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 pain. A multiple pathway system might help explain the conflicting effects of dynorphin in the CNS [3].