The behavior of adrenal progenitor stem cells in response to chronic stress and recovery

Stressors affect the differentiation of stem cells in the hypothalamic-pituitary-adrenal axis (HPA). This study was designed to ensure the presence of progenitor cells in the adult adrenal gland and to evaluate their behavior under chronic stress and after recovery. Also, to assess their ability to recruit new glial and chromaffin cells. Three groups of adult male rats (6 rats each): control, chronic-stress (rats were placed individually in stainless restrainers 2h/day for six days), recovered (rats were housed in an enriched circumference for seven days after the same stress modality). Both chronic-stress and recovered groups showed increased adrenal glands weight and cortisol levels with vacuolation, hemorrhage, and edema in the cortex and medulla. The chronic-stress group illustrated a significant increase in the chromaffin reaction, which was reduced in the recovered group. Evaluation of the immunohistochemical results revealed a significant decrease in the Nestin and GFAP (glial fibrillary acidic protein) reactions, but an increase in the chromogranin-A reaction in the chronic-stress group. The recovered group demonstrated a significant increase in the Nestin and GFAP and a reduction in the chromogranin-A immunohistochemical reactions. These results indicate the differentiation of the progenitor (Nestin expressing) stem cells into chromaffin (chromogranin-A expressing) cells under stress conditions for stress adaptation. Conversely, under normal conditions, the differentiation moved toward the glial cells.