Acute treatment with morphine augments the expression of serine racemase and d-amino acid oxidase mRNAs in rat brain

To obtain further insight into the interactions between the N-methyl-d-aspartate receptor and opioid receptor systems, we have investigated the effects of the acute treatment of morphine on the expression of serine racemase and d-amino acid oxidase mRNAs in several brain areas of rats. The morphine administration produced a dose-dependent and transient elevation in the levels of serine racemase and d-amino acid oxidase mRNAs in all the brain areas. The present results are the first to suggest an interaction between the expression of the mRNAs for the d-serine-related enzymes and the opioid receptor activation.