Effects of electro-acupuncture on CNTF expression in spared dorsal root ganglion and the associated spinal lamina II and nucleus dorsalis following adjacent dorsal root ganglionectomies in cats

It is well known that plasticity occurs in deafferented spinal cord, and that electro-acupuncture (EA) could promote functional restoration. The underlying mechanism is, however, unknown. Ciliary neurotrophic factor (CNTF) plays a crucial role in neurite outgrowth and neuronal survival both in vivo and in vitro, and its expression might explain some of the mechanism. In this study, we investigated the effects of EA on CNTF expression in the spared L6 dorsal root ganglion (DRG), and spinal lamina II at spinal segments L3 and L6 as well as nucleus dorsalis (ND) of L3 spinal segment following removal of L1–L5 and L7–S2 (DRG) in the cat. After ganglionectomies, the total and small-to-medium-sized numbers of immunoreactive neurons decreased at 3 dpo, and returned to the sham-operated level as early as 7 dpo. After EA, immunoreactive neurons in L6 DRG noticeably increased at 7 dpo, compared with the non-acupunctured group. Notable increase in the large neurons was seen at 14 dpo, while their numbers in L3 and L6 spinal cord segments significantly declined at 3 dpo. Those in L3 segment did not reach the sham-operated level until 14 dpo, but their numbers in L6 segment returned to the sham-operated level as early as 7 dpo. CNTF immunopositive neurons in the ND of L3 segment returned to the sham-operated level at 14 dpo. After EA, their number significantly increased as early as 7 dpo in lamina II of L6 segment, and as late as 14 dpo in ND of L3 segment. Western blot analysis showed CNTF changes corresponding to those shown in immunohistochemical staining. It is concluded that CNTF expression was involved in the EA promoted plastic changes in L6 DRG and the associated deafferented spinal lamina and ND.