Combined vildagliptin and memantine treatment downregulates expression of amyloid precursor protein, and total and phosphorylated tau in a rat model of combined Alzheimer's disease and type 2 diabetes

There is increasing evidence of a link between type 2 diabetes mellitus (T2DM) and cognitive decline. T2DM has been recognized as a risk factor for Alzheimer's disease (AD). The aim of this research was to investigate the biochemical and physiological effects of vildagliptin treatment alone, and in combination with memantine, in a rat model of combined T2DM and AD. The experimental study was carried out on 75 male Wistar rats weighing 180-200g. The rats were divided into five groups (n=15): normal group, Alzheimer diabetic control, treated with vildagliptin (10mg/kg/day), treated with memantine (30mg/kg/day), and treated with combination of drugs. Serum glucose, lipid profile, acetylcholinesterase (AChE), homocysteine (Hcy), and amyloid beta peptide (A) were determined. Lipid peroxidation was measured in brain tissue. Expression of amyloid precursor protein (APP) in the brain was assessed by q-PCR, and expression of total and phosphorylated tau was determined by Western Blotting. Vildagliptin alone and in combination with memantine caused a decrease in blood glucose, HOMA-IR, lipid profile, Hcy, malanodialdhyde, and acetylcholinesterase, and an increase in apolipoprotein E. Expression of APP and phosphorylated tau protein was decreased with combined vildagliptin and memantine treatment. In conclusion, vildagliptin treatment, either alone or in combination with memantine, modulates AD-associated biochemical changes and downregulates amyloid precursor protein and phosphorylated tau expression in diabetic rats.