Selenium nanoparticles and metformin ameliorate streptozotocin-instigated brain oxidative-inflammatory stress and neurobehavioral alterations in rats

Selenium nanoparticles (SeNPs) are well reported to exhibit pharmacological activities both in vitro and in vivo. However, literature is devoid of studies on the impact of SeNPs and/or metformin (M) against streptozotocin (STZ)-mediated oxidative brain injury and behavioral impairment. Consequently, to fill this gap, diabetes was induced in male Wistar rats by feeding with 10% fructose solution for 2 weeks, followed by a single dose intraperitoneal injection of STZ (40 mg/kg body weight [bwt]). After rats were confirmed diabetic, they were treated orally with 0.1 mg/kg bwt of SeNPs ± M (50 mg/kg bwt), and normal control (NC) received citrate buffer (2 mg/mL) for 5 weeks. In comparison with the diabetic control (DC), SeNPs, and/or M significantly (p < 0.05) lowered blood glucose levels, but increased insulin secretion and pancreatic β-cell function. An increase in locomotor and motor activities evidenced by improved spontaneous alternation, locomotor frequency, hinding, and increased mobility time were observed in treated groups. In addition, there was enhanced brain antioxidant status with a lower acetylcholinesterase (AChE) activity and oxidative-inflammatory stress biomarkers. A significant downregulation of caspase 3 and upregulation of parvalbumin and Nrf2 protein expressions was observed in treated groups. In some of the studied parameters, treated groups were statistically (p < 0.05) insignificant compared with the normal control (NC) group. Overall, co-treatment elicited more efficacy than that of the individual regimen. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s00210-020-02000-2) contains supplementary material, which is available to authorized users.