Adolescent social stress and social context influence the intake of ethanol and sucrose in male rats soon and long after the stress exposures

Abstract

Social instability stress in adolescent rats (SS; postnatal day 30–45, daily 1 hr isolation +new cage partner) alters behavioural responses to psychostimulants, but differences in voluntary consumption of natural and drug rewards are unknown. SS also is associated with an atypical behavioural repertoire, for example reduced social interactions. Here, we investigated whether SS rats differ from control (CTL) rats in ethanol (EtOH) or sucrose intake in experiments involving different social contexts: alone, in the presence of an unfamiliar peer, in the presence of its cage partner, or in competition against its cage partner. SS rats drank more EtOH than CTL rats irrespective of social context, although the effects were driven primarily by those tested soon after the test procedure rather than weeks later in adulthood. SS and CTL rats did not differ in sucrose intake, except in adulthood under conditions of competition for limited access (SS>CTL). Adolescent rats drank more sucrose than adults, in keeping with evidence that adolescents are more sensitive to natural rewards than adult animals. Overall, adolescent SS modified the reward value of EtOH and sucrose, perhaps through stress/glucocorticoids modifying the development of the mesocorticolimbic system.

Social Interaction With an Alcohol‐Intoxicated or Cocaine‐Injected Peer Selectively Alters Social Behaviors and Drinking in Adolescent Male and Female Rats

“…Previous research in rats found that when both animals, the demonstrator and the observer (combined exposure), were intoxicated, there was an increase in EtOH consumption, suggesting that when both peers of the dyad are intoxicated, this potentiates the risk for increased adolescent EtOH consumption (Eade et al, ). Recently, it was shown that social instability stress (isolated for 1 hour and then placed with a new cage mate daily) during adolescence (PND 30 to 45) increased intake of EtOH, but not sucrose, when male rats were tested during adolescence (Marcolin et al, ), suggesting that changes in social interaction mediate overall changes in EtOH intake in adolescent male rats. However, these results were not supported in the current study, as changes in EtOH intake were only observed in female adolescent rats.…”

“…Social influences on alcohol drinking have received attention using rodent models (Doremus et al, ; Eade et al, ; Fernández‐Vidal and Molina, ; Gauvin et al, ; Hunt et al, ; Juárez and De Tomasi, ; Marcolin et al, ; Varlinskaya and Spear, ; Varlinskaya et al, ; Varlinskaya et al, ; Varlinskaya et al, ). In animal models of social influence on alcohol drinking, the most commonly studied behaviors include social play, social investigation, and social contact (Maldonado‐Devincci et al, ; Marcolin et al, ; Varlinskaya and Spear, ; Varlinskaya et al, , ). Adolescent animals seek environmental cues paired with social interactions (Calcagnetti and Schechter, ), and male rats are particularly sensitive to these effects (Maldonado‐Devincci et al, ).…”

Social interaction with an alcohol-intoxicated or cocaine-injected peer selectively alters social behaviors and drinking in adolescent male and female rats

“…Previous research conducted in rats found that when both animals, the demonstrator and observer (combined exposure) were intoxicated, there was an increase in alcohol consumption, suggesting that when both peers of the dyad are intoxicated this potentiates the risk for increased adolescent alcohol consumption (Eade, Youngentob and Youngentob, 2016). Recently, it was shown that social instability stress (isolation for one hour then placed with a new cage mate daily) during adolescence (PND 30-45) increased intake of ethanol, but not sucrose, when male rats were tested during adolescence (Marcolin et al , 2019), suggesting that changes in social interaction mediate overall changes in ethanol intake in adolescent males. However, these results were not supported in the current study, as changes in ethanol intake were only observed in female adolescent rats.…”

“…Social influences on alcohol drinking have received attention using rodent models (Gauvin et al , 1994; Juárez and De Tomasi, 1999; Hunt, Holloway and Scordalakes, 2001; Varlinskaya, Spear and Spear, 2001; Varlinskaya and Spear, 2002; Fernández-Vidal and Molina, 2004; Doremus et al , 2005; Varlinskaya, Vogt and Spear, 2013; Varlinskaya, Truxell and Spear, 2015; Eade, Youngentob and Youngentob, 2016; Marcolin et al , 2019). In animal models of social influence on alcohol drinking, the most commonly studied behaviors include social investigation, social play, and social contact (Varlinskaya, Spear and Spear, 2001; Varlinskaya and Spear, 2002; Maldonado-Devincci, Badanich and Kirstein, 2010; Varlinskaya, Truxell and Spear, 2015; Marcolin et al , 2019). Adolescent animals seek environmental cues paired with social interactions (Calcagnetti and Schechter, 1992) and males are particularly sensitive to these effects (Maldonado-Devincci, Badanich and Kirstein, 2010).…”

Social instability in adolescence differentially alters dendritic morphology in the medial prefrontal cortex and its response to stress in adult male and female rats

“…Male rats subjected to social instability in adolescence show reduced social interactions both immediately following the cessation of stress (Hodges et al, ) and in adulthood (Green, Barnes, & McCormick, ). The same manipulation results in increased ethanol intake in adolescent males (Marcolin, Hodges, Baumbach, & McCormick, ), and remodels dendrites in the medial amygdala (Hodges, Louth, Bailey, & McCormick, ).…”