经玻璃紫外线照射对大鼠25-羟维生素D水平及骨代谢的影响

Effect of ultraviolet irradiation through glass on the level of 25-hydroxy vitamin D and bone metabolism in rats

摘要:

目的：目前研究发现B型紫外线照射与血清25-羟维生素D［25-hydroxy vitamin D, 25-（OH）D］水平有剂量-效应关系，并且维生素D与骨代谢相关。该研究探讨经玻璃紫外线照射对大鼠25-（OH）D及骨代谢的影响。方法：选用30只Wistar大鼠建立不同紫外线暴露方式的动物模型，饲以缺乏维生素D饮料，随机分为避光组，紫外线直接照射160 min组，简称直射组，紫外线经单层玻璃照射160 min组，简称经玻组。每组各10例。21 d实验结束时，测定各组大鼠血清25-(OH) D、甲状旁腺激素(parathyroid hormone, PTH)、骨碱性磷酸酶(bone alkaline phosphatase, BALP)、骨钙素(osteocalcin, OC)和骨Ⅰ型胶原羧基末端肽(carboxyterminal cross-linked telopeptide of type I collagen, ICTP)的浓度及骨密度(bone mieral density, BMD)。结果：经玻组骨密度（BMD）为0.036±0.002 g/cm2，显著高于避光组(P<0.01)； ICTP浓度0.181±0.067 μg/L,显著低于避光组(P<0.01)；PTH、25-（OH）D、BALP及OC浓度分别为3.72±0.38 pg/mL、28.67±1.35 nmol/L、25.03±4.65 μg/mL和0.559±0.067 ng/mL，与避光组差异无显著性（P>0.05）。 经玻组BALP和ICTP水平及BMD与直射组差异无显著性(P>0.05)；OC和PTH浓度显著高于直射组(P<0.05)；25-（OH）D水平显著低于直射组（P<0.01）。结论：经单层玻璃的紫外线照射不能显著提高血浆25-（OH）D水平，但可降低维生素D缺乏造成的骨转化率升高并提高骨密度，与直接紫外线照射达到相似效果。［中国当代儿科杂志，2009，11（2）：138-141］

Abstract:

OBJECTIVE: Some research has shown that there is a dose-dependent relationship between ultraviolet B (UVB) and serum levels of 25-hydroxy vitamin D［25-(OH)D］\. Vitamin D is correlated with bone metabolism. This study aimed to explore the effect of UVB irradiation through glass on serum levels of 25-(OH)D and bone metabolism in rats. METHODS: Wistar rats were fed with vitamin D deficient diet and randomly divided into three groups: no UVB exposure, direct UVB exposure (160 min/d) and indirect UVB exposure (through glass) (160 min/d). By 21 days after exposure, bone mineral density (BMD) and serum levels of 25-(OH)D, parathyroid hormone (PTH), osteocalcin (OC), bone alkaline phosphatase (BALP) and carboxyterminal cross-linked telopeptide of type I collagen (ICTP) were measured. RESULTS: BMD (0.036±0.002 g/cm2) in the indirect UVB exposure group was significantly higher than that in the no UVB exposure group (0.029±0.002 g/cm2) (P<0.01). Serum ICTP level in the indirect UVB exposure group was significantly lower than that in the no UVB exposure group (0.181±0.067 μg/L vs 0.194±0.066 μg/L; P<0.01). Serum levels of PTH, 25-(OH)D, BALP and OC in the indirect UVB exposure group were not significantly different from those in the no UVB exposure group. Compared with the direct UVB exposure group, serum levels of OC (0.559±0.067 ng/mL vs 0.278±0.067 ng/mL; P<0.05) and PTH (0.181±0.067 μg/L vs 0.109±0.067 μg/L; P<0.05) in the indirect UVB exposure group significantly increased, while serum levels of 25-(OH)D significantly decreased (28.67±1.35 nmol/L vs 34.69±4.30 nmol/L; P<0.01). There were no significant differences in BMD and serum levels of BALP and ICTP between the indirect UVB exposure and the direct UVB exposure groups. CONCLUSIONS: UVB irradiation through glass cannot elevate serum levels of 25-(OH)D, but can decrease bone turnover rate and increase BMD. The effect of UVB irradiation through glass on bone metabolism is similar to that of direct UVB irradiation.［Chin J Contemp Pediatr, 2009, 11 (2):138-141］