NGF和BDNF在炎性痛大鼠背根神经节和脊髓背角的表达

目的 观察神经生长因子(NGF)和脑源性神经营养因子(BDNF)在福尔马林致痛大鼠外周、背根神经节(DRG)和脊髓背角的表达变化及相互关系，探讨神经营养因子在疼痛发生机制中的作用。方法 采用大鼠后足掌皮下注射福尔马林溶液的外周炎性痛模型。成年SD大鼠24只随机分为四组(每组6只)：对照组(A组)；致痛组根据取材时间不同分为，致痛后2h取材(B组)、致痛后24h取材(C组)、致痛后48h取材(D组)。观察致痛1h内疼痛行为变化，应用免疫组织化学方法结合计算机图像分析技术检测致炎足底皮肤、DRG和脊髓背角浅层内NGF的表达，及DRG和脊髓背角浅层表达BDNF的变化。结果 所有致痛组大鼠都表现出明显的两期伤害性反应。在致痛后2h患侧足底皮肤、DRG和24h时脊髓背角浅层表达的NGF开始增加，致痛24h后BDNF在患侧DRG表达开始增加，且与NGF在患侧DRG神经元的表达变化成正相关。48h时BDNF在患侧脊髓背角浅层表达开始增加。结论 NGF不仅是产生炎性痛外周机制的重要介质之一，还可通过促进BDNF在脊髓背角的表达，共同参与中枢敏感化的产生。

Expression of nerve growth factor and brain-derived neurotrophic factor in the dorsal root ganglion and the spinal dorsal horn following peripheral inflammatory hyperalgesia in rats

Objective To investigate the changes in the expression of nerve growth factor (NGF) and brain-derived neurotrophic (BDNF) in the dorsal root ganglion (DRG) and spinal dorsal horn following peripheral inflammatory hyperalgesia induced by formalin injected into the plantar region of the right hindpaw in rats. Methods Twenty-four adult SD rats weighing 250-400 g were studied. Peripheral inflammatory hyperalgesia was induced by an intraplantar injection of 5% formalin into right hindpaw. The animals were randomly divided into 4 groups (n=6 in each group), group A:control; group B:2 h after formalin injection; group C:24 h after formalin injection and group D: 48 h after formalin injection. Pain response was recorded. The expression of NGF and BDNF in the inflamed skin, DRG and spinal dorsal horn was detected using immuno-histochemistry technique and image analysis method. Results There were significant bi-phasic nociceptive responses induced by intraplantar injection of formalin in rats. The expression of NGF started to increase 2 h after injection, in the inflamed skin, ipsilateral DRG and dorsal horn neurons and reached the peak level at 24 h after injection. The expression of BDNF in ipsilateral DRG and dorsal horn neurons was unchanged 2 h after injection and started to increase at 24 h after injection. There was a positive correlateion between the expression of NGF and BDNF in ipsilateral DRG neurons.Conclusion NGF is not only an important transmitter in the peripheral mechanicsm of inflammatory pain but also involved in central sensitization through facilitating expression of BDNF in dorsal horn neurons.