中文摘要：

目的考察烟酰胺对压力诱发的兔腰椎间盘退变的保护作用。方法取24只日本大白兔随机分入1-6组,采用可控轴向压力致兔腰椎间盘退变模型,以98 N压力诱发椎间盘退变,并按分组要求灌胃给予烟酰胺：第1组2只,安装加压装置不予加压或给药;第2组2只,给予50 mg/（kg.d）烟酰胺灌胃1周;第3组5只,以98 N压力加压1周;第4组5只,以98 N压力加压1周,去除压力自行恢复1周;第5组5只,加压1周,去除压力后给予50 mg/（kg.d）烟酰胺灌胃1周;第6组5只,加压1周,去除压力后恢复1周,自加压开始时持续给予50 mg/（kg.d）烟酰胺灌胃2周。Thompson分级法及腰椎间盘磁共振成像（MRI）评价退变程度;苏木精-伊红染色、Ⅱ型胶原免疫组化染色及藏红O-快绿染色观察其组织学改变;P16INK4A免疫组化染色检测细胞增殖和衰老状态的变化。结果①第2组椎间盘未见明显退变;第3组5只动物Thompson分级均为Ⅱ级,第4组4只为Ⅱ级,1只为Ⅲ级,第5组2只为Ⅰ级,3只为Ⅱ级,第6组3只为Ⅰ级,2只为Ⅱ级。MRI也显示,服用烟酰胺的动物椎间盘退变程度有所减轻。②Ⅱ型胶原免疫组化染色显示,第6组纤维环Ⅱ型胶原含量较第4组高约53.2%（P〈0.01）。③第2组藏红O染色强度较第1组有所上升;第5、6组髓核和纤维环染色强度均高于第4组的相对应部位,其中以第6组髓核染色强度上升最为明显（均P〈0.01）。④P16INK4A免疫组化显示,P16INK4A阳性率随烟酰胺给药时间延长而降低。结论烟酰胺有助于减轻压力对椎间盘的损伤,能够促进压力损伤后的椎间盘恢复。

英文摘要：

Objective To investigate the protective effects of nicotinamide against axial loading-induced rabbit intervertebral disc（IVD） degeneration.Methods Twenty-four Japanese white rabbits were randomly divided into 6 groups.Rabbit lumbar disc degeneration model was established by the controllable axial pressure of 98 N.The rabbits were given nicotinamide orally following the grouping.In group 1,two rabbits were equipped with the controllable axial pressure device but not subjected to pressure or nicotinamide;In group 2,two rabbits were administered nicotinamide of 50 mg/（kg·d） for one week by gastric gavage;In group 3,five rabbits were loaded with controllable axial pressure of 98 N for one week;In group 4,five rabbits were loaded with controllable axial pressure of 98 N for one week,then restored one week by the removal of the pressure;In group 5,five rabbits were loaded with controllable axial pressure of 98 N for one week,and given nicotinamide of 50 mg/（kg·d） for one week prior to the removal of the pressure;In group 6,five rabbits were loaded with controllable axial pressure of 98 N for one week and restored one week,and simultaneously given nicotinamide of 50 mg/（kg·d） for two weeks via gastric gavage.The rabbit lumbar MRI and Thompson grades were used to score IVD degeneration;HE staining,type Ⅱ collagen immunohistochemistry staining and Safranin O-Fast Green staining were done to assess the histological changes in the IVD matrix;P16INK4A immunohistochemistry staining was used to detect the state of cell senescence.Results ① Immunohistochemistry staining of type Ⅱ collagen demonstrated that the pathological changes of IVDs were alleviated,and contents of collagen were increased by 53.2% in the nicotinamide-treated groups as compared with group 4（P〈0.01）;②Safranin O-Fast Green staining intensity of both nucleus pulposus（NP） and annular fibrosus in group 2 was increased as compared with group 1.The staining intensity in NP of groups 5 and 6 were increased as compared with group