Investigation of the Effect of Intranasal Oxytocin Application on Learning and Memory of Chronic Cold Stress in Rats Depending on Gender

INTRODUCTION: If the severity of the stressor exceeds the threshold level of the body, this situation may disrupt homeostasis and cause some diseases. The aim of this study was to investigate the effects of exogenous oxytocin application on spatial learning performance of rats exposed to chronic cold stress.
METHODS: 39 male and 40 female adult Wistar albino rats were used. Rats were divided into CNT, OT, CS and CSO groups as male and female. Rats in CS and CSO groups were kept at +4 ºC for 2 hours for 21 days. Intranasal oxytocin (1 µg/µl; 2x10 µl) was applied bilaterally to rats in OT and CSO groups. Then, Morris Water Tank (MWM) experiments were performed. Hormone levels were measured in the blood samples taken and histopathological examinations were performed in brain tissue.
RESULTS: In MWM learning trials, the CSO group found the hidden platform later in both male and female rats. In the probe phase where memory performance was evaluated, it was observed that memory processes of all groups were preserved, however, in female rats, the CSO group spent less time in the target quadrant. Plasma corticosterone levels were found to be significantly higher in the CSO group in male and female rats. In male rats, the dentate gyrus granule cell layer was significantly thinner in the CSO group.
DISCUSSION AND CONCLUSION: Chronic cold stress impaired learning performance in male rats but did not cause any change in female rats. It was observed that intranasal oxytocin administration to stressed rats further deepened spatial learning impairment.