NITRIC-OXIDE PLAYS NO ROLE IN ACTH RELEASE INDUCED BY INTERLEUKIN-1-BETA CORTICOTROPIN-RELEASING HORMONE, ARGININE-VASOPRESSIN AND PHORBOL-MYRISTATE ACETATE IN RAT PITUITARY CELL-CULTURES

To investigate the role of nitric oxide (NO) in pituitary ACTH secretion,the effect of a nitric oxide synthase (NOS) inhibitor, N omega-Nitro-L-arginine (Nitro-Arg), on ACTH secretion induced by interleukin (IL)-1 beta, corticotropin releasing hormone (CRH), arginine vasopressin (AVP) and phorbol myristate acetate (PMA) was examined in rat anterior pituitary cell cultures. Nitro-Arg did not affect IL-1 beta-induced ACTH release in pituitary cell cutures incubated with Dulbecco modified Eagle's medium, Basal Medium Eagle or Krebs Ringer bicarbonate-glucose buffer. It did not affect CRH-, AVP- or PMA-induced ACTH release either. These results suggest that NO does not play an important role in ACTH release at the pituitary level.