Resumen de Auto-paracrine regulation of the proliferation of pituitary ACTH-producing cells demonstrated by immunoblockade of IL-1ß

José Carretero González, M. Carmen Montero, G. Vázquez, Enrique J. Blanco Barco, Manuel Rubio Sánchez, José Manuel Riesco Santos, Julio Herrero Payo, Marta Carretero Trillo, E. Pérez, Ricardo Vázquez

• IL-1â is an interleukin synthesised in the pituitary gland and is involved in the stimulation of ACTH secretion. However, to date it has not been determined whether IL-1â is able to regulate the proliferation of pituitary ACTH-producing cells, like other regulatory factors involved in the regulation of ACTH such as vasopressin or CRH. The aim of the present study was to address whether IL-1â is involved in regulating the proliferation and apoptosis of pituitary ACTH-secreting cells. Thus, we performed an in vitro study on monolayer cultures of rat pituitary cells, neutralising the possible paracrine effect of IL-1â by immunoblockade of the interleukin and later determining the degree of proliferation or apoptosis of ACTH-secreting cells. The effects of immunoblockade were validated by determining the modifications in the patterns of the immunohistochemical reaction to ACTH-positive cells. Immunoblockade of IL- 1â decreased the percentage and proliferation of ACTH-positive cells at all time-points analysed, mainly between 6 and 12 h (p<0.01). Moreover, immunoblockade decreased the sizes of the cellular and nuclear areas at all time-points studied, with significant decreases (p<0.01) after 3, 6 and 12 hours. The results obtained suggest that -in the same way as it regulates the secretion of the hormone- IL-1â could be involved in regulating the proliferation of ACTH cells.