Melatonin protects retinal tissue damage in streptozotocin-induced aged rats.

OBJECTIVES: The aim of this study was to investigate how melatonin administration affects retinal oxidative damage and retinal SIRT1 gene activation in diabetic elderly female rat model. METHODS: 16-months-old female rats were used in the study. A total of 24 rats were divided into 4 groups in equal numbers: Group 1. Control, Group 2. Control + Melatonin, Group 3. Diabetes, Group 4. Diabetes + Melatonin. In group 3 and 4 rats, diabetes was induced by intraperitoneal (IP) injection of streptozotocin. Groups 2 and 4 were given ip melatonin for 4 weeks. SIRT-1 gene expression was determined by PCR method and GSH and MDA levels by ELISA in retinal tissue samples taken from animals sacrificed under general anesthesia. RESULTS: In our study, the highest retinal SIRT1 expression values were obtained in the diabetes + melatonin (G4) group. The retinal SIRT1 expression values of the diabetes group (G3) were lower than group 4 and higher than the general control (G1) and control + melatonin (G2) groups. Again in our study, the highest retinal MDA values were obtained in the diabetes group (G3). The highest retinal GSH values were obtained in the Diabetes + melatonin group (G4). CONCLUSION: The results of our study showed that melatonin supplementation has a protective effect on retinal tissue in a diabetic elderly female rat model. This protective effect of melatonin supplementation occurs by increasing both retinal antioxidant activity and retinal SIRT1 gene expression.

The effects of resveratrol and melatonin on biochemical and molecular parameters in diabetic old female rat hearts.

The roles of melatonin and resveratrol-enhanced activation of SIRT1 (silent information regulator 1), GLUT4 (glucose transporter type 4), and PGC-1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha) in mediating the protective effects on the heart in aged female rats with streptozotocin-induced diabetes were investigated. 16-month-old 48 Wistar female rats were separated into 8 groups with equal numbers. Group 1: Control, Group 2: Resveratrol Control, Group 3: Melatonin Control, Group 4: Resveratrol and Melatonin Control, Group 5: Diabetes, Group 6: Diabetes Resveratrol, Group 7: Diabetes Melatonin, Group 8: Diabetes Resveratrol and Melatonin. A single dose of 40 mg/kg intraperitoneal streptozotocin was injected into the rats of Groups 5, 6, 7, and 8 to induce experimental diabetes. Blood glucose levels were measured from the tail veins of the animals six days after the injections, using a diagnostic glucose kit. Rats with a blood glucose levels ≥300 mg/dl were considered diabetic. 5 mg/kg/day of resveratrol (intraperitoneal) and melatonin (subcutaneous) were administered for four weeks. At the end of the applications, SIRT1, GLUT4, PGC-1α gene expression as well as MDA and GSH levels in the heart tissues were determined by the PCR method from heart tissue samples taken under general anesthesia. The findings of our study show that suppressed antioxidant activity and decreased GLUT4, SIRT1, and PGC-1α gene expression in heart tissue can be reversed by the combination of resveratrol, melatonin, and resveratrol + melatonin in a diabetic aged female rat model. Resveratrol and melatonin supplementation may have a protective effect on cardiac functions in the diabetic aged female rat model.