NON-MYELIN-FORMING SCHWANN-CELLS PROLIFERATE RAPIDLY DURING WALLERIAN DEGENERATION IN THE RAT SCIATIC-NERVE
NON-MYELIN-FORMING SCHWANN-CELLS PROLIFERATE RAPIDLY DURING WALLERIAN DEGENERATION IN THE RAT SCIATIC-NERVE
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DOI：
10.1007/bf01206661
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发表时间：
1989-04-01
期刊：
影响因子：
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通讯作者：
JESSEN, KR
中科院分区：
文献类型：
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作者：
CLEMENCE, A;MIRSKY, R;JESSEN, KR
混合周围神经切断可导致远端轴突变性和髓鞘破坏。这些事件伴随着雪旺细胞急剧但短暂的增殖。本研究试图确定在这些条件下，形成髓鞘的和非形成髓鞘的雪旺细胞是否都进入增殖期，或者分裂细胞是否主要是从一个或另一个雪旺细胞群体中招募来的。由于巨噬细胞是变性周围神经中雪旺细胞有丝分裂原的重要来源，巨噬细胞在远端断端的巨噬细胞募集也被计时和定量。[~3H]-胸腺嘧啶核苷掺入和放射自显影作为细胞增殖的指标，细胞类型标记物和免疫组织化学用于鉴定髓鞘形成和非髓鞘形成的雪旺细胞。于横断后不同时间从大鼠坐骨神经和交感神经干远端取出细胞，培养24 h后测定细胞增殖情况。结果发现，在含有有髓和无髓纤维的坐骨神经中，髓鞘形成细胞和非髓鞘形成细胞(Po细胞)在术后第2天都显示[~3H]-胸腺嘧啶核苷标记指数显著升高，这两类细胞的幅度相似。PO+细胞和Po-细胞的增殖率在横断后8天仍保持较高水平。在大部分无髓交感神经干中，Po-Schwann细胞分裂的峰值不到Po细胞峰值的一半，到术后第4天，细胞分裂下降到仅略高于对照水平。在坐骨神经中，经单抗ED1鉴定的巨噬细胞数量在术后第1天急剧增加，并在第2天达到高峰。这些结果提供了有力的证据，表明非髓鞘形成的雪旺细胞和形成髓鞘的雪旺细胞在大鼠坐骨神经远端残端最初出现的雪旺细胞增殖几乎是同等的。他们还表明，在含有许多有髓纤维的神经中，非髓鞘形成细胞的增殖反应比基本上无髓神经中的增殖反应要大得多。巨噬细胞在坐骨神经中募集的时间与巨噬细胞是神经变性过程中雪旺细胞有丝分裂原的重要来源的假设一致。
Transection of a mixed peripheral nerve results in the degeneration of axons and breakdown of myelin in the distal stump. These events are accompanied by a sharp but transient Schwann cell proliferation. The present study seeks to determine whether both myelin-forming and non-myelin-forming Schwann cells enter a proliferative phase under these conditions, or whether the dividing cells are chiefly recruited from one or other of the Schwann cell populations. The macrophage recruitment into the transected distal stumps has also been timed and quantitated, since it has been suggested that macrophages are an important source of Schwann cell mitogens in degenerating peripheral nerves. Incorporation of [3H]-thymidine and autoradiography was used as a measure of cell proliferation, and cell type markers and immunohistochemistry were used to identify myelin-forming and non-myelin-forming Schwann cells. The cells were removed from the distal stump of the rat sciatic nerve and sympathetic trunk at various times after transection and proliferation measured during the first 24 h in culture. It ws found that in the sciatic nerve, which contains a mixture of myelinated and unmyelinated fibres, both myelin-forming cells, identified by presence of the myelin protein Po, and non-myelin-forming cells (Po- cells) showed a substantial elevation in [3H]-thymidine labelling index at day 2 postoperatively, which was similar in magnitude for the two categories of cell. The proliferation rate of both Po+ and Po- cells remained elevated for up to 8 days after transection. In the largely unmyelinated sympathetic trunk, the peak rate of Po- Schwann cell division reached less than half the peak rate for Po- cells in the sciatic nerve, and cell division fell to a level barely above the control value by postoperative day 4. In the sciatic nerve the number of macrophages, which were identified by monoclonal antibody ED1, rose sharply during the first postoperative day and peaked at day 2. These results provide strong evidence that non-myelin-forming and myelin-forming Schwann cells contribute approximately equally to the initial burst of Schwann cell proliferation seen in the distal stump of the transected rat sciatic nerve. They also indicate that the proliferative response of non-myelin-forming cells is substantially greater in nerves containing many myelinated fibres than in essentially unmyelinated nerves. The timing of macrophage recruitment in the sciatic nerve is consistent with the hypothesis that macrophages are an important source of Schwann cell mitogens during nerve degeneration.