The opposite effect of intra-VTA bupropion on chewing and escape attendance behaviors of morphine withdrawal syndrome in rat.

Bupropion is a unique, non-nicotinic smoking cessation agent despite its effective antidepression effect. It is a NE and DA reuptake inhibitor and as well as a nicotinic acetylcholine receptor antagonist. Beside its smoking cessation effects it can reduces some symptoms of nicotinic withdrawal signs. DA neurons such as VTA neurons play essential roles in depression and drug dependence. This study was tested the short-term effect of intra VTA injection of bupropion on naloxone precipitated withdrawal syndrome escape attendance and chewing signs.

Materials & Methods : The sham group received saline as drug vehicle but treated groups received 0.25, 1.25 and 2.5 mg/μl/min of bupropion in VTA stereotaxically, and control group had surgery but had no any injection in VTA. Morphine dependence was carried out under standard protocol (i.p., 4 days, 3 time in each day with incremental doses 15, 20, 25, and 30 mg/kg). Withdrawal signs were precipitated by naloxone (1.2 mg/Kg, s.c.), observed continuously and registered on-line each minute. The behaviors captured by 3 digital cameras indifferent view (30 min) for offline analysis.

Results : Signs were counted and analyzed within and between groups by one-way ANOVA. The analysis of data showed that bupropion can decrease escape attendance behavior in a dose dependent approach but it can increase the chewing in dose dependent manure. The differences were significant between sham and treated groups.

Conclusions : It concluded that bupropion can alter the opioid withdrawal signs in different directions and it can alter the pattern of withdrawal outcomes.