[Effect of intrathecal katemine on the expression of nNOS in spinal dorsal horn in rats with formalin pain.]

Author(s): Yang Y, Guo QL, Zou WY, Wang E

Affiliation(s): Department of Anesthesiology,Xiangya Hospital,Central South University,Changsha 410008,China.

Publication date & source: 2006-10, Zhong Nan Da Xue Xue Bao Yi Xue Ban., 31(5):747-51.

Publication type:

ObjectiveTo investigate the expression of neuronal nitric oxide synthase (nNOS) in spinal dorsal horn and the effect of intrathecal katemine on the expression of nNOS in the rats with formalinjinduced pain. MethodsThirty-two Sprague-Dawley rats were randomly divided into 4 groups (n=8 in each group): a control group (C) ,an intrathecal saline group (NS) ,a katemine 50mug group (K1),and a katemine 100mug group (K2). The rats that were anesthetized with 10% chlroral hydrate 300~350mg/kg by abdominal injection were intrathecally inserted a microspinal catheter into the lumbar region according to the method of modified Yaksh . After 5 days ,the rats in Group NS,K1 and K2 were intrathecal 20muL saline or 10muL katemine (50,100mug) followed by 10muL saline,respectively. Thirty minutes later,5% formalin 50muL was subcutaneously injected into the left hindpaw. Pain intensity scoring (PIS) was used to assess antinociceptive behavior within 1h after the formalin injection. The expression of nNOS in the spinal dorsal horn of L5 segment was assayed using immunohistochemistry 24h later. ResultsCompared with Group NS,PIS of Group K1 and K2 was decreased obviously (P<0.01) in the second phase of formalin pain. The number of immunoreactive soma and immunohistochemistic dying grade of nNOS in the spinal dorsal horn of L5 segment was higher in Group NS than that in Group C (P<0.01),but Group K1 and K2 were lower than Group NS (P<0.01). ConclusionThere was significant antinociception of intrathecal katemine in rats with formalin pain.Intrathecal katemine significantly inhibited the increase of nNOS expression in the spinal dorsal horn of formalinjinduced pain,suggesting nNOS plays an important role in nociceptive transmission and modulation of the spinal cord.