Methanolic extract of Euphorbia resinifera propolis improves cognitive functions in adult male rats with chronic unpredictable mild stress

Propolis is a substance marked by honeybees from plant resin to maintain hygienic environment in their hives. Prepuberty and adolescence criticality could be associated with diseases development and brain and memory dysfunctions in adult age. The study aimed to assess the effects of unpredictable chronic mild stress (UCMS) during prepuberty and adolescence and the propolis supplementation on cognitive functions in adult male rats. 18 adult male rats were divided into 3 groups of 6 rats: rats of control group (C) receive normal, stressed group (UCMS) exposed to 2 stressors/day for 6 weeks, and group (UCMS-MEP) exposed to 2 stressors/day for 6 weeks followed by oral supplementation of methanolic extract of propolis MEP (200 mg/kg/day) for 2 weeks. Memory was assessed by using object recognition test and Y-maze test, three-chamber sociability was used to assess social behaviors. Histological analyses of hippocampal and prefrontal cortex were performed. Chronic stress induced long-term memory loss and negative impact on working memory and social behavior deterioration at adulthood, histological analysis that UCMS caused damages in hippocampal and prefrontal cortex. The 15 days propolis supplementation improved memory performance in stressed rats by maintaining the integrity of hippocampal neurons in CA1 and CA3 regions. Also regulate social activity with an increase in the time spent with the stranger rat. Propolis extract exert enhancement effect on memory performance and regulative action on social activity restraining the damage in the prefrontal cortex and hippocampus.