[Accelerated angiotensinogen gene expression in the rat brain made tolerant to morphine or electroacupuncture...

The aim of the present study was to explore whether the expression of angiotensinogen (Ang) gene was accelerated during the development of morphine tolerance or electroacupuncture tolerance. The total rat brain RNA was extracted by phenol, and dot blot hybridization with synthetic Ang oligo-DNA was adopted for measuring Ang mRNA. Autoradiographic examination revealed a marked increase in Ang mRNA in rats receiving multiple injections of morphine or continuous electroacupuncture (EA) stimulation for several hours. The integrated O.D. (I.O.D.) of the hybridized dots revealed a 1-fold and 8-fold increase in Ang mNRA in rats receiving morphine injection for 1 and 4 days, respectively, and a 5-fold and 13-fold increase in rats receiving 3 and 6h EA stimulation, respectively. The results suggest that transcription of Ang gene in rat brain can be accelerated within 3-4h by continuous morphine or EA stimulation and that a longer lasting stimulation resulted in a stronger gene expression.