目的 研究维生素D缺乏和过剩对大鼠脑内P-糖蛋白（P-gp）和乳腺癌耐药蛋白（BCRP）功能和表达的影响。方法 18只雄性SD大鼠随机分为对照组、去维生素D（NVD）组和高维生素D（HVD）组，分别使用标准饲料（1 000 IU/kg维生素D）、去维生素D（0 IU/kg维生素D）饲料和高维生素D（20 000 IU/kg维生素D）饲料饲养12周，诱导维生素D缺乏和过剩模型，测定大鼠血清中25-羟基维生素D₃[25（OH） D₃]、1α，25二羟基维生素D₃[1α，25（OH）₂D₃]水平以确证模型。造模成功后，尾iv含罗丹明123（0.2 mg/kg）、哌唑嗪（1 mg/kg）和荧光素钠（2 mg/kg）的混合探针，采用LC-FLU或LC-MS法分别测定大鼠脑皮层、海马和血浆中罗丹明123、哌唑嗪和荧光素钠的浓度，计算脑血比，评价P-gp、BCRP功能和血脑屏障完整性；采用Western blotting法测定大鼠脑皮层和海马P-gp和BCRP的相对表达量。用25（OH） D₃、1α，25（OH）₂D₃分别温孵人微血管内皮细胞（hCMEC/D3），以罗丹明123、哌唑嗪为探针评价细胞中P-gp和BCRP的功能。结果 维生素D缺乏大鼠脑内P-gp功能和表达下调，而维生素D过剩大鼠脑内P-gp功能和表达上调，维生素D缺乏和过剩均不影响大鼠脑内BCRP的功能和表达。25（OH） D₃不影响hCMEC/D3细胞P-gp和BCRP的功能，而1α，25（OH）₂D₃上调hCMEC/D3细胞中P-gp的功能。结论 维生素D缺乏导致的体内1α，25（OH）₂D₃水平降低可能是下调大鼠脑内P-gp的功能和表达的原因之一，而维生素D过剩导致的体内1α，25（OH）₂D₃水平升高可能是上调大鼠脑内P-gp的功能和表达的原因之一。

Objective To study the effect of vitamin D deficiency and excess on the function and expression of brain P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) in rats. Methods Eighteen male SD rats were randomly divided into control group, no vitamin D (NVD) group, and high vitamin D group (HVD). The rats were fed with standard diet (1 000 IU/kg vitamin D), no vitamin D diet (0 IU/kg vitamin D), and high vitamin D diet (20 000 IU/kg vitamin D) for 12 weeks, respectively. The serum concentrations of 25(OH)D₃ and 1α,25(OH)₂D₃ were determined to confirm the successful establishment of the rat model of vitamin D deficiency and vitamin D excess. A mixed probe containing rhodamine 123 (0.2 mg/kg), prazosin (1 mg/kg), and fluorescein sodium (2 mg/kg) was injected into the tail vein of the rats. The concentrations of rhodamine 123, prazosin, and fluorescein sodium in rat cerebral cortex, hippocampus, and plasma were measured. The ratios of brain probe concentration to plasma probe concentration were calculated to evaluate the function of P-gp, BCRP, and the integrity of blood brain barrier. The relative protein expression of P-gp and BCRP in cortex and hippocampus was also measured by Western blotting. hCMEC/D3 cells were used to document the effects of 25(OH)D₃ and 1α,25(OH)₂D₃ on the function on of P-gp and BCRP. Results Function and expression of P-gp in the brain of vitamin D deficient rats were down-regulated, while the function and expression of P-gp in the brain of vitamin D excess rats were up-regulated. Vitamin D deficiency and excess did not affect the function and expression of BCRP in the brain of rats. 25(OH)D₃ did not affect the function of P-gp and BCRP in hCMEC/D3 cells, while 1α,25(OH)₂D₃ up-regulated the function of P-gp in hCMEC/D3 cells.Conclusion The decreased levels of 1α,25(OH)₂D₃ caused by vitamin D deficiency may be one of the reasons for down-regulating the function and expression of brain P-gp in rats, while the increased levels of 1α,25(OH)₂D₃ caused by vitamin D excess may be one of the reasons for up-regulating the function and expression of brain P-gp in rats.

R965

江苏省自然科学基金面上项目（BK20161368）