Melatonin Modulates the Immune System Response and Inflammation in Diabetic Rats Experimentally-Induced by Alloxan

Diabetes mellitus (DM) is a metabolic disease, which causes an increase in the proinflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β), and also proliferation of monocyte chemotactic protein. In the present study, the potential effects of melatonin on proinflammatory cytokines, hematological values, and lymphoid tissues were investigated in diabetic rats. In the study, 36 male rats were randomly divided into 4 groups as follows: Control, Mel (melatonin), DM, and DM-Mel. For 15 days, an isotonic saline solution was given to the Control and DM groups; melatonin was administered to the Mel and DM-Mel groups intraperitoneally. At the end of the study, all animals were sacrificed by drawing the blood from their hearts under deep anesthesia. Samples of the spleen, thymus, and lymph nodes were fixed in 10% formaldehyde for histologic analysis. Increases in proinflammatory serum cytokine concentrations, mast cells, and total white blood cell counts as well as tissue destruction in the lymphoid organs were determined in the DM group via biochemical, hematological, and histologic analyses. However, the findings for the DM-Mel group revealed decreases in serum IL-1β concentration and mast cell densities, and destructions in lymphoid tissues by the melatonin administration. The present study suggests that melatonin treatment may control immune system regulation and inhibit the production of proinflammatory cytokines and tissue mast cell accumulation by preventing the destruction of lymphoid organs in the diabetic process.