Effect of nicotine on quinpirole-induced checking behavior in rats: Implications for obsessive-compulsive disorder

Background: Rats treated chronically in a large, open field with the dopamine D-2/D-3 receptor agonist quinpirole (QNP) develop compulsive checking behavior as defined by a set of behavioral criteria. This paradigm has been suggested as an animal model of obsessive-compulsive disorder (OCD). Because nicotine blocks various behaviors induced by ontogenetic QNP administration, we asked whether nicotine could attenuate QNP-induced compulsive checking. Methods: Adult mate Long-Evans rats (n = 14/group) were treated twice weekly with saline (control), or with QNP (0.5 mg/kg) for 14-16 injections. On the last two injections, rats were pretreated in random order with an acute dose of nicotine (0.3 mg/kg base) or saline 10 min before administration of QNP or saline; and the effects on checking behavior was examined. The effects of chronic QNP treatment on nicotinic receptors in discrete brain regions were also determined. Results: Chronic QNP resulted in compulsive checking and increases in cerebellar alpha(4)beta(2) and alpha(7) nicotinic receptor densities. Nicotine pretreatment significantly reduced one of the three measures of compulsive checking behavior. Conclusions: Nicotine attenuates some symptoms of compulsive checking in a rat model of OCD; however, the mechanisms of this effect and therapeutic efficacy of nicotinic agonists in OCD require further study. Biol Psychiatry 2002;51:164-171 (C) 2002 Society of Biological Psychiatry.