OBJECTIVE: To investigate the effects of nerve root compression on dorsal root ganglia. METHODS: Following the method of Kawakami, 4/0 ribbon gut were applied around left L4-6 spinal nerve roots in 50 SD rats. Just 3 mm cranial to the dorsal root ganglia, the nerve roots were secured by two ligation node. The nerve roots of right side were as control. The L4-6 spinal cord was taken out 1, 2, 4, 8, 12 weeks after surgery, respectively. The activity of fluoride resistant acid phosphatase (FRAP) was determined by the enzyme histochemistry (Gomori method) and the image analysis technique. RESULTS: In the test side, the FRAP content of spinal dorsal horn reduced 4 weeks after operation. And there were gradually more and more decreases from 4 to 12 weeks. There was significant difference between the test side and control side (P lt; 0.01). CONCLUSION: Chronic nerve root compression causes damage to dorsal root ganglia.
Injury of dorsal root ganglia (DRG) may cause sensory and motor dysfunction. In order to investigate the changes of somato-sensory evoked potential (SEP) and histological characteristics of DRG in different causes and different periods of injury, fifty-two rabbits were chosed to build the models. The rabbits were divided into 4 groups: Control group (n = 4); mechanical compressing group (n = 16); inflammatory injury group (n = 16); and treatment group (2% lidocaine with hydroprednisone was administered locally, n = 16). After one to eight weeks, SEP was determined and samples of DRG were obtained to observe the histological and ultrastructural changes every week. The result showed that the gap junction of microvascular endothelium in DRG had been destroyed by the mechanical compression was the major cause of the vessel permeability increasing. The increasing of endothelial pinocytic vesicles transportation and widening of endothelial gap junction were the main causes of inflammatory irritation of DRG. The local infiltration with 2% lidocaine and hydroprednisone could obviously ameliorate inflammatory injury in DRG.
Abstract In case of sciatic nerve injury, there is degeneration of neuron in the corresponding segment of spinal cord. To study whether NGF could protect the dorsal root ganglia in this situation, the following experiments were performed: 72 SD mice were divided into 2 groups. In each mouse, the sciatic nerve was sectioned at the middle of the right thigh, and then,the proximal end of the sciatic nerve was inserted into a one ended silastic tube. The NGF 0.15ml (contain 2.5S NGF 0.15mg) was injected into the tubes of the experimental group, while a equal amount of normal saline was injected into the tubes of the control group. After 1, 3, 5, 9, 20 and 30 days, 6 mice of each groupwere sacrificed respectively, and 5th to 6th lumbar segments of the spinal cords were resected for examination. By histochemical study, the activity of fluoride resistant acid phosphatase (FRAP) of each animal was detected. The results showed: (1) Excision of the sciatic nerve led to decrease of FRAP activity, it suggested that the injury of sciatic nerve could damage the dorsal root ganglia; (2) The use of exogenous NGF could protect the FRAP activity. It was concluded that NGF played an important role in protecting the dorsal root ganglia in peripheral nerve injury, in vivo.
ObjectiveTo investigate the role of Wnt5a in the mechanism of radiculopathy and the relation between Wnt5a and tumor necrosis factorα(TNF-α) by observing the change of the expression of Wnt5a in the rat model of chronic compression of dorsal root ganglia (CCD). MethodsA total of 192 adult male Sprague Dawley rats were allocated into 4 groups: shame group (group A, n=48), CCD group (group B, n=48), CCD+sal ine group (group C, n=48), and CCD+etanercept group (group D, n=48). An L-shaped needle (about 3.5 mm in length, 0.6 mm in diameter) was inserted into the L5 intervertebral foramen, and the dorsal root ganglia (DRG) was compressed by the needle to prepare the CCD model in groups B, C, and D, and then normal sal ine (5.5 mg/kg) or etanercept was injected intraperitoneally in groups C and D. The intervertebral foramen was exposed in group A. The mechanical pain threshold of the posterior paw was tested by the von Frey filaments at 1, 3, 5, and 7 days after operation; the expressions of Wnt5a protein and mRNA were detected at 3 and 7 days after operation by immunohistochemical staining and RT-PCR, respectively. ResultsThe mechanical pain threshold of groups B and C was significantly lower than that of groups A and D, and in group D than in group A (P < 0.05), but no significant difference was found between groups B and C (P > 0.05). The Wnt5a positive cells and the mRNA expression of Wnt5a at 7 days were significantly more than those at 3 days in groups B, C, and D (P < 0.05). The Wnt5a positive cells and the mRNA expression of Wnt5a in groups B and C were significantly more than in groups A and D, and in group D than in group A (P < 0.05), but no significant difference was shown between groups B and C (P > 0.05). ConclusionThe expression of Wnt5a in the DRG is increased after CCD. The expression of Wnt5a in the DRG is decreased after the administration of the inhibitor of TNF-α.