Don’t stress play time! On the interaction of social play and glucocorticoids

Tara C. Pimentel¹, E.J.M. Achterberg¹, J.G. Lozeman-van ’t Klooster¹, A.M. Baars¹, S. Kirchhoff¹, L.J.M.J. Vanderschuren¹, H.M.B. Lesscher<sup>1

1</sup> Department of Population Health Sciences, unit Animals in Science and Society, Faculty of Veterinary Medicine, Utrecht University, The Netherlands
AISS Behaviour NeurosciencedASS BW-1

Positive social interactions, like social play, are essential for social, cognitive, and emotional development. Play behaviour is initiated in the absence of severe stress. However, the influence of stress on play behaviour is inconclusive, with evidence from rat studies for reduced play behaviour in stressful situations and increased play behaviour after a chronic treatment with stress hormones. Glucocorticoids, including synthetic stress hormones, are the most prescribed anti-inflammatory drugs worldwide and appear to cause mood and memory changes in children. Because of its widespread use, its potential effect on play behaviour and the importance of play in development, it is crucial to understand the relation between glucocorticoids and play behaviour. Therefore, we aim to determine the role of glucocorticoids in social play behaviour in juvenile rats. To achieve that, we measured young rats’ social play behaviour after administration of the main glucocorticoid, corticosterone, or the corticosterone antagonist RU486. We found that acute administration of RU486 moderately decreased social play behaviour. Separately, we determined the effects of repeated corticosterone administration on play behaviour. Both play behaviour and baseline plasma corticosterone levels were moderately increased in rats that received 3 corticosterone injections over the course of 8 days. Taken together, these results suggest a modest positive relationship between corticosterone levels and play behaviour. In follow-up experiments we will examine the effects of the corticosterone synthesis blocker metyrapone to investigate the relation between endogenous corticosterone release and play behaviour. Moreover, considering the widespread usage of glucocorticoids, it is important to explore these results further by administering corticosterone in the same relative dosage and frequency as in children while monitoring the long-term effects on social play behaviour.