The changes of opiate receptor binding under electroacupuncture tolerance were studied in rat brain by autoradiography. Comparing with the results of electroacupuncture analgesia

the opiate re- ceptor binding was reduced significantly in rat brain after electroacupuncture tolerance.The nervous nuclei where the receptor binding decreased prominent- ly were:the dorsal part of cornu posterius

of the spinal cord

substantia grisea centralis medullae spinalis

nucleus tractus spinalis nerve trigemini

lo- cus coeruleus

raphe magnus

mucleus nucleus raphe dorsalis

substantia nigra

nucleus interpeduncularis cularis

substantia grisea centralis of mesencephalon

nucle ihabenulae

nuclei hypothalami

nuclei amygdalae

nucleus accumbens

etc. The authers point out that the nuclei involved in the electroacupuncture tolerance were the same to those in the electroacupuncture analgesia.The causes of the decrease of opiate receptor binding were disscused.