Preliminary Data on Some Behavioral Changes Induced by Short-Term Intraperitoneal Oxytocin Administration in Aged Rats.

INTRODUCTION: Oxytocin (OT) is a well-known neuropeptides which together with vasopressin, melatonin, insulin and other hormones can alter both behavior and physiological or neuronal functions. This growing interest on OT roles is also based on the demonstrated beneficial effects as a stress reliever and a social bonding agent. The association between old age and OT was only vaguely studied. Little or few is known on the effect of the OT hormone on the old body. Hereby, we present our preliminary results in the research on behavioral changes regarding the intraperitoneal administration of OT in aged rats.

SUBJECTS AND METHODS: OT was administered for 8 days in Wistar aged rats in parallel with saline administration for control group. Behavioral markers were assessed in some specific behavioral tasks, such as the Y-Maze test for short-term working memory, Open Field test, Elevated Plus Maze, and Forced Swim test for anxious and depressive behavior assessment, and Three-chambered Maze test for sociability assessment.

RESULTS: Increased mobility and decreased anxiety behaviors were reported for the aged intraperitoneal OT-treated animals, as compared with controls, during FST and OFT, and respectively FST, EPM, and OFT. Also, decreased depressive-like behaviors were observed in the same animal group during FST and ST. Moreover, a decrease in anxiolytic behavior was observed as exposed to stressful stimuli (such as grooming behavior in OFT, and forced grooming behavior in ST), and as exposed to social stimuli (such as grooming behavior in TCT). Similarly, significant differences were obtained regarding the social behavior of the intraperitoneal OT-treated animal as compared to control group, the animals showing increased sociability and social preference for the stranger animal in TCT. However, no significant effects on the working memory (assessed as spontaneous alternation in YMT) were observed.

CONCLUSIONS: Intraperitoneal administration of OT in aged rats has clear effects on anxious and depressive behavior, but no significant effects on the working memory. Also, several beneficial effects of OT on social preferences and sociability were observed.