Melatonin prevents kidney injury in a high salt diet induced hypertension model by decreasing oxidative stress.
J Pineal Res. 2015 Oct 14. Epub 2015 Oct 14. PMID: 26465239
Melatonin, a potent antioxidant molecule plays a role in blood pressure regulation. We hypothesized that melatonin may generate a protective effect in a high salt diet (HSD) rodent model mediated by decreasing renal oxidative stress. Dahl salt sensitive rats were divided into 3 groups according to diet: normal chow [control; HSD; HSD with melatonin (30/mg/kg/day) placed in their water (HSD+Mel) over an 8- week period. Blood pressure was measured by the tail cuff method. Kidney injury was evaluated by 24H urine protein excretion. Glomerular injury index (GII) (fibrotic glomeruli/100 glomeruli) was evaluated from a Masson's trichrom stained section. Kidney oxidative stress was determined by superoxide production via dihydroethidium staining. Expression of oxidative stress related genes was measured by RT-qPCR. Melatonin had no effect on blood pressure increase induced by HSD and attenuated proteinuria induced by HSD (HSD- 50.7±12, HSD+Mel- 22.3±4.3, controls- 6.5±1.0 gram protein/gram creatinine, p<0.001). HSD induced glomerular damage was significantly diminished by melatonin (GII in HSD -24±6, HSD+Mel-3.6±0.8, controls- 0.8±0.5. p<0.05). Superoxide production was significantly higher in kidneys of HSD fed rats than the controls (99±9 vs. 60±7 relative fluorescent units (RFU)/μm(2) , respectively, p<0.05). Melatonin also decreased superoxide production (74±5 RFU/μm(2) , p<0.05). The expression of kidney iNOS and p67(phox) mRNA was significantly higher in HSD than in the controls and HSD+Mel rats. Treatment with melatonin eliminated the deleterious effect of HSD in the kidneys of Dahl salt sensitive rats. The beneficial effect of melatonin is not mediated by lowering BP but by a direct anti-oxidative effect. This article is protected by copyright. All rights reserved.