5-氨基乙酰丙酸介导继发性甲状旁腺功能亢进症大鼠甲状旁腺荧光特性的研究

Fluorescence characteristics in parathyroid glands by 5-aminolevulinic acid in secondary hyperparathyroidism rats

目的研究5-氨基乙酰丙酸(5-aminolevulinic acid,5-ALA)定位继发性甲状旁腺功能亢进症(secondaryhyperparathyroidism,SHPT)大鼠甲状旁腺组织方法的可行性,并观察其代谢产物原卟啉Ⅸ(protoporphyrinⅨ,PpⅨ)在甲状旁腺组织积聚的动态变化。方法 16只6～8周龄健康雌性SD大鼠,体质量180～200 g,分为手术组(5/6肾切除+高磷饲养,n=12)和假手术组(正常磷饲养,n=4),28 d后,2组大鼠腹腔注射500 mg/kg 5-ALA,405 nm蓝光探测2组大鼠颈部甲状腺区域,应用微型光纤光谱仪检测甲状腺、甲状旁腺组织内PpⅨ在不同时间的荧光强度、波长,并取其行组织学检查。结果在注射5-ALA后,2组大鼠甲状旁腺组织均可用肉眼观察,大部分位于甲状腺外侧。手术组在0.5～4 h均可见甲状旁腺组织显红色荧光,假手术组在1～3 h均可见红色荧光,其中2组荧光强度在2 h达到高峰,手术组峰值显著高于假手术组(P<0.05)。在注入5-ALA后2 h,手术组和假手术组内甲状旁腺组织荧光强度均高于甲状腺组织10倍。组织学检查确认红色荧光组织均为增生的甲状旁腺细胞。结论 5-ALA介导SHPT甲状旁腺组织的高荧光强度的特点为术中辨别增生与正常的甲状旁腺组织提供了重要的依据。

Objective To investigate the feasibility of the application of 5-aminolevulinic acid （5-ALA）-induced fluorescence for the detection of parathyroid glands in secondary hyperparathyroidism rats and to observe the dynamic changes of the accumulation of endogenous synthesized protoporphyrin Ⅸ （PpⅨ） after administration of 5-ALA. Methods Twelve female Sprague-Dawley rats, weighing 180-200 g, were divided into 2 groups： an operation group （5/6 nephrectomy plus high phosphorus food） and a sham operation group （normal phosphorus food）. After 28 d, the two groups of rats were photosensitized by intraperitoneal injection of ALA solution. After surgical exposure of thyroid gland and parathyroid gland, the operative sites were observed under blue light （405nm） using a miniature fiber optic spectrometer to assess the fluorescence intensity of thyroid and parathyroid tissues. Histological examination of the fluorescent tissues was performed. Results After intraperitoneal injection of 5-ALA, parathyroid gland fluorescence was observed in two groups of rats. The red fluorescence of parathyroid glands was located on the posterolateral thyroid glands and could be seen by naked eyes. The red fluorescence of the parathyroid glands could be seen from 0.5 h to 4 h in the operation group and from 1 h to 3 h in the sham operation group. The peak intensity at 2 h in the operation group was significantly higher than that in the sham operation group （P〈0.05）, and the fluorescence intensity was 10 times higher in the parathyroid glands than in the thyroid gland in both of the two groups. The histology of the fluorescent tissues confirmed the tissue with red fluorescence was the proliferated parathyroid gland under a light microscope. Conclusion 5-ALA-induced high intensity fluorescence suggests an important support to identify the hyperplastic parathyroid glands rather than normal glands and improve the success of parathyroidectomy. It has potential clinical value in treatment of parathyroid diseases.