日光暴露方式及维生素D摄入与大鼠肾脏维生素D受体表达及骨矿化改变

Effect of different methods of sunlight exposure and vitamin D supplement on vitamin D receptor expression and bone mineral addition rate in rats

目的探讨不同日光暴露方式的紫外线强度变化以及添加维生素D对大鼠骨代谢的影响。方法选用21d断乳Wistar大鼠72只,随机分为直接日光暴露、正常饲料组(直晒+D组),直接日光暴露、缺乏维生素D饲料组(直晒缺D组),双层玻璃遮挡下日光暴露、正常饲料组(隔晒+D组),双层玻璃遮挡下日光暴露、缺乏维生素D饲料组(隔晒缺D组),避光正常饲料组(避光+D组)及避光缺乏维生素D饲料组(避光缺D组)。实验期60d。ZQJ-254型紫外线测定仪检测B波紫外线强度。实验结束后检测大鼠肾脏维生素D受体(vitamin D receptor,VDR)表达情况及胫骨骨小梁矿化沉积率(mineral addition rate,MAR)的差异。结果①室外紫外线强度为0.0429w/m2,双层玻璃遮挡后紫外线强度为0.0064w/m2,紫外线强度衰减了85.1%。②直晒缺D组的肾脏VDR表达(0.56±0.14)与隔晒缺D组(0.56±0.08)比较差异无统计学意义,P=0.89;避光+D组(0.46±0.07)与避光缺D组(0.47±0.08)比较差异无统计学意义,P=0.828。③骨矿化沉积率直晒缺D组[(0.91±0.23)μm/d]与隔晒缺D组[(0.72±0.18)μm/d]比较差异无统计学意义,P=0.091;避光+D组[(0.71±0.19)μm/d]与避光缺D组[(0.64±0.21)μm/d]比较差异无统计学意义,P=0.563;直晒+D组[(1.24±0.26)μm/d]与直晒缺D组[(0.91±0.23)μm/d]比较差异有明显统计学意义,P=0.004;直晒+D组/避光+D组,P<0.001。结论日光暴露是大鼠骨矿化的主要影响因素;虽然双层玻璃遮挡后的紫外线强度削减了85.1%,但在暴露时间足够长的情况下,隔着玻璃进行日光浴可以使大鼠肾脏VDR的表达接近直接日光暴露组;添加维生素D可增强日光暴露对骨矿化的作用。

Objective To study the influence of ultraviolet intensity from different sun exposure and vitamin D supplement on vitamin D receptor （VDR） expression and bone mineral addition rate （MAR） in rats. Methods Seventytwo 21-day-old male Wistar rats were divided into six groups randomly, direct sunlight exposure＋VitD, direct sunlight exposure-VitD, indoors sunlight exposure＋VitD, indoors sunlight exposure-VitD, and without sunlight exposure＋VitD, without sunlight exposure-VitD. UVB was measured by ZQJ-254 ultraviolet rays detector. VDR mRNA expression in kidney and bone MAR were measured after 60 days. Results The mean intensity of outdoor UVB was 0.042 9 w/m^2. After passing through double-ply glass, about 85.1% UVB intensity was lost and the indoor UVB was only 0.006 4 w/m^2. Without vitamin D supplement, the VDR expression between direct sunlight exposure group （0.56 ± 0.14） and indoor sunlight exposure group （0.56± 0.08） was not significantly different, P = 0.910. Without sunlight exposure, the VDR expression between vitamin D supplement group （0.46 ± 0.07） and non-vitamin D supplement group （0.47 ± 0.08） was not significantly different, P = 0.828. Without vitamin D supplement, the mean MAR between direct sunlight exposure group （0.91± 0.23 μm/d） and indoor sunlight exposure group （0.72 ＋ 0.18 μm/d） was not significantly different, P = 0.091. Without sunlight exposure, the meanMAR between vitamin D supplement group （0.71 ±0.19 μm/d） and non-vitamin D supplement group （0.64 ±0.21μm/d） was not significantly different, P =oup （1.24 ± 0.26 μm/d） and direct sunlight exposure-VitD group （0.91 ± 0.23 μm/d） was significantly different, P =0.004. Conclusions Sunlight exposure is one of the main interference factors in VDR mRNA expression and MAR in rats. Although 85.1% UVB in sunlight is lost after passing thrgugh double-ply glass, the indoor sunlight exposure almost has the same effect on VDR mRNA expression and MAR as direct sunlight exposure after the long time exposure in rats. Vitamin D plays a role of cooperator with sunlight exposure in MAR.