The modulatory effects of tyrosol and nano-tyrosol on anxiety-like behavior and emotional memory in streptozotocin-induced diabetic rats

The effects of tyrosol and nano-tyrosol on the modulation of anxiety-like behavior and memory processes were evaluated in streptozotocin-induced diabetic rats. Male diabetic rats were orally treated with 1 ml of saline, nano-niosome, tyrosol, and nano-tyrosol (20 mg/dl) for 30 days. Anxiety-like behavior and memory process were evaluated by an elevated plus-maze (EPM) test-retest paradigm. The results showed that a single intraperitoneal (i.p.) administration of streptozotocin (50 mg/kg) raised blood glucose. While daily intragastric administration of tyrosol and nano-tyrosol reduced blood glucose. Induction of type II diabetes produced a distorted cellular arrangement whereas treatment with tyrosol and nano-tyrosol showed a typical cellular arrangement in the liver. Furthermore, induction of type II diabetes decreased %OAT (%open-arm time) but daily intragastric application of tyrosol (20 mg/dl) and nano-tyrosol (20 mg/dl) enhanced %OAT and %OAE (%open-arm entry) in the EPM when compared to the saline groups, showing anxiogenic- and anxiolytic-like effects, respectively. Also, induction of type II diabetes increased %OAT while daily intragastric administration of tyrosol (20 mg/dl) and nano-tyrosol (20 mg/dl) decreased %OAT and %OAE in the EPM in comparison to the saline groups, displaying impairment and improvement of emotional memory, respectively. Interestingly, nano-tyrosol exhibited the highest significant effect rather than tyrosol. Upon these results, we proposed the beneficial effects of tyrosol and nano-tyrosol on the modulation of anxiety-like behavior and memory processes in streptozotocin-induced diabetic rats.