Neuroprotective effects of quercetin on memory and anxiogenic-like behavior in diabetic rats: Role of ectonucleotidases and acetylcholinesterase activities

The present study investigated the protective effect of quercetin (Querc) on memory, anxiety-like behavior and impairment of ectonucleotidases and acetylcholinesterase (AChE) activities in brain of streptozotocin-induced diabetic rats (STZ-diabetes). The type 1 diabetes mellitus was induced by an intraperitoneal injection of 70 mg/kg of streptozotocin (STZ), diluted in 0.1 M sodium-citrate buffer (pH 4.5). Querc was dissolved in 25% ethanol and administered by gavage at the doses of 5, 25 and 50 mg/kg once a day during 40 days. The animals were distributed in eight groups of ten animals as follows: vehicle, Querc 5 mg/kg, Querc 25 mg/kg, Querc 50 mg/kg, diabetes, diabetes plus Querc 5 mg/kg, diabetes plus Querc 25 mg/kg and diabetes plus Querc 50 mg/kg. Querc was able to prevent the impairment of memory and the anxiogenic-like behavior induced by STZ-diabetes. In addition, Querc prevents the decrease in the NTPDase and increase in the adenosine deaminase (ADA) activities in SN from cerebral cortex of STZ-diabetes. STZ-diabetes increased the AChE activity in SN from cerebral cortex and hippocampus. Querc 50 mg/kg was more effective to prevent the increase in AChE activity in the brain of STZ-diabetes. Querc also prevented an increase in the malondialdehyde levels in all the brain structures. In conclusion, the present findings showed that Querc could prevent the impairment of the enzymes that regulate the purinergic and cholinergic extracellular signaling and improve the memory and anxiety-like behavior induced by STZ-diabetes.