Modifications in the distribution of met-enkephalin in the limbic system of the cat brain after electroacupuncture. An immunocytochemical study.

The distribution of met-enkephalin in the limbic system of the cat brain and its modification after low frequency electroacupuncture (EA) stimulation have been studied experimentally using the indirect immunocytochemistry technique. A marked increase of post-stimulation met-enkephalin immunoreactivity was observed in the tractus habenulo-penduncularis, tractus mamilo-thalamicus, and medial forebrain bundle, and a decrease at the level of the nucleus interpeduncularis, medialis dorsalis, stria terminals, septalis lateralis, septalis medialis, accumbens septi, supraopticus, and amygdaloideus centralis. The experimental results link the changes in immunoreactivity (and therefore the structures in which they take place) with the action of low frequency EA, and permit the conclusion that the met-enkephalinergic portion of the limbic system studied is directly related morpho-functionally with analgesia and the anatomic pathways of pain.