骨关节炎动物模型的生化及磁共振成像研究

目的动态观察豚鼠关节软骨降解的生化及形态学改变，探讨骨关节炎早期病变机制：研究磁共振成像（MRI）检测早期软骨退变的可能性及其表现。方法选用Harfley雌性豚鼠30只，分为出生后1、3、6个月龄，每组各10只。观察豚鼠膝关节软骨降解情况，测定其血清蛋白多糖和雌二醇水平，取胫骨平台软骨测定羟脯氨酸、糖醛酸含量及含水率。取关节软骨组织作蛋白多糖含量测定和组织病理学检查，同时行双侧膝关节矢状面T1WI、PDW和T2WI成像检查。结果3个月组关节软骨即有降解。豚鼠的雌二醇水平和软骨含水率随年龄的增长而升高，而血清蛋白多糖和软骨糖醛酸含量随年龄的增长而下降，各组间差异有统计学意义（P〈0．05）。软骨羟脯氨酸含量各时间段差异无统计学意义，3个月组关节软骨明显变薄，磁共振（MR）信号强度明显降低。6个月组更加明显，与出生后1个月相比，两者差异均有统计学意义（P〈0．05），关节软骨明湿变薄，MR信号强度明显降低；与对照1个月组比较，两者差异均有统计学意义（P〈0．05）。结论原发性骨关节炎血清及软骨生化指标随年龄增高改变明显。雌激素代谢盯能与原发性骨关节炎的发病机制有关。关节软骨的MR信号强度与蛋白多糖含量具有相关性．蛋白多糖的降解在MRI上表现为软骨厚度的变薄和MRI信号强度的降低。这表明通过MRI检查，有可能发现早期的软骨退变。

Biochemical and magnetic resonance imaging features of cartilage in primary osteoarthritis

Objective To investigate the morphological and biochemical changes of primary knee joint osteoarthritis of guinea pigs and study its initial pathogenesis. To study the appearance of magnetic resonance imaging (MRI) in early stages of cartilage degeneration and to evaluate its values. Methods Thirty female Hartley guinea pigs were divided into postnatal 1, 3 and 6 months groups with 10 animals in each group. The degeneration of knee joint cartilage was observed. The proteoglycan (PG) and estradiol (ET) in serum were measured and the concentration of hydroxyproline (HOP), uronic acid (UA) and water ratio (WR) in articular cartilage were determined. Guinea pigs were scanned with magnetic resonance imaging ,using a 1.5T ASC-NT Gyroscan unit (Philips) magnet with 16 cm coil. Gradient echo sequences and spin echo sequences were performed in the sagittal planes at postnatal 1, 3, 6 months. Then signal intensity and thickness of cartilage were measured. The proteoglycan level was measured biochemically and histochemically. Results Degeneration of knee joint cartilage was seen in guinea pigs of 3 months old. The level of serum ET and cartilage WR were increased with age, while the value of serum PG and cartilage UA were decreased with age. The cartilage thickness and signal intensity were decreased significantly in treated knees compared with postnatal 1 month knees (P<0.05). These changes on magenetic resonance (MR) images were consistent with the change of proteoglycan concentration measured by biochemical analysis and histochemical staining of cartilage. Conclusion Biochemical features of primary osteoarthritis in serum and cartilage change significantly with age. Estradiol metabolism may attribute to the pathogenesis of primary osteoarthritis. It is possible for MRI to detect the early stage cartilage degeneration.