BRAIN SUBSTRATES ACTIVATED BY ELECTROACUPUNCTURE OF DIFFERENT FREQUENCIES .1. COMPARATIVE-STUDY ON THE EXPRESSION OF ONCOGENE C-FOS AND GENES-CODING FOR 3 OPIOID-PEPTIDES

Low and high frequency electroacupuncture (EA)-produced analgesia have been shown to be mediated by different brain substrates and different opioid peptides. In this study, Fos-like immunoreactivity (FLI) and i n situ hybridization of the three opioid mRNAs were used to examine th e effect of low (2 Hz) and high (100 Hz) frequency EA on neuronal acti vities and the expression of opioid genes. 2 Hz and 100 Hz EA induced a markedly different spatial patterns of Fos expression in the rat bra in, suggesting there are distinct neuronal pathways underlying EA of d ifferent frequencies. Likewise, 2 Hz and 100 Hz EA exert differential effects on opioid gene expression: while 2 Hz EA induced a more extens ive and intensive preproenkephalin (PPE) mRNA expression than 100 Hz E A, it had no effect on preprodynorphin (PPD) mRNA expression which was significantly increased by 100 Hz EA stimulation. In contrast, EA of both frequencies did not affect POMC mRNA expression.