Relation of exploratory behaviour to plasma corticosterone and Wfs1 gene expression in Wistar rats

Male Wistar rats exhibit significant variations in exploratory behaviour in the elevated plus-maze (EPM) model of anxiety. We have now investigated the relation between exploratory behaviour and levels of corticosterone and systemic oxidative stress. Also, the expression levels of endocannabinoid-related and wolframin (Wfs1) genes were measured in the forebrain structures. The rats were divided into high, intermediate and low exploratory activity groups. Exposure to EPM significantly elevated the serum levels of corticosterone in all rats, but especially in the high exploratory group. Oxidative stress indices and expression of endocannabinoid-related genes were not significantly affected by exposure to EPM. Wfs1 mRNA level was highly dependent on exploratory behaviour of animals. In low exploratory activity rats, Wfs1 gene expression was reduced in the temporal lobe, whereas in high exploratory activity group it was reduced in the mesolimbic area and hippocampus. Altogether, present study indicates that in high exploratory activity rats, the activation of brain areas related to novelty seeking is apparent, whereas in low exploratory activity group the brain structures linked to anxiety are activated.