Morphine induces short-lived changes in G-protein gene expression in rat prefrontal cortex

Abstract

We have utilized a reverse transcriptase-polymerase chain reaction (RT-PCR) methodology followed by enzymatic restriction analysis to detect changes in G-protein mRNA levels in morphine-treated rats. The relative distribution of mRNA levels for GαoGαi1, Gαi2, Gβ1and Gβ2in the nucleus accumbens, striatum, locus coeruleus and prefrontal cortex was found to be similar to that previously estimated with other techniques. Morphine-induced changes of G-protein mRNA levels were detected only in the prefrontal cortex. Acute treatments (30 mg/kg, intraperitoneally) resulted in a significant increase of GαomRNA and significant decreases of Gαi1and Gαi2mRNAs. Chronic morphine administration (10-50 mg/kg over 14 days, intraperitoneally) increased Gβ1and Gαi1and Gαi2mRNAs levels to 148%, 410% and 451% of control, respectively. G-protein mRNA returned to control levels within 48 h of termination of the chronic treatments. The morphine-induced changes in G-protein mRNA levels may reflect changes in gene expression and could result in changes in G-protein levels affecting signal transduction pathways in chronically treated animals. © 2001 Elsevier Science B.V.