Effect of Heat Stress, Zinc, and Cholecalciferol (Vitamin D3) on the Cortisol and Cytokine-mediated Responses of Laboratory Rats in Kirkuk City, Iraq

Background: Both major and minor stressful events can have direct adverse effects on a variety of immunological mechanisms. Experimental data have shown that any improvement in vitamin D3 status can result in a major change in the expression of genes that affect biological disorders linked to vitamin D3 deficiency, such as cardiovascular diseases, autoimmune disorders, and cancer. Objectives: This study aimed to measure the effects of heat stress and zinc and vitamin D3 supplementation on serum cortisol, interleuken-6 (IL-6), and interferon-gamma (INF-g) levels in male rats.Methods: Five equal groups of rats (n=10) were assigned to different treatment groups as follows: control, heat stress(exposed to 35 °C for 2 hours/day), zinc (50 mg/kg diet), vitamin D3 (50 μg/kg of diet), and combined intervention (heat stress plus zinc and vitamin D3 supplementation). The treatment regimen lasted for four weeks. Results: Statistically significant differences were reported for all comparisons of cortisol levels between the five treatment groups (P≤0.001) except between the control and vitamin D groups and between heat stress and zinc groups (P>0.05). Regarding the Il-6 levels, a statistically significant difference observed between all groups (P≤0.001) except between the control and zinc groups (P>0.05). Finally, statistically significant differences were also noticed regarding the IFN-g levels between all study groups, except in the heat stress and zinc groups compared to the control group (P>0.05). Conclusion: Heat stress and zinc and vitamin D3 supplementation can significantly affect the levels of stress-related hormones and the expression of immune response–stimulating cytokines. These findings suggest that physiological and nutritional factors are closely interlinked in modulating immune homeostasis.