| Objective: To explore the expression of TGF β 1 and GDNF in adult rat's spinal cord after complete transection.Method: 50 SD adult rats were randomly divided into 5 groups: normal control group, SCT (spinal cord was completely transected between T9-T10 segments) 3d, 7d, 14d and 21d group. BBB (Basso, Beattie, Bresnahan) score, SEP (somatosensory evoked potential) technique were adopted to assess the locomotor and sensory functional revival of animals for 1d, 3d, 7d, 14d and 21d post operation (dpo).Spinal cord segments of five rats in each group were used for immunohistochemical SP staining with anti-TGFβ 1 antibody and anti-GDNF antibody. The other five aninmal's spinal cord was used for Western blotting analysis. Localization and staining level of TGF β 1, GDNF immunorectivities in spinal cord were observed under microscope. Densitometric analysis was performed using Bio-Gel Imagining system equipped with Genius synaptic gene tool software. Datas were analyzed by one-way ANOVA and LSD-q test.Results: BBB score for the locomotor function of the hindlimbs was 0 post operation. Till 21dpo, it was 1.17±0.11. After injury, SEP was not recorded. In spinal cord of control group, TGFβ 1-like immunoproduct was observed in the cytoplasm of motoneurons in ventral horn, glial cells of white matter. For rostrol part, TGF β 1 immunoreactive of neurons in the ventral horn increased at 7dpo and reached a peak at 21dpo. For caudal part, TGF β 1-like immunoreactive of positive neurons increased at 3dpo post injury and reached a peak at 21dpo.The immunoreactivity level of astrocytes did not increase until 14dpo and reached it's peak at 21dpo. TGF 3 1 protein level was decreased after injury in rostrol part, then began to revert at 21dpo. In caudal part, no distinct change in TGF 3 1 protein level was observed post operation. But TGF 3 1 protein level was increased evidently at 21dpo. GDNF-like immunoproduct was observed in motor neurons of ventral horn, neurons of intermediate zone, sensory neurons of dorsal horn and neural glial cells in white matter of control group. Immunoproducts were distributed in nucli and cytoplasm of neurons. For rostrol part, the staining level distinctly increased at 3dpo and reached a peak at 7dpo, then declined slightly. The immunoreactivity of neural glial cells in white matter increased at 3dpo and continuously increased till 21dpo. But in caudal part, the immnoreactivity of GDNF slightly increased after operation, and then slightly declined at 21dpo. The immunoreactivity of astrocytes in white matter did not increase until 14dpo. From 3dpo, the immunoreactivities were observed only in cytoplasm of part neurons in rostrol and caudal segment, but both in cytoplasm and nuclei at 21dpo. Western blotting analysis showed that the level of GDNF protein in rostrol part slightly increased at 3dpo, then declined distinctly at 7dpo. Till 14dpo, it increased again and reached a peak at 21dpo. In caudal part, the level of GDNF protein decreased to the lowest extent at 7 dpo and increased at 14dpo.Conclusion: After spinal cord transection, the sensory and locomotor function did not revive in 21d post operation. The expression of TGF 3 1 and GDNF changed with different cells, different part and different period in the spinal cord following SCT. In the first stage after SCT, the expression of TGF 3 1 in the rostrol segments was extremely downregulated. In the latter stage after SCT, the expression of TGF 3 1 in the caudal segments was notably up-regulated. After SCT, the change of TGF 3 1 immunoreactivty in neural glial cells of white matter in spinal cord was consistent with that of TGF 3 1 protein level. It suggested that the neural glial cells might play a role in the endogenous regeneration by synthesizeing TGF 3 1 protein after SCI, but the role was not unconspicuous in the first stage after SCT. In the latter stage after SCT, this role was gradually increased. The expression of GDNF protein in the rostrol segments wastransitorily upregulated in the first stage after SCT, down-regulated at 7dpo, then returned to normal level at 21dpo. In caudal segments, the expression of GDNF was slowly increased in the latter stage after SCT. The immunoreactivity of GDNF was enhanced both in neurons and glial cells, but the immunoreactivity of GDNF in rostrol part was more evident than that in caudal segments. It suggested that rostrol part of injuried spinal cord itself could play a protective role by upregulating endogenous GDNF. In caudal part, the expression of endogenous GDNF was decreased and delayed because of serious spinal cord injury. |
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