolactin molecule.