The role of histamine in anterior pituitary secretion

Abstract

Objectives: The aim of the present study was to determine the effects of histamine on the anterior pituitary secretion in rats. Materials and Methods: In the first experiments rats were injected with histamine 5 mg/kg i.p., and blood samples were collected to determine the effect of histamine on serum level of adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), prolactin, FSH, and luteinizing hormone (LH) after 10, 20, and 30 min of histamine injection. In the second experiments, rats were treated with (H 1 blocker), chlorphenramine 10 mg/kg, i.p. or (H 2 blocker), cimetidine 80 mg/kg, i.p. respectively, and after 30 min they were injected with histamine and blood samples were taken 30 min after the injection of histamine to determine the same hormones. Results: Histamine significantly elevated serum ACTH and LH level, and these stimulatory effects were inhibited by both H1 and H2 receptor blockers. However, histamine significantly inhibited the serum level of thyroid-stimulating hormone and this inhibitory effect was blocked by H2 receptor blocker, while it showed no effect on the secretion of both prolactin and FSH, although H2 blocker significantly decreased prolactin level and H1 blocker significantly elevated FSH level. Conclusion: The results clearly indicated that histaminergic pathways were involved in the anterior pituitary secretion.