Effects of special CaMKⅡ inhibitor m-AIP on sensory-discriminative and affective-motivational pain responses in chronic constriction injury of sciatic nerve rats / 中华行为医学与脑科学杂志

ABSTRACT

Objective To investigate the sensory-discriminative and affective-motivational pain response of intrathecal injection of m-AIP,a special inhibitor of CaMKII,in a rat model of chronic constriction injury of sciatic nerve(CCI).Methods Eighteen SD rats were divided randomly into 3 groups(n=6)Group S(sham),Group C(control) and Group m-AIP.Group C and m-AIP were operated with the model of neumpathic pain induced by chronic constriction injury of sciatic nerve; Group S were treated as sham operated rats.Seven days after operation,Group S and C received intrathecal injection of 0.9％ NaCI 20 μl,while Group m-AIP received intrathecal injection of m-AIP 0.5 nmol/20 μl.Escape/avoidance behavior refrecting the affective-motivational dimension of pain was measured on 1.5 h after administration.Rats received pain behavior tests including paw withdrawal mechanical threshold(PWMT) and paw withdrawal thermal latency(PWTL) before and 2 h,4 h,8 h after administration.Results Treatment with m-AIP attenuated escape/avoidance behavior and reversed pain behaviors after CCI.At 2h and 4h after administration,Group m-AIP PWTL((1 1.45 ± 2.04)s,(10.26 ± 1.48)s) and PWMT ((21.15 ±4.32)g,(20.45 ±4.09) g) were increased when compared with Group C PWTL((9.63 ± 1.65)s,(9.30 ±0.73)s),PWMT((13.87 ±2.36)g,(14.80 ±3.12)g)(P＜0.05).Before and8 h after administration,Group m-AIP PWTL,PWMT had no significant difference when compared with Group C (P ＞ 0.05).Conclusion CaMKⅡ may play an important role in sensory and affective pain processing in neuropathic rats.Intrathecal injection of m-AIP can effectively improve pain behaviors and attenuate negative affect.