Assessing the Effect of Diazepam on Methamphetamine-induced Seeking Behavior in Rats

 Relapse is a common problem in substance-use disorders. Accumulating evidence has shown that diazepam can reduce the abuse potential of some drugs.

 We investigated the effects of diazepam during and after the withdrawal period on the reinstatement of conditioned place preference (CPP) induced by a single dose of methamphetamine in male Wistar rats.

 Three groups of rats were trained to acquire methamphetamine CPP. The rats in the control group received, respectively, saline and methamphetamine (1 mg/kg, daily, ip) in the extinction and priming phases. Two other groups (one and two) had a similar process, but the rats in group one received diazepam (3 mg/kg, daily, ip) in the extinction phase and those in group 2 received a single dose of diazepam just before the priming phase. The CPP was checked daily during all processes.

 We showed that a 3-day period injection of methamphetamine (1 mg/kg) resulted in a positive conditioning score on the first day after conditioning. Also, 3 mg/kg of diazepam daily in the extinction period shortened the withdrawal period for one day and extinction happened on the 9th and 10th days. Diazepam also reduced the conditioning score at the reinstatement phase (P < 0.01). Furthermore, diazepam injection (3 mg/kg) before the methamphetamine priming dose did not have any significant effect on the reinstatement of drug-seeking.

 This study demonstrated that administration of diazepam during the extinction period was associated with reduced maintenance and reinstatement of methamphetamine-induced CPP, while the single dose of diazepam could not prevent the reinstatement of methamphetamine.