Opioid and nonopioid mechanisms may contribute to dynorphin's pathophysiological actions in spinal cord injury
✍ Scribed by MD Alan I. Faden
- Book ID
- 102707491
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 830 KB
- Volume
- 27
- Category
- Article
- ISSN
- 0364-5134
No coin nor oath required. For personal study only.
✦ Synopsis
It has been suggested that the opioid dynorphin, an endogenous agonist for K-opiate receptors, contributes to secondary tissue damage after spinal cord injury. To evaluate this hypothesis further, effects of intrathecally administered dynorphin (Dyn) A-( 1-17), dynorphin antiserum, or the K-selective opiate antagonist nor-binaltorphimine (nor-BNI) were studied in rats subjected to standardized impact trauma to the thoracic spinal cord. Effects of intrathecal Dyn A- (1-17) were also compared to those of Dyn A-(2-17), which is inactive at opiate receptors, in uninjured and injured animals. Both Dyn A-(1-17) and Dyn A-(2-17) produced motor dysfunction in uninjured rats, but Dyn A-(1-17) was approximately 2.5 times more potent. At lower doses of Dyn A-(1-17), paraparesis was markedly attenuated by nor-BNI; nor-BNI was less effective at higher doses of Dyn A-( 1-17) and did not modify the motor dysfunction produced by Dyn A-(2-17). Treatment with dynorphin antiserum significantly improved outcome after trauma as compared to control treatment with normal rabbit serum or leucine-enkephalin antiserum. Dyn A-(1-17), but not Dyn A-(2-17) at similar doses, exacerbated neurological dysfunction after spinal cord injury. Pretreatment with nor-BNI attenuated neurological dysfunction after traumatic spinal cord injury to a similar degree in rats administered saline or Dyn A-(1-17). These observations support the hypothesis that dynorphin contributes to certain pathophysiological changes after traumatic spinal cord injury through both opiate-receptor (K-receptor)-mediated and nonopioid mechanisms.
Faden AI. Opioid and nonopioid mechanisms may contribute to dynorphin's pathophysiological actions in spinal cord injury.