The Effect of Stress on the Cytology and Immunocytochemistry of Pars Intermedia Cells in the Rat Pituitary

The purpose of this study was to determine if there were ultrastructural and immunocytochemical changes in intermediate lobe cells following stress. We found marked cytological changes in intermediate lobe cells after 30 min of stress with a buzzer and stroboscopic light (neurogenic). Following such treatment, the cytoplasm was filled with pale graules or empty vesicles. There was cytological evidence of increased secretory and synthetic activity. Innunocytochemical staining (for 17-39-ATCH) revelaed that there were fewer stained granules per cell in such rats although the individual granules stained as strongly as those in control rats. No cytological changes were observed following ether stress. These results correlated well with our bioassay and radioimmunoassay data which showed that only neurogenic stress resulted in depletion of ACTH from neuro-intermediate lobes (1). In agreement with the work of others, we found no obvious cytological changes in intermediate lobes from adrenalectomized or cortisol treated rats wheras anterior lobe ACTH cells hypertrophied following adrenalectomy and involuted following cortisol treatment. Anterior lobe ACTH cells from intact rats showed no degranulation following 30 min of buzzer stress or after 2 min of ether stress.