[Immunohistochemical characteristics of the hypophysis under normal and stress-associated conditions]

Quantitative immunohistochemical investigation was undertaken to detect the peculiarities of the activation of the hypothalamic-hypophyseal-adrenocortical system at the level of its central unit--the adenohypophysis--in the growing organism under the conditions of chronic exposure to psycho-emotional stressors of varying intensities. Sprague-Dawley rats aged 30 days were exposed to either mild or severe chronic restraint stress for 5 hours during seven consecutive days. After the last exposure to stress, rats were decapitated, the endocrine glands (pituitary and adrenal glands) were removed, weighted, and embedded in paraffin; histological sections were stained with hematoxylin and eosin. Sections of hypophysis were also stained immunohistochemically using the monoclonal antibodies against adrenocorticotropic hormone (ACTH) and proliferating cell nuclear antigen (PCNA) with subsequent image analysis. The results of the study suggest that the stress-related hyperplasia of corticotropocytes in the hypophyseal pars distalis of the peripuberal rats was mainly associated with differentiation of the immature precursor cells of the hypophysis rather than with the increased cell proliferation.