Effect Of Lappaconitione On Fos-protein, Nitric Oxide Synthase And Substance P Of Spinal Cord In Incision-induced Rats

Objective: To study whether or not lappaconitine suppressed spinal sensitization in the rat incision model and to discuss the possible mechanism.Method: 28 awake rats were invided into 6,6,8,8 four groups, the first two of which were peritoinjectecd saline vehicle and lappaconitine 4mg/kg respectively, the third of which received incision in the plantar of the right hindpaw and the fouth of which was peritoinjected saline vehicle 16 min prior to the same incision. 56 awake rats were meanly divided into 7 groups that also received incision in the same region. To test the dose-dependent manner, the three of the groups received lappaconitine (1, 2, 4mg/kg ip) 16 min prior to the incisions. To test the preemptive analgesic effect of lappaconitine, a postincision group was set which lappaconitine (4mg /kg) was administered 16 min after the incision. To test the analgesic effct of lappaconitine involving the NE, a DDC group was set which DDC (200mg/kg) was administered 2 hours earlier, then the rats of the group received lappaconitine 4mg/kg 16 min prior to the incision. To test the local anesthesia of the lappaconitine, a pair of groups were set, one of which lappaconitine was injected in the right hindpaw and the other of which saline vehicle was injected in the same region.In the behavioral study, stepping behavior was evaluated 0-60 min after hindpaw incision. One and a half hour later, rats were killed and perfused, L4-S1 sections of spinal cords were dissected, sliced by freezing and processed by immunostained with a rabbit polyclonal antiserum directed against c-fos and SP, then the changes of FLI and PLI positive neurons in the dorsal horn were studied, also processed by NADPH-d histochemistry and the changes of NOS in the dorsal horn were aiso studied.Result:Incision-induced FLI positive neurons were mainly located in the superficial dorsal horn(laminaeⅠandⅡ)ipsilateral to the incision. Lappaconitine treatment markedly reduced incision-evoked nociceptive behavior and decreased the numbers of FLI ,NOS and SP positive neurons of dorsal horn in a dose-dependent manner. Compared to the control group, the differences were significant among the different dose group (P<0.05). The analgesic effect of lappaconitine preincision is superior to lappaconitine postincision both in behavioral experiments and spinal Fos protein and NOS suppression(P<0.01).⑶The analgesic effect of the group which DDC was administerd 2 hour earlier is inferior to the group of 4mg/ kg lappaconitine preincision both in behavioral experiments and spinal Fos protein, NOS and SP suppression(P<0.01).⑷The analgesic effect of the local injection of lappaconitine is superior to the local injection of saline vehicle both in behavioral experiment and spinal Fos protein, NO and SP suppression (P<0.01).Conclusion: ⑴The incision-evoked nociceptive behaviors and Fos, NOS and SP expression were suppressed by lappaconitine administration in dose-dependent manner.⑵The analgesic effect of lappaconitine given before pain stimulation was better than that give n after incision.⑶Lappaconitine enhanced the activity of brainstem descending pain modulation system and inhibited the inputs of peripheral pain message at spinal cord level through NE.⑷Lappaconitine also has the local anesthesia effect.