Chudler Eric H, Anderson Leigh C, Byers Margaret R
Department of Anesthesiology, Box 356540, University of Washington, Seattle, WA 98195-6540, USA Department of Oral Biology, University of Washington, Seattle, WA 98195, USA Department of Biological Structure, University of Washington, Seattle, WA 98195, USA.
Pain. 1997 Nov;73(2):141-149. doi: 10.1016/S0304-3959(97)00088-2.
Nerve injury to the mandibular division of the trigeminal nerve has been shown to cause satellite cell reactions that extend beyond the mandibular division of the trigeminal ganglion into the maxillary and ophthalmic divisions. The goal of this study was to determine whether any physiological abnormalities correlated with this dispersal of satellite cell reaction. We investigated the electrophysiological and satellite cell glial fibrillary acidic protein immunoreactivity (GFAP-IR) changes that occur within the trigeminal ganglion 3, 10 and 59 days after a crush injury of the inferior alveolar nerve (IAN). At 3 days after IAN crush, there were no mechanically-evoked responses to ipsilateral stimulation of the skin and intraoral structures (e.g., mandibular incisor, lower lip and rostral mandibular gingiva) innervated by the IAN. However, the peripheral representations of the auriculotemporal, mylohyoid, lingual and maxillary nerve were intact and no abnormal responses to mechanical stimulation were detected to stimulation of tissue innervated by these nerves. By 10 days after the IAN crush, mandibular neurons responded to mechanical and electrical stimuli of the peripheral receptive field of the IAN, but with slower conduction velocities and higher electrical thresholds compared to control values. These abnormal electrophysiological response characteristics persisted 59 days following nerve injury. At 3, 10 and 59 days after IAN crush, 3-4% of the recorded mandibular neurons displayed spontaneous activity that was never observed in rats without nerve injury. Spontaneous activity was also never observed in neurons recorded in the maxillary or ophthalmic divisions of the trigeminal ganglion. Intense GFAP-IR in satellite cells was observed surrounding a mean of 131.7 neurons/section within the mandibular division of the trigeminal ganglion 3 days after nerve injury and around 50.3 neurons/section at 10 days. GFAP-IR was also present surrounding 16.5 and 10.3 neurons/section in the maxillary division of the trigeminal nerve at 3 and 10 days, respectively. At 59 days after IAN crush, GFAP-IR satellite cells were found around 22.9 neurons/section in the mandibular division of the trigeminal nerve, but were not found elsewhere in the trigeminal ganglion. The more extensive distribution of neurons encircled by satellite cell GFAP-IR compared to the trigeminal ganglion region containing abnormal electrophysiological responses demonstrates that abnormal neuronal signaling may not be characteristic of trigeminal ganglion neurons that are surrounded by GFAP injury reactions. However, the persistence of GFAP-IR 59 days after nerve injury suggests that satellite cell GFAP is involved in the long-term recovery of injured neurons.
已证明，三叉神经下颌支的神经损伤会导致卫星细胞反应，这种反应会超出三叉神经节的下颌支，延伸至上颌支和眼支。本研究的目的是确定是否有任何生理异常与卫星细胞反应的这种扩散相关。我们研究了下牙槽神经（IAN）挤压伤后3天、10天和59天三叉神经节内发生的电生理变化以及卫星细胞胶质纤维酸性蛋白免疫反应性（GFAP-IR）变化。IAN挤压伤后3天，对IAN支配的同侧皮肤和口腔内结构（如下颌切牙、下唇和下颌牙龈前部）进行刺激时，未出现机械诱发反应。然而，耳颞神经、下颌舌骨肌神经、舌神经和上颌神经的外周代表区完好无损，对这些神经支配的组织进行刺激时，未检测到对机械刺激的异常反应。IAN挤压伤后10天，下颌神经元对IAN外周感受野的机械和电刺激有反应，但与对照值相比，传导速度较慢且电阈值较高。这些异常的电生理反应特征在神经损伤后59天持续存在。IAN挤压伤后3天、10天和59天，记录到的下颌神经元中有3%-4%表现出自发活动，这在未损伤神经的大鼠中从未观察到。在三叉神经节的上颌支或眼支记录的神经元中也从未观察到自发活动。神经损伤后3天，在三叉神经节下颌支内，平均每个切片有131.7个神经元周围观察到卫星细胞强烈的GFAP-IR，10天时约为50.3个神经元/切片。在三叉神经上颌支中，3天和10天时分别有16.5个和10.3个神经元/切片周围存在GFAP-IR。IAN挤压伤后59天，在三叉神经节下颌支内，约22.9个神经元/切片周围发现有GFAP-IR卫星细胞，但在三叉神经节的其他部位未发现。与含有异常电生理反应的三叉神经节区域相比，卫星细胞GFAP-IR环绕的神经元分布更广泛，这表明异常神经元信号可能不是被GFAP损伤反应包围的三叉神经节神经元的特征。然而，神经损伤后59天GFAP-IR仍持续存在，这表明卫星细胞GFAP参与了受损神经元的长期恢复。
