Social defeat stress induces a depression-like phenotype in adolescent male c57BL/6 mice

Abstract

Exposure to stress is highly correlated with the emergence of mood-related illnesses. Because major depressive disorder often emerges in adolescence, we assessed the effects of social defeat stress on responses to depressive-like behaviors in juvenile mice. To do this, postnatal day (PD) 35 male c57BL/6 mice were exposed to 10 days of social defeat stress (PD35–44), while control mice were handled daily. Twenty-four hours after the last episode of defeat (PD45), separate groups of mice were tested in the social interaction, forced swimming, sucrose preference, and elevated plus-maze behavioral assays (n = 7–12 per group). Also, we examined body weight gain across days of social defeat and levels of blood serum corticosterone 40 min after the last episode of defeat stress. Our data indicates that defeated mice exhibited a depressive-like phenotype as inferred from increased social avoidance, increased immobility in the forced swim test, and reduced sucrose preference (a measure of anhedonia), when compared to non-defeated controls. Defeated mice also displayed an anxiogenic-like phenotype when tested on the elevated plus-maze. Lastly, stressed mice displayed lower body weight gain, along with increased blood serum corticosterone levels, when compared to non-stressed controls. Overall, we show that in adolescent male c57BL/6 mice, social defeat stress induces a depression- and anxiety-like phenotype 24 h after the last episode of stress. These data suggest that the social defeat paradigm may be used to examine the etiology of stress-induced mood-related disorders during adolescence.

In tribute to Bob Blanchard: Divergent behavioral phenotypes of 16p11.2 deletion mice reared in same-genotype versus mixed-genotype cages

“…In particular, sexual and reproductive behaviors were severely suppressed in subordinate male rats [1,5,22,[80][81][82][83][84][85][86]. Studies from other laboratories indicated similar aversive effects of social stress on physiological processes and social behaviors in mice [87][88][89][90]. As in rats, subordinate male mice were found to emit fewer ultrasonic vocalizations and exhibited reduced sexual behaviors as compared to dominant male mice [91][92][93][94].…”

Effects of social stress and clomipramine on emotional memory in mice

“…Van Kampen et al 2000) and mice (e.g. Iñiguez et al 2014). In contrast, other studies have reported no significant decrease in activity (Monleón et al 2015(Monleón et al , 2016 or hyperactivity (Venzala et al 2013).…”

“…Watt et al 2009, Toth andNeumann 2013) and depression (e.g. Venzala, et al 2012, Iñiguez et al 2014, in order to determine the underlying mechanisms and identify potential pharmacological treatments.…”

Evidence for the role of corticotropin-releasing factor in major depressive disorder

“…Recent work has characterized chronic stress as one of the primary causal factors for the development and persistence of depressive behavioral phenotypes (Iniguez et al, 2014; Kleiman et al, 2014; Mahar et al, 2014; Monroe et al, 2014; Morris et al, 2014; Nederhof et al, 2014; Saravanan and Wilks, 2014; Shapero et al, 2014; Sickmann et al, 2014; Vinkers et al, 2014). In addition, exposure to stressful life events synergistically interacts with residual depressive symptoms (i.e., high depression scores following therapeutic interventions), to increase the risk of relapsing to a depressed state (Harkness et al, 2014).…”