Influence of electroacupuncture of "Dazhui"（GV14） and "Mingmen" （GV4） on expressions of NL1 and NF-200 in spinal cord injury rats

Abstract

To observe the effect of electroacupuncture(EA) on activities of A2 type astrocytes(A2s)and A1 type astrocytes (A1s) , expressions of neurofilament protein 200 (NF-200, a marker of axon regeneration), nexin 1(NL1, a marker of synaptic regeneration), and regeneration of Nissl bodies in rats with spinal cord injury (SCI), so as to explore its mechanisms underlying improvement of SCI. A total of 75 male SD rats were rando-mized into sham operation, model, antibody neutralizing (AN), EA and EA+AN groups, with 15 rats in each group. The SCI model was established by using an infinite field impactor to deliver an about 200 k dyne weight onto the exposed spinal cord after making a dorsal laminectomy at vertebral level T10. EA (2 Hz, 1 mA) was applied to"Dazhui"(GV14) and "Mingmen"(GV4) for 20 min, once daily for 28 days. After modeling, intraspinal injection of neutralizing antibodies IL-1α, TNF-α and complement 1q (C1q, 2 μL) to the injured spinal locus for inhibition of A1 type astrocytes (A1s) was conducted on the 1st, 7th , 14th and 21st day for rats of AN and EA+AN groups. BBB rating scale was used to evaluate hindlimb locomotor function on day 1, 7, 14, 21 and 28 after modeling. The activation of A2s (its specific marker S100a10), astrocyte (its specific marker glial fibrillary acidic protein, GFAP), and A1s (its specific marker C3) in the spinal cord was detected by immunofluorescence, and the protein expressions of NF-200 and NL1 in the spinal cord detected by Western blot and immunohistochemistry, separately, and the neuronal regeneration was observed after Nissl staining. After SCI, the BBB scores at 1 , 7, 14, 21 and 28 day, and the immunoactivity of NL1 and NF-200 were significantly decreased (P<0.01), and the fluorescence intensity of double labelled S100a10 (A2s)/GFAP and C3, and the expression of NF-200 were considerably increased in the model group (P<0.05, P<0.01). In contrast to the model group, the BBB scores at 7, 14, 21 and 28 day, and the immunoactivity of NL1 and NF-200, and the fluorescence intensity of A2s/GFAP in the AN, EA and AN+EA groups, and the expressions of NL1 in the EA and AN+EA groups, and expression of NF-200 protein in the AN+EA group were evidently increased (P<0.05, P<0.01), and the fluorescence intensity of C3 was strikingly decreased in the EA group (P<0.01). The effect of AN+EA was significantly superior to that of single AN and EA in increasing BBB scores at 14, 21 and 28 day, and in up-regulating the immunoactivity of NF-200(P<0.01, P<0.05). Nissl staining showed damaged structure of the gray matter of the spinal cord, atrophy of the Nissl body, and pyknosis of neurons, which was milder in the AN and EA groups, particularly in the AN+EA group. EA at GV14 and GV4 may promote activation of A2s and promote regeneration of axons and synapses in SCI model rats.