Dynorphins are a class of opioid peptides that arise from the precursor protein prodynorphin. When prodynorphin is cleaved during processing by proprotein convertase 2 (PC2), multiple active peptides are released: dynorphin A, dynorphin B, and α/β-neo-endorphin¹. Depolarization of a neuron containing prodynorphin stimulates PC2 processing, which occurs within synaptic vesicles in the presynaptic terminal². Dynorphin is produced in many different parts of the brain, including the hypothalamus, the striatum, the hippocampus and the spinal cord. Dynorphin has been shown to be a modulator of pain response. injecting dynorphin into the subarachnoid space of the rat spinal cord produced dose-dependent analgesia that was measured by tail-flick latency. Analgesia was partially eliminated by opioid antagonist naloxone. dynorphin activates bradykinin receptors, which triggers the release of calcium ions into the cell through voltage-sensitive channels in the cell membrane. Blocking bradykinin receptors in the lumbar region of the spinal cord reversed persistent pain³. A multiple pathway system might help explain the conflicting effects of dynorphin in the CNS.

References:
1. Day R, Lazure C, Basak A, Boudreault A, Limperis P, Dong W, Lindberg I (January 1998). "Prodynorphin processing by proprotein convertase 2. Cleavage at single basic residues and enhanced processing in the presence of carboxypeptidase activity". J. Biol. Chem. 273 (2): 829–36.
2. Yakovleva T, Bazov I, Cebers G, Marinova Z, Hara Y, Ahmed A, Vlaskovska M, Johansson B, Hochgeschwender U, Singh IN, Bruce-Keller AJ, Hurd YL, Kaneko T, Terenius L, Ekstrom TJ, Hauser KF, Pickel VM, Bakalkin G (October 2006). "Prodynorphin storage and processing in axon terminals and dendrites". FASEB J. 20 (12): 2124–6.