Dopamine and alpha-endorphin are contained in different neurons of the arcuate nucleus of hypothalamus as revealed by combined fluorescence histochemistry and immunohistochemistry.

An attempt was made to demonstrate dopamine and alpha-endorphin neurons in the same sections of the arcuate nucleus by combining the techniques of fluorescence histochemistry and immunohistochemistry. Dopamine neurons were found mainly in the medial part near the wall of the third ventricle and alpha-endorphin neurons in the lateral part. We failed to detect any neurons showing simultaneous dopamine fluorescence and alpha-endorphin positive immunoreactivity. We conclude therefore that dopamine synthesizing neurons are probably different from alpha-endorphin synthesizing neurons in the arcuate nucleus.