Effect of Chronic Unpredictable Mild Stress on Adrenal Cortex of Adult Rat and The Possible Protective Role of Licorice Extract: A Histological and Immunohistochemical study

Abstract

Background: Chronic stress, evolving due to sudden unexpected life events, is a risk factor for the development of depression. It can suppress immunity and increase susceptibility to inflammatory diseases. Licorice extract is commonly used in traditional and modern medicine particularly for its antioxidant and anti-inflammatory properties. Aim of the work: This work aimed to perform a biochemical, histological, and immunohistochemical assessment of the influence of chronic unpredictable mild stress (CUMS) on the structure of the adrenal cortex of rat and the possible ameliorating role of licorice aqueous extract. Material and Methods: Twenty-four adult male albino rats were divided into 4 groups; control, licorice, CUMS (exposed to variable stressors in a random unpredictable pattern for 4 weeks), and licorice & CUMS (same as group III along with 300 mg/kg/day of licorice extract). Plasma aldosterone and corticosterone were assayed. Adrenal cortex specimens were processed for biochemical, histological, and immunohistochemical studies. Results: CUMS group recorded a significant elevation of plasma aldosterone, corticosterone, tissue malondialdehyde and myeloperoxidase associating with a significant reduction of tissue reduced glutathione and superoxide dismutase. Histological examination revealed adrenal capsular thickening and subcapsular hyperplasia, disruption of the architecture and thickness of all zones, and cellular alterations as nuclear abnormalities and cytoplasmic vacuolation. A significant upregulation in both activated caspase-3 and PCNA immunohistochemical expression was recorded. Licorice co-treated group depicted near normal values of most parameters with a near control morphology. Conclusion: Licorice could prove beneficial in controlling the adverse effects exerted by CUMS on redox status, morphology, apoptosis, and proliferation of the adrenal cortex most probably through its antioxidant, anti-inflammatory, and antiproliferative properties.