Effect of intracerebroventricular injection of prostaglandin E2 on anterior pituitary cell proliferation.

The influence of an intracerebroventricular (i.c.v.) injection of prostaglandin E2 (PGE2) on the mitotic activity of the rat anterior pituitary was investigated. It was found that i.c.v. PGE2 (3 micrograms/20 microliters) resulted in a significant decrease of the mitotic activity in the anterior pituitary. This drop involved mainly chromophobic cells. No mitoses were found in acidophilic cells either in controls or in PGE2-treated rats. It is suggested that PGE2 may release an unidentified hypothalamic factor which inhibits the cell proliferation of the anterior pituitary.