Akhter M P, Cullen D M, Recker R R
Osteoporosis Research Center, Creighton University, Omaha, NE 68131, USA.
J Clin Densitom. 2002 Summer;5(2):207-16. doi: 10.1385/jcd:5:2:207.
This study presents inbred-strain-related differences in tibial bone adaptation response to low-force loading in four-point bending and sham (pad pressure) arrangements in mice. Our previous work in mice has shown that at relatively high but equal bending forces (9 N or a bending moment of 16.88 N-mm), C57BL/6J mice respond with significantly greater bone formation than C3H/HeJ mice. Because of high tibial strains, the majority of the bone response in our previous study was woven bone. In this, study, we reduced the loading forces to 5 N or a bending moment of 9.38 N-mm (to decrease the woven-bone formation response) and investigated inbred-strain-related bone adaptation differences resulting from bending and sham loading (reported here for the first time in C57BL/6J) in these mice. Twenty-four female mice within each inbred mouse strain (C3H/HeJ [C3H] and C57BL/6J [B6]) were randomly divided into the two loading groups (12 per group sham and bending, total of 48 mice). All of the external loading was done for 36 cycles at 2 Hz, 3 d/wk for 3 wk. The bone adaptation response at lower forces exhibited a pattern similar to that seen for the higher forces in the previous study, suggesting that the patterns of bone adaptation were inbred strain related and independent of bending force magnitude. The bending-related periosteal mineral apposition surface (pMS) and mineral apposition rate (MAR) were respectively 40% and 45% greater in B6 than in C3H. The cortical bone adaptation response to bending was greater when compared to sham or pad pressure for each inbred strain of mice, suggesting that the majority of the bone adaptation response was the result of bending stimulus and not local pressure from pad contact. In addition, regardless of loading arrangement (sham or bending), the bone adaptation response in C57BL/6J mice was greater than C3H/HeJ.
本研究呈现了在小鼠四点弯曲和假手术（垫压力）装置中，近交系相关的胫骨骨对低力负荷适应反应的差异。我们之前在小鼠身上的研究表明，在相对较高但相等的弯曲力（9 N或弯曲力矩16.88 N-mm）下，C57BL/6J小鼠的骨形成反应明显大于C3H/HeJ小鼠。由于胫骨应变较高，我们之前研究中的大部分骨反应是编织骨。在本研究中，我们将负荷力降低至5 N或弯曲力矩9.38 N-mm（以减少编织骨形成反应），并研究了这些小鼠中弯曲和假手术负荷导致的近交系相关骨适应差异（本文首次在C57BL/6J中报道）。每个近交小鼠品系（C3H/HeJ [C3H]和C57BL/6J [B6]）中的24只雌性小鼠被随机分为两个负荷组（每组12只，假手术组和弯曲组，共48只小鼠）。所有外部负荷均在2 Hz下进行36个周期，每周3天，共3周。较低力下的骨适应反应呈现出与之前研究中较高力下相似的模式，表明骨适应模式与近交系有关，且与弯曲力大小无关。B6小鼠中与弯曲相关的骨膜矿物质沉积表面（pMS）和矿物质沉积率（MAR）分别比C3H小鼠高40%和45%。对于每个近交系小鼠，与假手术或垫压力相比，皮质骨对弯曲的适应反应更大，这表明大部分骨适应反应是弯曲刺激的结果，而不是垫接触产生的局部压力。此外，无论负荷方式（假手术或弯曲）如何，C57BL/6J小鼠的骨适应反应都大于C3H/HeJ小鼠。
