Abstract
Background
Cyclooxygenase enzymes (COX) 1 and COX‐2 are important targets for pain relief after surgery, but the spinal contribution of both isoforms is still unclear, e.g., from a developmental point of view. Here we studied changes of spinal COX‐1 and COX‐2 expression and their functional relevance in rats of different ages for pain‐related behavior after incision.
Methods
Mechanical paw withdrawal thresholds (PWT) were assessed before and after incision and after intrathecal administration (IT) of SC‐560 (COX‐1 inhibitor) or NS‐398 (COX‐2 inhibitor) in rats aged 5, 14 and 28 days (P5, P14, P28). Furthermore, spinal expressions of COX proteins and m‐RNA were investigated.
Results
In P5 rats, only IT‐administered NS‐398 but not SC‐560 significantly reversed the decreased PWT after incision. In P14 rats, none of the substance modified PWT, and in P28 rats, only SC‐560 increased PWT. Spinal COX‐2 mRNA and protein were increased in P5 but not in P14 and P28 rats after incision. Whereas COX‐2 is located in spinal neurons, COX‐1 is mainly found in spinal microglia cells.
Conclusion
Our results demonstrate a possible developmental transition from COX‐2 to COX‐1 activation. Whereas in adult rats spinal COX‐1 but not COX‐2 is involved in pain‐related behavior after incision, it seems opposite in P5 rats. Interestingly, in P14, neither COX‐1 nor COX‐2 seems to play a role. This switch may relate to altered neuronal/microglia activation. Our findings indicate specific mechanisms to pain after incision that are age‐dependent and may guide further research improving pediatric pain management.
from Wiley: European Journal of Pain: Table of Contents https://ift.tt/2nqL0RI
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