Dynamic changes in the levels of striatal proenkephalin mRNA and large molecular weight enkephalin containing...

Electroacupuncture has been shown to increase met- and leu-enkephalin contents in rat striatum and hypothalamus. Its mechanism was further studied by measuring the levels of the large molecular weight enkephalin containing peptides (LECP), processed intermediates, free leu-enkephalin as well as proenkephalin mRNA in the striatum of rats decapitated at different times after the termination of 30 min electroacupuncture. A prominent increase of leu-enkephalin was seen in rats decapitated immediately after electroacupuncture. This increase returned to control level at 0.5 h. The levels of LECP and intermediates began to elevate at 1 h after electroacupuncture, reached a plateau at 8 h and lasted for 96 h. A second phase of smaller but longer lasting increase of leu-enkephalin appeared at 8-96 h. The proenkephalin mRNA amount measured by dot-blot procedure increased 3-5 folds starting at 1 h and lasting for at least 48 h.