Role of Adrenal Progenitor Cells in the Structural Response of Adrenal Gland to Various forms of Acute Stress and Subsequent Recovery in Adult Male Albino Rats.

Background: Stress is a response to stressogenic stimuli that interferes with an organism's homeostasis. The adrenal gland is crucial in the body's reaction to stress. Objective: This study compared the effects of immobility and cold as acute stressors and the subsequent recovery on the histological changes of the adrenal gland and the suspected role of the adrenal progenitor cells. Materials and Methods: Thirty-five adult male albino rats were divided equally into five groups. Group I: Control group, Group II: Rats subjected to the acute cold stress procedure, Group III: Rats subjected to the acute immobilization stress procedure, Group IV: The combined stress group, and Group V: Similar to the combined stress group and recovered for 6 days then sacrificed 1 day later. Serum cortisol level was determined, and the adrenal glands were processed for histological and immunohistochemical studies. Results: Serum cortisol concentration was higher in the acute-stress groups and decreased in the recovery group. The adrenal cortex had enlarged, vacuolated cells with pyknotic nuclei, sinusoidal dilatation, and congestion. Chromaffin cells were crowded, enlarged, and vacuolated. There was strong immunohistochemical reactivity for heat shock protein-70 and caspase-3. In addition, the combined group showed a significant increase in the optical density of chromogranin-A in the medullary cells as well as CD44+ve cells. These findings were decreased in the recovery group. Conclusions: The combined stress has more deleterious adrenal cortical changes than immobilization and cold stress alone. The progenitor and chromaffin cells apparently had an important regenerative role in recovery from both types of stress.