Effects of reducing or increasing olfactory stimulation upon the development of social play behavior in the rat

Abstract

The role of reduced or increased olfactory stimulation upon social play was investigated in male and female juvenile Wistar rats. One group of subjects was unilaterally deprived of olfactory input through the occlusion of a nasal pore by thermocauterization on postnatal day 3 (Experiment 1). In another group of animals the olfactory input was increased by daily exposure to amyl acetate vapors (10 min) from days 3 to 19 postpartum (Experiment 2). Social play behavior was recorded (5 min) on days 20, 25, 30, 40, 50, 60 and 70 postpartum. The thermocauterized animals of both sexes showed a significant increase in the frequency of social play compared to controls, and a significant decrease in the length, width and wet weight of olfactory bulbs (OB). By contrast rats with increased olfactory input exhibited reduced frequency of play only in females. The length and wet weight of OB were significantly increased in stimulated animals of both sexes. Current findings suggest that the reduction or increase of olfactory input, possibly altered the olfactory neural Substrate and consequently its connections with the amygdata, hippocampus, cingulum and Septum that modulate social play behavior.