Differential effects of pair housing on voluntary nicotine
consumption: a comparison between male and female adolescent
Received: 26 November 2016 /Accepted: 24 April 2017 /Published online: 15 May 2017
Springer-Verlag Berlin Heidelberg 2017
Rationale Tobacco smoking occurs in a wide array of social
circumstances. Social support for quitting is generally used to
stop smoking, while peer interactions may be a crucial factor
in triggering tobacco use among adolescents.
Objectives To determine the role of social factors on nicotine
dependence, we compared single- and pair-housed rats sub-
jected to voluntary oral nicotine consumption tests.
Methods Six-week-old adolescent rats were subjected to ex-
perimental procedures and assigned to one of the following
groups: a male single group, a male pair group with a sibling, a
female single group, and a female pair group with a sibling. To
measure voluntary nicotine intake, we adopted a two-bottle
free-choice paradigm for each two days using 25 μg/ml and
100 μg/ml nicotine solution.
Results There were no differences in change in body weight or
food intake between the two groups of either sex. Pair-housed
female rats showed a reduction in nicotine consumption and
preference for both low- and high-dose nicotine solution, while
pair-housed male rats showed only reduced consumption and
preference for high-dose nicotine solution, but not low-dose so-
lution, as compared to single-housed male rats.
Conclusions Nicotine consumption is sex-dependently con-
trolled by the social circumstances of rats. This study broadens
our perspectives on the role of social interactions as a thera-
peutic strategy to treat nicotine addiction-related behaviors
depending on sex.
Nicotine intake facilitates further nicotine consumption,
which leads to addiction among tobacco users (Stead et al.
2008). The effects of nicotine that establish and maintain
tobacco-related habits result not only from prolonged stimu-
lation of brain reward systems, but also from a decrease in
initial aversive feelings towards tobacco (Dao et al. 2014;
Lee et al. 2015).
Social factors have a tremendous influence on drug abuse
(Kovács et al. 1998; Sarnyai and Kovács 2014; Young et al.
2011). Whereas weak social interactions increase vulnerabili-
ty to drug abuse and an insecure adult attachment style is a risk
factor for drug or alcohol abuse, strong adult-adult and adult-
offspring attachments play a protective role against drug use
and mitigate the risk of substance abuse (Caspers et al. 2005;
Ellickson et al. 1999; Vungkhanching et al. 2004). A previous
study revealed that orofacial contact by conspecifics reduced
the aversive properties of nicotine and increased nicotine self-
administration in adolescent rats (Chen et al. 2011).
Interestingly, social interaction serves as a neurophysiological
buffer that alleviates aversive responses such as stressor-
induced over-activation of brain cells and increased cortico-
sterone release in rats (Kikusui et al. 2006). Although not only
orofacial contact, but also full physical social interaction, is an
important communicative resource employed by rats, previ-
ous studies ignored the distinct roles of physical social inter-
action on nicotine intake.
Social interaction also works as effectively as a natural
reward to social animals (Trezza et al. 2010; Vanderschuren
et al. 2016). Previously, conditioned place preference tests
* Jihyun Noh
Department of Science Education, Dankook University, 152
Jukjeon-ro, Suji-gu, Yongin-si, Gyeonggi-do 16890, Republic of
Psychopharmacology (2017) 234:2463–2473