MD altered Dyn-A peptide and KOR expression in the LHb. A. Example images of non-MD (left) and MD (right) immunolabeling for LHb neurons (NeuN, red, top), Dyn-A(1–8) peptide (green, middle) and merged overlay images (bottom panel). Scale bar = 50 μm. MD significantly increased average LHb Dyn-A density compared to non-MD controls B. LHb of MD rats had significantly lower abundance of opioid peptide receptor, kappa 1 (oprk1) mRNA expression compared to non-MD controls. **p < 0.01. (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)