Ability of palatable food consumption to buffer against the short- and long-term behavioral consequences of social defeat exposure during juvenility in rats

In adult rats, access to a palatable diet can buffer against the effects of stressors. Approximately 10% of all adolescents are repeatedly victimized by their peers raising the possibility that palatable food consumption may be relevant to this developmental window. This study assessed the long-term impact of juvenile social defeat exposure on anxiety and depressive-like behavior and whether daily limited access to a palatable diet moderated these behavioral consequences. We also investigated the impact of the palatable diet on behavior during the defeat sessions. Juvenile rats were exposed to either a different adult resident rat (Stress) or handling (Control) from postnatal day (PD) 28-34. All rats had ad libitum access to either chow alone or both chow and limited access (4 h/day) to palatable food commencing on PD 21. Results showed that during the defeat sessions, juvenile rats with access to the palatable diet spent less time in submissive postures and displayed significantly longer latencies to submit to the resident. In adulthood, previous exposure to juvenile social defeat resulted in a mild anxiogenic profile in the open field among rats with access to Chow only. Furthermore, defeated rats, regardless of diet, displayed reduced locomotor activity and increased social interaction as adults. These findings suggested only minimal enduring negative consequences from juvenile social defeat exposure which made it challenging to assess potential stress-buffering effects of the palatable diet. This was not the case during the defeat sessions where previous exposure to palatable food appeared protective against the acute stressor effects.