Immunohistochemical evidence for subpopulations of dynorphinergic neurons

Biochemical studies have shown that the dynorphin precursor can generate at least seven opioid peptides. We report here a study of dynorphin products analyzed on adjacent semithin sections of rat brain, showing evidence for differential peptide localization among magnocellular neurons. In the oxytocinergic nucleus of the anterior commissure, staining was strong for dynorphin B but very weak for other prodynorphin markers; in the supraoptic nucleus, a discrete subset of dynorphin neurons were positive for leu-enkephalin.