Effects of chronic stress on adrenal morphology of rats

BACKGROUND: It is known that because stress affects the hypothalamic-pituitary-adrenal axis, normal adrenal morphology is disrupted. However, there is controversy regarding how the adrenal cortex zones respond to chronic stress. The objective of this study was to investigate the morphological modifications caused by chronic stress in different zones of the adrenal glands of rats. MATERIALS AND METHODS: Sixteen 10-week-old male Wistar rats were used. Rats were randomly assigned to two groups: control (n = 8) and stressed (n = 8). Stressed animals were exposed to stress stimuli by immobilization in a rigid cylinder for 2 h daily in the evening from the 10th to the 18th week of life. The adrenal glands were dissected, and their weight and volume were measured. In addition, the volumes of the adrenal medulla and cortex and each cortical zone (zona glomerulosa, zona fasciculata, and zona reticularis) were calculated and compared between control and stressed animals. Student's t-tests were used for mean comparisons. RESULTS: Stressed animals showed a 42.3% increase in adrenal weight and a 28.1% increase in adrenal volume compared with control animals. Cortical volume was 32% higher in stressed animals than in controls. The zona fasciculata of stressed animals was 108.9% higher than that of controls, and the zona reticularis of stressed animals was reduced by 24.9% compared to controls. CONCLUSIONS: Chronic stress induces general adrenal morphological modifications, significantly increasing zona fasciculata, resulting in cortical and organ enlargement.