Metformin Improves Metabolic Memory in High Fat Diet (HFD)-induced Renal Dysfunction.

Recently, we have shown that high fat diet (HFD) in vivo and in vitro generates metabolic memory by altering H3K36me2 and H3K27me3 on the promoter of FOXO1 (transcription factor of gluconeogenic genes) (Kumar, S., Pamulapati, H., and Tikoo, K. (2016) Mol. Cell. Endocrinol. 422, 233-242). Here we checked the hypothesis whether concomitant diet reversal and metformin could overcome HFD-induced metabolic memory and renal damage. Male adult Sprague-Dawley rats were rendered insulin-resistant by feeding high fat diet for 16 weeks. Then the rats were subjected to diet reversal alone and along with metformin for 8 weeks. Biochemical and histological markers of insulin resistance and kidney function were measured. Blood pressure and in vivo vascular reactivity to angiotensin II (200 ng kg-1) were also checked. Diet reversal could improve lipid profile but could not prevent renal complications induced by HFD. Interestingly, metformin along with diet reversal restored the levels of blood glucose, triglycerides, cholesterol, blood urea nitrogen, and creatinine. In kidney, metformin increased the activation of AMP-activated protein kinase (AMPK) and decreased inflammatory markers (COX-2 and IL-1β) and apoptotic markers (poly(ADP-ribose) polymerase (PARP) and caspase 3). Metformin was effective in lowering elevated basal blood pressure and acute change in mean arterial pressure in response to angiotensin II (Ang II). It also attenuated tubulointerstitial fibrosis and glomerulosclerosis induced by HFD feeding in kidney. Here we report, for the first time, that metformin treatment overcomes metabolic memory and prevents HFD-induced renal damage.