Antidepressant-like effects of Ashwagandha (Withania Somnifera) on chronic unpredictable mild stress-induced depression in adolescent rats

Abstract

Rationale: Adolescent depression is often linked to biological changes associated with stress. However, new approaches and treatment strategies for early intervention and prevention of depression in children and adolescents are still limited. Ashwagandha is an Ayurvedic herb widely used in the management of anxiety and stress. However, there is no information in the current literature on its potential effect on adolescent depression.

Objectives: This study aimed to investigate the effects of depression on proapoptotic proteins and neuroinflammation and the antidepressant effect of Ashwagandha on depression-like symptoms in adolescent rats exposed to the Chronic Unpredictable Mild Stress (CUMS) model.

Methods: In the study, CUMS model was used to induce depression in adolescent rats. Rats were treated with Ashwagandha or Sertraline. To evaluate the antidepressant effects, behavioral tests as well as biochemical and histological analyses were performed. Forced Swim Test (FST), Sucrose Test and Elevated Plus Maze Test were performed as behavioral tests. Brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) were measured by the ELISA method in the fronto-parietal cortex. Proapoptotic proteins (Bax and Caspase-3) and inflammatory markers (TNF-α and IL-1β), as well as glial fibrillary acidic protein (GFAP), were evaluated immunohistochemically in the fronto-parietal cortex.

Results: Proapoptotic proteins (Bax and Caspase-3) and inflammatory markers (TNF-α and IL-1β) were increased in the CUMS group. BDNF and GFAP levels were decreased. Ashwagandha treatment was more effective than Sertraline in reducing the levels of these proteins and markers. Additionally, Ashwagandha prevented weight loss.

Conclusions: Ashwagandha showed antidepressant-like effects in adolescent rats, reducing apoptosis, inflammation, and neuroinflammation, suggesting potential for treating adolescent depression.

Keywords: Adolescent depression; Ashwagandha; CUMS; GFAP; Proapoptotic proteins; Sertraline.

Fig. 1

(a–c) SPT parameters: water consumption, sucrose solution consumption, and sucrose consumption percentage. (d–f) Elevated Plus Maze parameters: time spent in closed arms, time spent in open arms, and anxiety index. (g–h) FST parameters: time spent swimming and time spent inactive. Each bar with vertical line represents mean ± S.D. of 7 rats per group. Statistical significance was determined using one-way ANOVA followed by Tukey’s multiple comparison test. Significance is indicated as follows:*P < 0.05 vs. CONTROL, #P < 0.05 vs. CUMS. SPT: Sucrose Preference Test; FST: Forced Swimming Test; CUMS: Chronic Unpredictable Mild Stress induced rats; CUMS + SERT: Chronic Unpredictable Mild Stress was treated with Sertraline; CUMS + ASHW: Chronic Unpredictable Mild Stress was treated with Ashwagandha

Fig. 2

Histopathological micrographs of the fronto-parietal cortex and white mater in Control, CUMS, CUMS + SERT and CUMS + ASHW groups. Cortical neurons (arrow), and glial cells (curved arrow) with pyknotic nuclei. Existence of increased pericellular cavity due to presence of edema in white mater glial cells (curved arrow). The increased perivascular cavity (arrowhead) and accumulation of edema in stratum moleculare (asterisk) which is the most upper layer of the fronto-parietal cortex. The observed pathological changes are partially alleviated in CUMS + SERT group but the edema was still obvious in perivascular cavity (arrowhead). The neuronal and glial cell morphology and edema in cortex and white mater vessels (thick arrow) is remarkably reduced in CUMS + ASHW group. CUMS: Chronic Unpredictable Mild Stress induced rats; CUMS + SERT: Chronic Unpredictable Mild Stress was treated with Sertraline; CUMS + ASHW: Chronic Unpredictable Mild Stress was treated with Ashwagandha

Fig. 3

Histopathological micrographs of the fronto-parietalcortex and white mater in Control, CUMS, CUMS + SERT and CUMS + ASHW groups. Cortical neurons (arrow),and glial cells (curved arrow) with pyknotic nuclei. Existence of increased pericellular cavity due to presence of edema in white mater glial cells (curved arrow). The increased perivascular cavity (arrowhead) and accumulation of edema in stratum moleculare (asterisk) which is the most upper layer of the fronto-parietal cortex. The observed pathological changes are partially alleviated in CUMS + SERT group but the edema was still obvious in perivascular cavity (arrowhead). The neuronal and glial cell morphology and edema in cortex and white mater vessels (thick arrow) is remarkably reduced in CUMS + ASHW group.CUMS: Chronic Unpredictable Mild Stress induced rats; CUMS+SERT: Chronic Unpredictable Mild Stress was treated with Sertraline; CUMS+ASHW: Chronic Unpredictable Mild Stress was treated with Ashwagandha

Fig. 4

Demonstrative immunohistochemistry micrographs of the Bax, Caspase 3, TNF-α and IL-1β in Control, CUMS, CUMS + SERT and CUMS + ASHW groups. Existence of the brown color indicate immunopositivity of the interest protein. The samples are counterstaind to determine the immunodensity in each group. Counterstain: Hematoxylin. Bar: 100 µm.Representative micrographs of the GFAP immunohistochemistry in Control, CUMS, CUMS + SERT, CUMS + ASHW groups. Regular immunopositivity in astrocytes in control group (arrow). The immunodensity (curved arrow) and distribution of the immunpositive cells (arrow head) ratio is significantly reduced in CUMS group. The GFAP positive cells (thick arrow) in CUMS + SERT and the CUMS + ASHW groups. Counterstain: Hematoxylin. Bar: 50 µm. a: Bax, b: Caspase-3, c: TNF-α, d: IL-1β, e: GFAP. Each bar with vertical line represents mean ± S.D. of 7 rats per group. Statistical significance was determined using one-way ANOVA followed by Tukey’s multiple comparison test. Significance is indicated as follows: *P < 0.05 vs. CONTROL, #P < 0.05 vs. CUMS. CUMS: Chronic Unpredictable Mild Stress induced rats; CUMS+SERT: Chronic Unpredictable Mild Stress was treated with Sertraline; CUMS+ASHW: Chronic Unpredictable Mild Stress was treated with Ashwagandha