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

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.