Eur J Anat, 10 (1): 7-13 (2006)

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

Carretero J., Montero M.C., Vazquez G., Blanco E., Rubio M., Riesco-Lopez J.M., Herrero J.J., Carretero M., Riesco J.M., Perez E., Vazquez R.

Departamento de Anatomía e Histología Humanas, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Spain; Departamento de Cirugía, Facultad de Medicina, Universidad de Salamanca, Spain; Departamento de Informática, Escuela de Educación, Universidad Pontificia de Salamanca, Spain; Departamento de Anatomía e Histología Humanas, Facultad de Medicina, Avda. Alfonso X el Sabio, s/n, E-37007 Salamanca, Spain

ABSTRACT IL-1? 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-1? 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-1? 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-1? 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-1? 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-1? could be involved in regulating the proliferation of ACTH cells.

Keywords: corticotropin, cycline, interleukin 1beta, animal cell, animal experiment, animal tissue, apoptosis, article, cell culture, cell proliferation, cell size, controlled study, corticotropin release, hormone release, hypophysis, hypophysis cell, immunohistochemistry, in vitro study, male, nonhuman, paracrine signaling, rat