Combined purslane ethanolic extract and metformin attenuate cognitive dysfunction in HFD/STZ-induced diabetic rats via modulation of oxidative stress, neuroinflammation, and neurotransmitters

BACKGROUND: Diabetes is associated with a number of significant long-term effects. In this study we consider that purslane which possesses numerous of pharmacological properties, and metformin, an antidiabetic drug, may have a therapeutic effects on diabetes-induced memory impairments in rats. METHODS: Forty male albino rats were randomly divided into five groups. Group I served as control group. The other four groups were first fed on HFD followed by a single interpretonial (i.p.) dose of STZ at a dose of (35) mg/kg then the groups were divided as following Group II diabetic group Group III, PEE group administered with oral dose of purslane ethanolic extract (100 mg/kg) for another four weeks. Group IV, MET group administered with oral dose of metformin (100 mg/kg) for another four weeks. Group V (PEE + MET) administered with oral dose of combination of both purslane ethanolic extract (50 mg/kg) and MET (50 mg/kg) for another four weeks. During the treatment rats were tested for memory and learning abilities (Morri's water maze test). Hippocampal samples were collected for biochemical, and histological measurements. Biochemical evaluation included (NO and TBARS) as an oxidative stress marker, (GSH, GPX, SOD, Catalase) as antioxidant, and inflammatory cytokines (tumor necrosis factor-α and interleukin-1β, interleukin-IL-6). Also, P-tau protein, (dopamine and GABA) as neurotransmitters, and for cholinergic system (acetylcholinesterase) were assessed, in addition to histological examinations of hippocampus. RESULTS: Diabetic rats showed a marked cognitive impairment in the Morris water maze test and alteration in the other biochemical and histological features. Intrestingly, PEE and MET treatments partially dramatically enhanced antioxidant levels. Also, reduced oxidative stress, pro-inflammatory mediators, and, phosphorylated tau levels. In addition, PEE and MET treatments partially modulated neurochemical profiles associated with memory function. The combined PEE + MET treatment showed the most pronounced improvement, reflecting synergistic effects. Individual data points highlighted consistent trends across animals. Also, it exhibited a significant restoration of normal hippocampal architecture, as confirmed by hematoxylin and eosin staining. CONCLUSIONS: The data obtained indicated that PEE, either alone or in combination with MET, has strong neuroprotective potential against STZ/HFD-induced diabetes. These safeguarding effects are probably because of its strong anti-inflammatory and antioxidant properties.