Effect of melatonin on antioxidant capacity, ınflammation and apoptotic cell death in lung tissue of diabetic rats

Abstract Purpose: To investigate the effects of melatonin on antioxidant capacity, inflammation and apoptotic cell death (through expression of cleaved-caspase 3) in lung tissue samples of diabetic rats. Methods: Thirty male Sprague-Dawley rats were randomly divided into three groups. Group 1 (control group) was made up of healthy rats. Group 2 (diabetes group) received streptozotocin at a dose of 50 mg/kg/day for 5 days.Group 3 (diabetes plus melatonin group) received streptozotocin at a dose of 50 mg/kg/day for 5 days and then they received melatonin at a dose of 20 mg/kg/day between 28thand 35thdays of the study. Results: Tissue MDA and MPO levels were found to be significantly higher in diabetes group compared to control group (p<0.05) whilst administration of melatonin was found to significantly lower this increase down to normal levels (p<0.05). Bronchus associated lymphoid tissue (BALT) was more severe in diabetics whereas administration of melatonin alleviated this hyperplasia. Cleaved caspase 3 activity was severe in hyperplastic BALT in diabetic rats however in lowered down to moderate level when melatonin was administered. Conclusion: The melatonin caused an increase in antioxidant capacity and decreased the expression of cleaved-caspase 3.

摘要 研究目的：探讨褪黑素对糖尿病大鼠肺组织抗氧化能力、炎症反应及细胞凋亡（通过检测剪切型半胱氨酸天冬氨酸蛋白酶3（cleaved-caspase 3）的表达水平）的影响。方法：将30只雄性Sprague-Dawley（SD）大鼠随机分为三组。第1组为对照组，由健康大鼠构成。第2组为糖尿病模型组，连续5天按50 mg/kg/日的剂量给予链脲佐菌素（streptozotocin）。第3组为糖尿病联合褪黑素干预组，先以50 mg/kg/日的剂量连续5天给予链脲佐菌素，随后在实验第28至35天，以20 mg/kg/日的剂量给予褪黑素干预。结果：与对照组相比，糖尿病模型组大鼠肺组织中的丙二醛（MDA）与髓过氧化物酶（MPO）水平显著升高（p<0.05）；褪黑素干预可显著降低该升高幅度，使其恢复至正常水平（p<0.05）。糖尿病大鼠的支气管相关淋巴组织（BALT）增生程度更为显著，褪黑素干预可缓解该增生现象。糖尿病大鼠增生的支气管相关淋巴组织中剪切型半胱氨酸天冬氨酸蛋白酶3活性显著升高，而褪黑素干预可将其活性降至中等水平。结论：褪黑素可提升肺组织的抗氧化能力，并下调剪切型半胱氨酸天冬氨酸蛋白酶3的表达。