Research Unit of Experimental Neurotraumatology, Department of Neurosurgery, Medical University Graz, Auenbruggerplatz 2.2, 8036 Graz, Austria.
Department of Neurology, Medical University Graz, Auenbruggerplatz 22, 8036 Graz, Austria.
Exp Neurol. 2017 Aug;294:32-44. doi: 10.1016/j.expneurol.2017.04.014. Epub 2017 Apr 27.
Cortical demyelination is a common finding in patients with chronic multiple sclerosis (MS) and contributes to disease progression and overall disability. The exact pathomechanism that leads to cortical lesions is not clear. Research is limited by the fact that standard animal models of multiple sclerosis do not commonly affect the cortex, or if they do in some variants, the cortical demyelination is rather sparse and already remyelinated within a few days. In an attempt to overcome these limitations we implanted a tissue-compatible catheter into the cortex of Dark Agouti rats. After 14days the rats were immunized with 5μg myelin oligodendrocyte glycoprotein (MOG) in incomplete Freund's Adjuvant, which did not cause any clinical signs but animals developed a stable anti-MOG antibody titer. Then the animals received an injection of proinflammatory cytokines through the catheter. This led to a demyelination of cortical and subcortical areas starting from day 1 in a cone-like pattern spreading from the catheter area towards the subarachnoid space. On day 3 cortical demyelination already expanded to the contralateral hemisphere and reached its peak between days 9-15 after cytokine injection with a widespread demyelination of cortical and subcortical areas of both hemispheres. Clinically the animals showed only discrete signs of fatigue and recovered completely after day 15. Even on day 30 we still were able to detect demyelination in subpial and intracortical areas along with areas of partial and complete remyelination. Loss of cortical myelin was accompanied with marked microglia activation. A second injection of cytokines through the catheter on day 30 led to a second demyelination phase with the same symptoms, but again no detectable motor dysfunction. Suffering of the animals appeared minor compared to standard Experimental Autoimmune Encephalomyelitis and therefore, even long-term observation and repeated demyelination phases seem ethically acceptable.
皮质脱髓鞘是慢性多发性硬化症（MS）患者的常见表现，并导致疾病进展和整体残疾。导致皮质病变的确切病理机制尚不清楚。研究受到限制，因为多发性硬化症的标准动物模型通常不会影响皮质，如果在某些变体中影响，皮质脱髓鞘也相当稀疏，并且在几天内就已经再髓鞘化。为了克服这些限制，我们将组织相容性导管植入暗褐家鼠的皮质中。 14 天后，用 5μg 髓鞘少突胶质细胞糖蛋白（MOG）在不完全弗氏佐剂中免疫大鼠，这不会引起任何临床症状，但动物产生了稳定的抗 MOG 抗体滴度。然后，通过导管向动物注射促炎细胞因子。这导致从第 1 天开始，以从导管区域向蛛网膜下腔呈锥形扩散的方式，皮质和皮质下区域出现脱髓鞘。第 3 天，皮质脱髓鞘已经扩展到对侧半球，在细胞因子注射后第 9-15 天达到高峰，两侧半球的皮质和皮质下区域广泛脱髓鞘。临床上，动物仅表现出轻微的疲劳迹象，并在第 15 天后完全恢复。即使在第 30 天，我们仍然能够检测到沿软脑膜和皮质内区域以及部分和完全再髓鞘化区域的脱髓鞘。皮质髓鞘丢失伴有明显的小胶质细胞激活。第 30 天通过导管再次注射细胞因子会导致出现具有相同症状的第二次脱髓鞘阶段，但仍未检测到运动功能障碍。与标准实验性自身免疫性脑脊髓炎相比，动物的痛苦似乎较小，因此，即使是长期观察和重复脱髓鞘阶段似乎在伦理上也是可以接受的。
