Multiple sclerosis is a chronic progressive neurological disorder that has few distinctive biomarkers associated with disease progression or response to therapy. This research investigated whether non-invasive imaging correlated with animal behavior and morphological indicators of disease in response to serum levels of [Met⁵]-enkephalin. Using the experimental autoimmune encephalomyelitis (EAE) model, adult female C57BL/6 J mice were randomized to receive daily injections of 0.1 mg/kg naltrexone (NTX) (= low dose naltrexone, LDN), 10 mg/kg Opioid Growth Factor (OGF) (chemically termed [Met⁵]-enkephalin) or saline beginning at the time of disease induction. Daily composite behavior scores were recorded over a 30-day period based on tail tone, gait, righting reflex, and limb strength. Prior to disease onset (day 7), and at peak disease (day 18), mice were imaged and tissues (blood and spinal cord) collected at day 30 for serum analyses of OGF and morphology. Serum OGF levels of EAE mice treated with saline were significantly reduced from baseline and from normal mice. Longitudinal cohort data demonstrated an increase in fractional anisotropy in all cohorts by day 18. There was a significant decrease in radial diffusivity in the saline group seen at day 18 whereas the axial diffusivity was not altered amongst treatment groups. Treatment with OGF or LDN resulted in mean diffusivity rates that were comparable to baseline (normal) levels at days 7 and 18. Luxol fast blue staining of the lumbar spinal cords demonstrated a 16 % reduction in myelin staining in saline treated EAE animals when compared to OGF and LDN treated EAE mice. Immunohistochemistry with Olig2 (pan-oligodendrocyte marker) and myelin basic protein (MBP) revealed that OGF and LDN treatment restored the area (%) of MBP and number of oligodendrocytes to that of normal spinal cord (∼75 %). Saline treated EAE mice had more demyelination and fewer oligodendrocytes than normal mice. Collectively, these data suggest that a panel of biomarkers including imaging, serum biomarker levels, and behavior correlate with progression of disease, and may begin to validate use of specific non-invasive markers for MS.

多发性硬化症是一种慢性进行性神经系统疾病，几乎没有与疾病进展或治疗反应相关的独特生物标志物。这项研究调查了无创成像是否与动物行为和疾病形态学指标相关，以响应 [Met ⁵ ]-脑啡肽的血清水平。使用实验性自身免疫性脑脊髓炎 (EAE) 模型，成年雌性 C57BL/6 J 小鼠随机接受每日注射 0.1 mg/kg 纳曲酮 (NTX)（= 低剂量纳曲酮，LDN）、10 mg/kg 阿片类生长因子 (OGF) )（化学上称为 [Met ⁵]-脑啡肽）或生理盐水在疾病诱导时开始。根据尾音、步态、翻正反射和肢体力量，在 30 天内记录每日综合行为评分。在疾病发作之前（第 7 天）和疾病高峰期（第 18 天），在第 30 天对小鼠进行成像并收集组织（血液和脊髓）用于 OGF 和形态学的血清分析。用生理盐水处理的 EAE 小鼠的血清 OGF 水平与基线和正常小鼠相比显着降低。纵向队列数据表明，到第 18 天所有队列的各向异性分数增加。在第 18 天观察到盐水组的径向扩散率显着降低，而治疗组之间的轴向扩散率没有改变。在第 7 天和第 18 天，用 OGF 或 LDN 处理产生的平均扩散率与基线（正常）水平相当。与相比之下，腰脊髓的 Luxol 快速蓝染色表明，在盐水处理的 EAE 动物中髓鞘染色减少了 16% OGF 和 LDN 处理的 EAE 小鼠。Olig2（泛少突胶质细胞标记物）和髓鞘碱性蛋白（MBP）的免疫组织化学显示，OGF 和 LDN 治疗使 MBP 的面积（％）和少突胶质细胞的数量恢复到正常脊髓的面积（~75％）。与正常小鼠相比，盐水处理的 EAE 小鼠脱髓鞘更多，少突胶质细胞更少。总的来说，这些数据表明，包括成像、血清生物标志物水平和行为在内的一组生物标志物与疾病的进展相关，并且可能会开始验证特定非侵入性标志物对 MS 的使用。