The Effect Of Partial Dorsal Root Rhizotomy And Acupuncture On The Expression Of GDNF And FGF-2 In Spared Dorsal Root Ganglia

Objective: To explore the temporal change on the expression of GDNF and FGF-2 in spared dorsal root ganglia after partial dorsal root rhizotomy and acupuncture. Method: The cats were divided into normal group, partial dorsal root rhizotomy group (L1-L5, L7-S2 was transected, L6 DRG was spared, animals surviving for 7 or 14 days after operation respectively) and partial dorsal root rhizotomy plus acupuncture group (Two groups Xuewei including Zusanli and Xuanzhong, Futu and Sanyinjiao located in distribution area of L6 spinal nerve in one side of hind limb were stimulated alternatively 30 minutes everyday). The partial dorsal root rhizotomy group and acupuncture group were sacrificed on day 7 or 14 and the L6 dorsal root ganglia was taken out in each animal and put into 4% polymerisatum for 12 hours and then 20% saccharose PBS over night. DRGs (L6) were made into frozen sections 20 m on the thickness respectively. Then, sections were stained under same condition using specific GDNF (1:500) and FGF-2 (1:500) antibody by ABC method. The GDNF and FGF-2 positive large, medium and small sized neurons in DRG were counted in each group. All data were analyzed by q test. Results: 1.GDNF immunoreactivity can be observed in both large sized and medial-small sized DRG neurons. The number of total positive neurons declined 7days after partial dorsal root rhizotomy, and still lesser after 14days. Interestingly, the tendency on the number of positive medial-small sized DRG neurons was just the same as that of total positive neurons, while positive large sized neurons keep no differences between 7l day and 14th day group, although the number also declined after operation. After acupuncture, the number of DRG total positive neurons and the positive medial-small sized DRG neurons come back tonormal horizon in both time points, while the number of positive large sized neurons was significantly lower than that of normal horizon and have no differences compared with that of partial dorsal root rhizotomy groups in both time points after acupuncture. 2. FGF-2 immunoreactivity can also be seen in both large sized and medial-small sized DRG neurons. After partial dorsal root rhizotomy, the number of total positive neurons declined in 7th day and come back to normal horizon in 14th day. The number of positive medial-small sized neurons also showed declination followed with inclination, just the same as that of total positive neurons, while the number of positive large sized neurons has no difference with normal group in two times. After acupuncture, the number of total positive neurons increased and come back to normal horizon in 7th day and much higher in 14th day than that of normal group, 14 days group after partial dorsal root rhizotomy and 7days group after acupuncture. The number of both positive large and medial-small sized neurons showed no differences in 7th day after acupuncture but significantly increased in 14th day compared with that of normal group. Conclusion: partial dorsal root rhizotomy can lead to continuously declination of total GDNF immunoreactive neurons in spared ganglia, till the 14th day, while acupuncture can reverse this tendency, and this reversion is related to the increase on the number of medial-small sized neurons. FGF-2 expression showed declination in 7th day, but coming back to normal horizon in 14th day after partial dorsal root rhizotomy. Acupuncture can significantly increased the number of total FGF-2 positive neurons compared with partial dorsal root rhizotomy and this increasing is relative to the expression of both large and medial-small sized neurons. Our results indicate that the expression change of GDNF and FGF-2 after partial dorsal root rhizotomy correlates with spinal cord plasticity and the increased expression of GDNF and FGF-2 play an important role during the process of acupuncture's promoting spinal cord plasticity.