Effect of angiotensin II on the proliferation of mammotrophs from the adult rat anterior pituitary in culture.

We measured the influence of prolactin-releasing neuropeptides on mammotroph proliferation in cultures of rat adenohypophysis cells using flow cytometry. Angiotensin II (AII) increased mammotroph proliferation. Other peptides with hormone-releasing activities did not promote growth. Tamoxifen inhibited mammotroph proliferation in control and AII-containing cultures and the inhibition was reversed with beta-estradiol. Saralasin, an AII receptor antagonist, suppressed not only AII-induced mammotroph proliferation but also luteinizing hormone-releasing hormone (LHRH)-induced proliferation. These results suggest that hypothalamic LHRH stimulates AII release from gonadotrophs and that AII, with estrogen, controls mammotroph proliferation in rat pituitary.