The underlying mechanism for electroacupuncture (EA) associated functional improvement in patients suffering from spinal cord injury (SCI) is largely unknown. Collateral sprouting is one plausible factor, where the cord microenvironment may contribute greatly. The present study evaluated the effects of EA on collateral sprouting from spared dorsal root ganglion (DRG), sensory functional restorations, and differential gene expressions in spinal cord after partial DRG removal in the rat. Following EA, N1 waveform latencies for cortical somatosensory evoked potential significantly shortened. The densities of terminal sprouting from the spared DRG significantly increased on the EA versus the non-EA side. Microarray analysis revealed that several genes were upregulated on the acupunctured side at different time points; they were ciliary neurotrophic factor (CNTF) at 1 day postoperation (dpo), fibroblast growth factor (FGF)-1, insulin-like growth factor (IGF) 1 receptor, neuropeptide Y, and FGF-13 at 7 dpo, and CNTF and calcitonin gene-related polypeptide-alpha at 14 dpo, respectively. Meanwhile, five genes (CNTF, p75-like apoptosis-inducing death domain protein, IGF-1, transforming growth factor-beta 2, and FGF-4) were downregulated at 7 dpo. Furthermore, reverse transcriptase polymerase chain reaction results supported the gene chip analysis. It was concluded that the EA induced sensory functional restorations following partial DRG ganglionectomies could be brought about by intraspinal sprouting from the spared DRG, as well as multiple differential gene expressions in the spinal cord. The results could have clinical application in EA treatment of patients after spinal injury.
In the present study, we investigated the role of endogenous neurotrophin-3 in nerve terminal sprouting 2 months after spinal cord dorsal root rhizotomy. The left L1–5 and L7–S2 dorsal root ganglia in adult cats were exposed and removed, preserving the L6 dorsal root ganglia. Neurotrophin-3 was mainly expressed in large neurons in the dorsal root ganglia and in some neurons in spinal lamina II. Two months after rhizotomy, the number of neurotrophin-3-positive neurons in the spared dorsal root ganglia and the density of neurite sprouts emerging from these ganglia were increased. Intraperitoneal injection of an antibody against neurotrophin-3 decreased the density of neurite sprouts. These findings suggest that endogenous neurotrophin-3 is involved in spinal cord plasticity and regeneration, and that it promotes axonal sprouting from the dorsal root ganglia after spinal cord dorsal root rhizotomy.
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