Previous findings in our laboratory suggest that angiotensin Ⅱ (AⅡ) in thebrain is a powerful antagonist to the analgesic effect elicited by morphine andelectroacupuncture (EA) and plays an important role in the development ofEA and morphine-toterance. While the content of AⅡ-ir in the brain increaseddramatically in the rats subjected to repeated administration of EA or morphine

it was interesting to see whether the expression of angiotensinogen gene wasalso accelerated to cope with the increase in release. The samples of total RNAextracted from the brains of the rats were blotted to the Gene Screen membraneand hybridized with the synthetic

(32)

P end-labeled oligonucleotide DNA probe