Antihyperglycemic activity of trigonelline and sitagliptin in nicotinamide-streptozotocin induced diabetes in Wistar rats

The objective of the present study was to evaluate the protective effect of trigonelline (TRIG) and sitagliptin (SITA) combination in streptozotocin-nicotinamide induced diabetes in Wistar rats. Diabetes was induced by streptozotocin (65 mg/kg i.p.) injected 15 min after nicotinamide (110 mg/kg, i.p.). The rats were divided into following groups: Group 1: non-diabetic control, Group 2: diabetic control (saline), Groups 3, 4, 5 received TRIG as 25, 50, 100 mg/kg p.o., Groups 6, 7, 8 received SITA as 2.5, 5, 10 mg/kg p.o. respectively. For acute study, serum glucose (SG) levels were measured at 0, 2nd, 4th, 6th and 24th hour after administration. To find out effective combination, acute study of TRIG + SITA combination was done. The doses used are in combination TRIG + SITA as Groups 9, 10, 11 as 70% + 30%, 50% + 50%, 30 + 70%. SG was measured as per above-mentioned pattern. A 28-day subacute study was performed by taking effective percentage combination of TRIG + SITA. For subacute study SG, body weight was measured on 7th, 14th, 21st, 28th day; while serum insulin, HbA_1c and pancreatic histopathological study were done on 28th day. In acute study, TRIG + SITA (50% + 50%) were more effectively 43.08% reduction in SG level at 6 h with onset at 2 h and effect waned at 24 h. Subacute study reveals that the TRIG + SITA (50% + 50%) reduces SG by 54.72% than alone on 28th day. Serum insulin levels, body weight, pancreatic mass were increased with reduction in HbA_1c levels in animals receiving 50% + 50% combination of TRIG + SITA. The concomitant administration of TRIG + SITA (50% + 50%) contributes in the prevention to development diabetes and showed synergistic antihyperglycemic effect.