Two Different Putative Genetic Animal Models of Childhood Depression

Background In an attempt to model childhood depression, we examined whether existing genetic animal models of depression in adult rats are also valid in prepubertal rats. Methods Two different “depressed” rat lines were studied: the Flinders Sensitive Line (FSL) and their controls, Sprague-Dawley (SD); and the Wistar Kyoto (WKY) line and their controls, Wistar. We hypothesized that male prepubertal FSL and WKY rats would show increased swim test immobility and different patterns of social play and of basal plasma levels of corticosterone and adrenocorticotropic hormone (ACTH) compared with control rats. Results Prepubertal FSL and WKY rats exhibited significantly longer duration of immobility than control rats in the swim test. The FSL rats demonstrated significantly higher levels of social play behaviors and lower levels of corticosterone and ACTH compared with SD control rats, whereas WKY rats demonstrated significantly lower levels of social play behaviors and higher plasma levels of corticosterone and ACTH compared with Wistar control rats. Conclusions The results might suggest that prepubertal FSL and WKY rats are both putative genetic animal models of childhood depression, exhibiting separate patterns and symptoms of childhood depression.