Brain cytochromes P-450 are responsive to phenobarbital and tricyclic amines

Cytochrome P-450 form b has been detected for the first time in rat brain by cross-hybridization of poly(A+) RNA with a radiolabelled cDNA probe. The cross-hybridizable material was easily detectable in rats after treatment with phenobarbital but not in untreated rats. Moreover, treatment of rats with amitriptyline or imipramine, tricyclic antidepressants in wide therapeutic use for depression, markedly increases the amount of RNA species hybridizing with P-450b cDNA probe in comparison to untreated controls. These observations raise the issue of a possible role for brain cytochromes P-450 in the metabolism of drugs such as the tricyclic antidepressants.