Social play test.

<p>The data represent the mean ± SEM of the following behaviours (n = 8): A) pouncing (jumping on or attacking the partner's nape); B) boxing/wrestling (rats stand on their hind paws and struggle using the forepaws); C) social grooming (sniffing or licking the partner); D) following/chasing (pursuing the partner); E) pinning (holding the partner in a supine position); and F) the total number of social play behaviours. Male (M) and female (F) rats were fed from weaning (at day 21 of life) and for 8 weeks with standard chow (ST) or the cafeteria diet (CAF). Two-way ANOVAs indicated that the cafeteria diet increased the frequency of pounces and pursuits and the total number of social behaviours (diet effect in all three variables <i>p</i><0.05). Females showed more pouncing, grooming and total number of behaviours than males (two-way ANOVA, gender: <i>p</i><0.05), as well as a residual increase in boxing (two-way ANOVA, p = 0.059). Males slightly increased the number of pursuits in comparison with females (two-way ANOVA, <i>p</i> = 0.098). ^abMean values with unlike letters were significantly different between groups (one-way ANOVA and Tukey's <i>post hoc</i> comparison, <i>p</i><0.05).