Microarray profile analysis of toxic cocaine-induced alterations in the expression of mouse brain gene sequences: a possible 'protective' effect of buprenorphine

Using a mouse brain cDNA microarray consisting of 2688 gene sequences, which include unknown sequences with the empirical possibility of expression in the brain, the effects of repeated toxic doses of intraperitoneal (i.p.) cocaine (40 mg kg−1, 4 days) on the expression profile of the cerebral genes were investigated. The modifications in this profile caused by buprenorphine (BUP) (0.25 mg kg−1 i.p., 4 days), a protective drug against cocaine, were also examined. In the cocaine group, the expression levels reached the recommended increased levels (≥2 times the control value in the saline‐treated control group) in 24.0% of the genes but were equal to or less than the recommended attenuation levels (≤0.5 times the control value) in 14.0% of the genes. In the cocaine–BUP group, the expression levels of the other 15.4% of the total genes were increased and those of the other 18.2% of the total genes were attenuated. However, corresponding to the BUP‐attenuated mortality rate and severity of seizures, the expression levels of 80.1% of the cocaine‐modified genes with above‐background levels recovered to the recommended normal levels (>0.5 and