Synergic effects of Trigonella foenum-graecum, Ribes rubrum, Lavandula angustifolia, and Arctium Lappa extracts mixture on learning and memory deficits in streptozocin-induced diabetic rats

Objective(s): The present study aimed to assess the efficacy of some known extracts on learning and memory impairment induced by streptozocin (STZ) in male rats.Materials and Methods: Eighty male rats were randomly divided: 1) control, 2) STZ (50 mg/kg), 3) STZ+Trigonella foenum-graecum (200 mg/kg), 4) STZ+Ribes rubrum (500 mg/kg), 5) STZ+Lavandula angustifolia (400 mg/kg), 6) STZ+Arctium Lappa (200 mg/kg), 7) STZ+mix of extracts (quarter dose of each extract), and 8) STZ+metformin (100 mg/kg). Treatment was continued for 8 weeks and the after that, the behavioral tests related to learning and memory including Morris water maze (MWM) and passive avoidance (PA) were performed along with biochemical analysis associated with oxidative stress pathway and other related indicators.Results: According to the results, all extracts demonstrated potential effect to ameliorate cognitive impairment caused by STZ in both MWM and PA tests along with attenuating oxidative stress indicators like malondialdehyde (MDA), while total thiol content and anti-oxidant enzyme activity like superoxide dismutase (SOD) and Catalase (CAT) remarkably increased in biochemical test results. Interestingly, the mixture of extracts illustrated much better results in ameliorating the brain-derived neurotrophic factor (BDNF), while attenuating the amyloid-B and glial fibrillary acidic protein (GFAP).Conclusion: The present study demonstrated these extracts alone or in combination with a minimum dose have a strong potential to ameliorate learning and memory impairment induced by STZ along with lowering glucose levels by which they prevent or manage diabetes. It is noteworthy that the results matched those of metformin a well-known anti-diabetic drug.