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Papers of the Week

Papers: 20 Aug 2022 - 26 Aug 2022

2022 Aug 22

J Neurotrauma

The adverse effects of repeated, intravenous morphine on recovery following spinal cord injury in young, male rats are blocked by a kappa opioid receptor antagonist.


Immediately following spinal cord injury (SCI) patients experience pain, associated with injury to the spinal cord and nerves as well as accompanying peripheral injuries. This pain is usually treated with opioids, and most commonly with morphine. However, in a rodent model we have shown that, irrespective of the route of administration, morphine administered in the acute phase of SCI undermines long-term locomotor recovery. Our previous data suggests that activation of kappa opioid receptors (KORs) mediate these negative effects. Blocking KORs with nor-Binaltorphimine (norBNI), prior to a single dose of epidural morphine, prevented the morphine-induced attenuation of locomotor recovery. Because numerous cellular changes occur with chronic opioid administration compared to a single dose, the current study tested whether norBNI was also effective in a more clinically relevant paradigm of repeated, intravenous morphine administration after SCI. We hypothesized that blocking KOR activation during repeated, intravenous morphine administration would also protect recovery. Supporting this hypothesis, we found that blocking KOR activation in young, male rats prevented the negative effects of morphine on locomotor recovery, although neither norBNI nor morphine had an effect on long-term pain at the doses used. We also found that norBNI treatment blocked the adverse effects of morphine on lesion size. These data suggest that a KOR antagonist given in conjunction with morphine may provide a clinical strategy for effective analgesia without compromising locomotor recovery after SCI.