Abstract:

Objective：To establish the rat model of depressive state complicated with insomnia caused by neuropathic pain， and to clarify the effect of chronic constrict injury（CCI） on the mood and sleep-wake behaviors of the rats. Methods Sixteen male SD rats were divided into sham operation group （n=8） and CCI group （n=8）， respectively. In CCI group， 4-0 silk thread was used to ligate the right sciatic nerve trunk of the rats， and the intensity was to maintain the blood supply of the sciatic nerve adventitia. In sham operation group， the sciatic nerve trunk of the rats was exposed and separated without ligation. The paw withdraw mechanical threshold （PWMT） of rats in two groups was measured weekly after operation to evaluate the pain threshold changes. Sucrose preference test was used to detect the percentages of sucrose preference of rats in two groups； tail suspension test was used to detect the immobility time in tail suspension of rats in two groups；open field test was used to detect the total distance of horizontal movement of rats in two groups；whether or not the depression-like behaviors of the rats existed were assessed；the implantable electro encepha logram/myoelectricity was used to analyze the sleep-wake behaviors of the rats. Results Compared with sham operation group， during 1－4 weeks after modeling， the PWMT and the percentage of sucrose preference of the rats in CCI group were significantly decreased（P<0.01）， the immobility time in tail suspension of the rats was increased （P<0.01）， and the total distance of horizontal movement of the rats was decreased （P<0.01）. Compared with sham operation group，during 2－4 weeks after modeling，the subjective night wake amount of the rats in model group was increased significantly （P<0.01），the non-rapid eye movement （NREM） sleep amount was decreased （P<0.01）， and the rapid eye movement （REM） sleep amount was increased （P<0.05 or P<0.01）.Compared with sham operation group，the subjective night cumulative amount of sleep-wake states and the REM sleep cumulative amount of the rats in CCI group were increased （P<0.05 or P<0.01），and the NREM sleep cumulative amount was decreased（P<0.01）. Conclusion The CCI rats have the depressive state complicated with insomnia，and these symptoms show a chronic trend and persist until the 4th week after modeling； this model can be used for observation of long-term effect and studying of related mechanism of the depressive state comlicated with insomia.

Key words: Neuropathic pain, Insomnia, Depression, Disease model，animal