酵母表达鲑鱼降钙素的降血钙活性和药动学研究

Hypocalcemia effect and pharmacokinetic study of recombinant Saccharomyces cerevisiae expressing salmon calcitonin in rats

目的:研究表达鲑鱼降钙素的转基因酵母(yAGA2-r-sCT)的降血钙活性及在大鼠体内的药动学特征。方法:Tsuruo-ka法制备高钙血大鼠模型,观察给药后血浆钙浓度的变化。随机分组单剂量给药试验设计单剂量灌胃yAGA2-r-sCT0.5g.kg-1和肌肉注射密钙息(Miacalcic,Mia)100IU.kg-1进行药物代谢动力学研究,酶联免疫吸附法测定各时间点血药浓度,DAS2.0药动学软件计算出相应的药动学参数,t检验比较2种制剂的药动学参数。结果:灌胃yAGA2-r-sCT0.5及1g.kg-1,静脉注射帕米磷酸二钠(pamidronate,Pam)5mg.kg-1,肌肉注射Mia100IU.kg-1均有明显降低血浆钙浓度的作用,经配对t检验,三者用药后1h的血钙变化率差异无显著性(P>0.05)。四参数回归方程为OD=-7×10-7C3+3×10-4C2+7.3×10-3C-0.0761(r=0.9985),检测范围为5～200μg.L-1,最低检测限为5μg.L-1,日内和日间RSD小于8.6%;单剂量灌胃yAGA2-r-sCT、肌肉注射Mia,Tmax分别为(3.00±0.58)和(1.00±0.29)h,Cmax分别为(106.00±21.17)和(132.00±27.15)μg.L-1,T1/2α分别为(2.29±0.39)和(0.08±0.21)h,T1/2β分别为(3.86±0.67)和(2.49±0.52)h,Ka分别为(0.43±0.22)和(13.99±0.43)h-1,AUC0-t分别为(797.13±134.13)和(598.0±116.33)μg.h.L-1,AUC0-∞分别为(858.56±160.18)和(621.84±125.60)μg.h.L-1,MRT0-t分别为(5.44±1.11)和(4.26±0.70)h,MRT0-∞分别为(6.59±1.17)和(4.89±1.11)h,说明yAGA2-r-sCT与市售Mia在大鼠体内的药动学特征差异具有显著性(P<0.05或0.01)。结论:yA-GA2-r-sCT可显著降低血钙。酶联免疫吸附法测定鲑鱼降钙素含量的方法稳定,结果准确可靠。yAGA2-r-sCT与市售Mia相比,yAGA2-r-sCT显著改善了鲑鱼降钙素的药动学性质,具有缓释和长效的作用。

Objective：To study hypocalcemia effect and pharmacokinetics of recombinant Saccharomyces cerevisiae expressing salmon calcitonin（yAGA2-r-sCT）given orally in Wistar rats.Methods：The plasma calcium concentration of the hypercalcemia rat model induced by Tsuruoka’s process was measured by LX20 Beckman Full Automatic Biochemistry Analyzer.yAGA2-r-sCT as sustained-release salmon calcitonin（sCT）delivery system was orally administrated to rats at a single dosage of 0.5 g·kg-1.Miacalcic（Mia）was intramuscularly administrated to rats at a single dosage of 100 IU·kg-1.The plasma concentration of sCT was measured by ELISA and the pharmacokinetics parameters were calculated and analyzed by DAS 2.0 program.Results：ig yAGA2-r-sCT 0.5,1 g·kg-1,iv pamidronate（Pam）5 mg·kg-1 andim Mia 100 IU·kg-1 reduced concentration of calcium in plasma obviously and there was no difference of mean changes of calcium at the time point of 1 hour among the three kinds of preparations（P0.05）.The four-parameter regression equation was described as following：OD=-7×10-7C3＋3×10-4C2＋7.3×10-3C-0.0761（r=0.9985）.The detectable concentration was ranging from 5 to 200 μg·L-1.Minimum detectable concentration was 5 μg·L-1.The intra-day and inter-day RSDs were less than 8.6%.The major pharmacokinetic parameters of yAGA2-r-sCT and Mia were showen as following：Tmax were（3.00±0.58）and（1.00±0.29）h respectively,Cmax were（106.00±21.17）and（132.00±27.15）μg·L-1 respectively,T1/2α were（2.29±0.39）and（0.08±0.21）h respectively,T1/2β were（3.86±0.67）and（2.49±0.52）h respectively,Ka were（0.43±0.22）and（13.99±0.43）h-1 respectively,AUC0-t were（797.13±134.13）and（598.00±116.33）μg·h·L-1 respectively,AUC0-∞ were（858.56±160.18）and（621.84±125.60）μg·h·L-1,respectively,MRT0-t were（5.44±1.11）and（4.26±0.70）h,respectively,MRT0-∞ were（6.59±1.17）and（4.89±1.11）h,respectively.Conclusion：The results showed that the yAGA2-r-sCT have the best effect on the decreased plasma calcium level and the process of determination with ELISA is stable and reliable results obtained.yAGA2-r-sCT shows characteristic of sustained-release and higher effect compared with Mia.