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目的探讨绝经后骨质疏松(PMOP)模型兔骨髓脂肪酸成分变化规律。方法 12只5月龄雌性新西兰大白兔随机分为假手术(SHAM)及去势(OVX)组(n=6/组)。分别在基线及术后3、6个月行磁共振波谱(MRS)及骨密度(BMD)扫描测定骨髓饱和脂质含量(SLC)及不饱和脂质指数(ULI)、BMD。离体L4及左侧股骨生物力学测试。结果 OVX后SLC呈显著性增高而ULI逐渐降低,术后3个月SHAM及OVX组SLC分别为(34.0±5.7)%、(41.7±7.2)%,差异有统计学意义(P<0.05),而组间ULI至术后6个月才有显著性差异。术后3、6个月OVX组SLC较基线分别增高27.1%、63.4%,而ULI较基线分别降低18.2%、32.3%。OVX组BMD呈渐进性降低,至术后6个月组间BMD差异有统计学意义(P<0.05)。OVX组术后6个月L3~L4及股骨近端BMD分别较基线降低21.5%、14.1%,L4最大抗压缩载荷及抗压缩强度较SHAM组分别降低48.9%、49.0%,而股骨最大抗弯曲载荷及弹性模量较SHAM组分别降低16.4%、20.5%(P均<0.05)。L3~L4及股骨BMD与SLC值负相关(r分别为-0.570、-0.672,P均<0.01),而与ULI值存在正相关(r分别为0.506、0.613,P均<0.05)。结论 PMOP骨受损伴随着骨髓饱和脂质增多而不饱和脂质降低,MRS可动态评价骨髓脂质成分。
Objective To investigate the changes of fatty acid composition in bone marrow of postmenopausal osteoporosis (PMOP) model rabbits. Methods Twelve female New Zealand white rabbits aged 5 months were randomly divided into sham operation (SHAM) and ovariectomized (OVX) groups (n = 6 / group). Bone marrow saturated lipid content (SLC), unsaturated fatty index (ULI) and BMD were measured at baseline and at 3 and 6 months after operation by MRS and BMD. Ex vivo L4 and left femur biomechanical testing. Results The SLC in OVX group was significantly higher than that in ULX group (P <0.05), and the ULI decreased gradually. The SLC in SHAM group and OVX group at 3 months after operation were 34.0 ± 5.7% and 41.7 ± 7.2%, respectively, with statistical significance (P <0.05) Between the group ULI to 6 months after the significant difference. At 3 and 6 months after operation, the SLC in OVX group increased by 27.1% and 63.4% respectively compared with baseline, while the ULI decreased by 18.2% and 32.3% respectively compared with baseline. BMD in OVX group decreased gradually, and there was significant difference in BMD between 6 months after operation (P <0.05). The L3 ~ L4 and proximal femur BMD of OVX group decreased by 21.5% and 14.1% respectively compared with baseline at 6 months after operation, and the maximum compressive load and compressive strength of L4 decreased by 48.9% and 49.0% respectively compared with SHAM group, while the maximum flexion resistance The load and elastic modulus decreased by 16.4% and 20.5% respectively compared with SHAM group (all P <0.05). L3 ~ L4 and femur BMD were negatively correlated with SLC (r = -0.570, -0.672, P <0.01, respectively), but positively correlated with ULI (r = 0.506,0.613, P <0.05). CONCLUSIONS: PMOP is impaired with the increase of saturated lipids in bone marrow and the decrease of unsaturated lipids. MRS can evaluate bone marrow lipid components dynamically.