Fig. 2.
METH-induced reinstatement of CPP (METH) and subsequent blocking of reinstatement with R,S-GVG (GVG + METH). The average percentage of time spent in the METH-paired and saline-paired chambers, across all dosage groups, is presented for two consecutive days. On the first day (designated as METH), rats in all dosage groups were re-exposed to a challenge dose of METH following a period of extinction. Upon re-exposure to METH, paired Student’s t-tests revealed that animals in all dosage groups spent a significantly greater average percentage of time in the METH-paired chamber over the saline-paired chamber, exhibiting a reinstatement of the CPP (p < 0.05 indicated by *). Specifically, the 1.0, 2.5, 5.0, and 10.0 mg/kg groups spent an average of 62.7% (p = 0.02), 64.4% (p = 0.0118), 63.5% (p = 0.0033), and 70.7% (p = 0.0043) of the time in the METH-paired chamber, respectively. On the second day (designated as GVG + METH), animals were pretreated with R,S-GVG (300 mg/kg, i.p.) 2.5 hours prior to the same METH challenge. Pretreatment with R,S-GVG blocked reinstatement in all dosage groups, as paired Students t-tests revealed that the average percentage of time animals in each dosage group spent in the METH-paired and saline-paired chambers was no longer significantly different. As can be seen, rats in the 1.0, 2.5, 5.0, and 10.0 mg/kg groups spent an average of 54.0% (p = 0.377), 59.3% (p = 0.337), 49.3% (p = 0.4796), and 48.8% (p = 0.4577) of the time in the METH-paired chamber.