EFFECTS OF REPEATED METHAMPHETAMINE ADMINISTRATION ON DOPAMINE D1 RECEPTOR, D2 RECEPTOR AND ADENYLATE-CYCLASE TYPE-V MESSENGER-RNA LEVELS IN THE RAT STRIATUM

Dopamine D1 receptor (D1R), D2 receptor (D2R) and adenylate cyclase ty pe V (AC5) mRNAs in the rat dorsal striatum(CPu) and ventral striatum (Acb) were measured by in situ hybridization histochemistry (ISHH) aft er repeated methamphetamine (MAP) administration. MAP (4 mg/kg) or an equivalent volume of saline was administered intraperitoneally once da ily for 10 days to male Wistar rats. After 7 days of abstinence, behav ioral experiment with MAP-challenge revealed that a significant behavi oral sensitization was achieved in MAP-treated animals. The animals we re sacrificed 7 days after the last injection and brain sections were analyzed by ISHH using S-35-labeled antisense oligonucleotide probes, We found that D1R mRNA levels in the CPu were significantly increased (124% of control, P < 0.01). In contrast, repeated MAP-treatment did n ot significantly affect the expression of D1R mRNA in Acb or mRNA for D2R or AC5. It was concluded that MAP-induced behavioral sensitization is accompanied by increased D1R mRNA levels in CPu. (C) 1997 Elsevier Science Ireland Ltd.