Transcriptional effects of chronic heroin and methamphetamine treatment in the mouse striatum

To identify molecular effects of chronic drug treatment, heroin and methamphetamine treated animals were compared with saline treated animals at multiple time-points using microarray technology. Gene expression profile was assessed 14 h after the last dose of 1, 3, 6 or 12 days drug treatment and after 13, 15, 18 or 24 days of withdrawal. Animals were injected intraperitoneally with saline (SAL) (Polfa, Lublin, Poland), heroin (synthesized from morphine in Institute of Pharmacology PAS, Krakow, Poland) or D-methamphetamine (Sigma-Aldrich, Poznan, Poland) twice a day for consecutive 12 days in increasing doses. The Methamphetamine last dose (8 mg/kg) was four times greater than the first dose (2 mg/kg). It was also the case for heroin (40 and 10 mg/kg respectively). Mice were sacrificed by decapitation after 1, 3, 6 or 12 days of treatment or after 13, 15, 18 or 24 days of withdrawal.