Experimental Study Of Peripheral Electrical Stimulation Participating In The Inhibition Of Chronic Central Pain Following Spinal Cord Injury

Objective (1)To investigate the expression of NR-1 subunit in the spinal dorsal horn of CCP rats according to erect CCP rat model following SCI with associativity and repetitiveness; (2)To study the effect of PES on CCP after enforcing PES on CCP rats; (3)To investigate whether opioid receptor inhibit CCP following SCI or not according to giving subcutaneous injections of Naloxone to the CCP rats with PES management.Methods The study included three parts. The first part: To erect CCP rat model following SCI with Allens weight-dropping method.The appropriate spinal segment was attacked by self-making appliance to cause contusion of spinal, the spontaneous pain behavior of CCP rats (mainly including autophagia, scratching, et al) was observed and the paw withdrawl threshold (PWPT) and the paw withdrawl latency (PWL) were assessed to judge whether CCP model or not. The second part: To measured the change of expression of NR-1 subunit in the spinal dorsal horn of CCP rats and the effect of PES on the expression of NR-1 subunit. 36 male SD rats were randomly divided into 3 groups(n=12): group without inserting stainless needles (group A); group with only inserting stainless needles in the proper acupoint (group B); group with inserting stainless needles and giving PES in the proper acupoint (group C); in addition, choosing randomly 12 normal SD rats as control group (group D).The PWPT and PWL changes were assessed in order to observe the cumulative effect of repeated PES or not after rats were given PES once every 4 days for 10 sessions. The third part: To observe the effect of Naloxone on CCP following SCI. 32 male SD rats were randomly divided into 4 groups (n=8):group with PES and giving subcutaneous injections of Naloxone(group X1); group with PES and giving subcutaneous normal saline(group X2); group with only inserting stainless needles and giving subcutaneous injections of Naloxone(group X3); group with only inserting stainless needles and giving subcutaneous injections of normal saline(group X4). The PWPT and PWL changes were assessed after 24h. Results (1)As compared with group A and group B,PWPT and PWL in group C were dramatically increased and the expression of NR-1 subunit was depressed obviously(P<0.01); PWPT, PWL and the expression of NR-1 subunit had no significant changes between group A and group B (P>0.05); As compared with group D, PWPT and PWL were depressed and the expression of NR-1 subunit was increased significantly (P<0.01); PWPT, PWL and the expression of NR-1 subunit had no significant changes between group C and group D. (2) As compared with group other three groups, PWPT and PWL were dramatically increased in group X2 (P<0.01); There was no significant change in group X1(P>0.05); PWPT and PWL showed no significant change in group X3 and group X4(P>0.05).Conclusions (1)The expression of NR-1 subunit was enhanced in the spinal dorsal horn of CCP rats following SCI; PES may inhibit CCP according to degrading the expression of NR-1 subunit; (2) PES may inhibit CCP following SCI via activation of endogenous opioid receptors.