Resumen de Effects of Arg-vasopressin and corticosterone on IL-1ß-induced modifications of pituitary ACTH-producing cells.

Julio Herrero Payo, Ricardo Vázquez, Enrique J. Blanco Barco, José Manuel Riesco Santos, José Carretero González, M. Carretero, M. M. Montero, Manuel Rubio Sánchez, R. González

• Interleukin 1b (IL-1b) stimulates the hypothalamic- pituitary-adrenal axis, however the autoparacrine effects of IL-1b¿ on pituitary ACTHproducing cells and the relations among IL-1b and Arg-vasopressin or corticosterone have not yet been analyzed. To address these effects, pituitary monolayer cultures were treated with IL-1b, Arg-vasopressin and corticosterone, either alone or in combined treatment, and an immunocytochemical, morphometric and densitometric study of ACTH-positive cells was carried out. IL-1b significantly increased the percentage and cellular and nuclear size of ACTH-positive cells, and similar effects were found following treatment with Arg-vasopressin. Combined treatment with IL-1b and Arg-vasopressin increased these parameters more than in separate treatments. Corticosterone decreased these parameters and blocked the effects of IL-1b and Arg-vasopressin in the combined treatments. In sum, our results suggest that IL-1b is an auto-paracrine regulator of pituitary ACTH-producing cells, that it reinforces the stimulatory effects of Arg-vasopressin and that corticosterone is an inhibitory regulator of the auto-paracrine effects of IL-1b and Argvasopressin.