Enhancement of estradiol-induced DNA synthesis in the anterior pituitary gland by the peripheral-type benzodiazepine receptor ligand Ro 5-4864.

The effects of peripheral (Ro 5-4864) and central-type (Ro 15-1788) benzodiazepine receptor ligands on estrogen-induced DNA synthesis in the rat anterior pituitary gland was investigated. As expected, a single injection of estradiol (250 micrograms per rat) significantly increased the uptake of 3H-thymidine by anterior pituitary cells. Additional treatment with Ro 5-4864 potentiated the effects of estradiol on pituitary DNA synthesis. Under the same experimental conditions, no effect of Ro 15-1788 and sodium valproate, a GABA-transaminase inhibitor, was detected. These findings indicate the involvement of peripheral-type benzodiazepine receptors in the control of anterior pituitary cell proliferation.