Effects of oxytocin on behavior and neurotrophic factors in the brain of aged female rats exposed to chronic social isolation

Abstract

This study aimed to investigate the effects of social isolation stress and intranasally administered oxytocin on physiological and behavioral alterations during aging in rats. A total of 28, aged female Sprague-Dawley rats were allocated into four groups: control (C), social isolation (SI), oxytocin (O), and oxytocin+social isolation (OI). Animals in the SI and OI groups were housed in individual cages for four weeks. Intranasal oxytocin (2 μg/kg/day) was administered to the O and OI groups 14 times during the third and fourth weeks of the study. Behavioral assessments were conducted. Levels of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) were measured. In the Morris water maze test, all groups demonstrated improved learning performance, reflected by a progressive reduction in the time taken to locate the hidden platform. The three-chamber sociability test revealed that sociability was significantly impaired in the SI group but preserved in the O, OI, and C groups. VEGF levels in the prefrontal cortex were significantly reduced in the SI group compared to all other groups. Notably, VEGF levels were higher in the OI group than in the SI group. Hippocampal neuron density was lower in the SI group but was preserved in the OI group, suggesting a neuroprotective effect of oxytocin. These findings highlight the protective roles of oxytocin and sociability against the detrimental effects of chronic social isolation, particularly in preserving hippocampal neuron density and maintaining sociability and learning. Further research is needed to elucidate the molecular and behavioral mechanisms underlying these effects.