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A mechanism for the increased activity of α-amylase in serum upon radiation exposure

辐射暴露后血清中α-淀粉酶活性增加的机制

基本信息

批准号：
16591242
负责人：
AKASHI Makoto
金额：
$ 1.98万
依托单位：
NATIONAL INSTITUTE OF RADIOLOGICAL SCIENCES
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16591242/
关键词：
irradiaton amylase salivary gland tight junction

项目摘要

α-amylase (EC.3.2.1.1) catalyzes the specific cleavage of α-1.4 glucan bonds in polysaccharides such as starch. α-amylase is produced by the pancreas (P-amylase) and the salivary glands (S-amylase). Stresses including radiation and major surgery are known to increase the levels of α-amylase in serum. Moreover, increased levels of α-amylase were observed in workers who were exposed to high-dose radiation in the Tokai-mura criticality accident, and they developed a painful bilateral swelling of the parotid glands. However, the mechanism is not fully understood. In this study, we examined mechanisms for the increased level and activity of α-amylase in blood by radiation exposure. Irradiation with doses of 3.5 to 14 Gy increased α-amylase activity in C3H/He mouse plasma in dose-dependent manner. A maximal level of α-amylase was observed at 12 h after irradiation (about 3-fold), and after that, level of α-amylase was decreased to about 2-fold at 24 h compared with that of control mouse plas … More ma. Non-denatured polyacrylamide gel fractionation of the plasma followed by starch-iodine staining showed that S-amylase was dominant in the increased activity by irradiation and P-amylase was not affected. On the other hand, irradiation inhibited increase in the flow rate of saliva induced by pilocarpine and decreased the α-amylase activity in saliva. Furthermore ligation of parotid-duct resulted in the increased α-amylase activity to about 3-fold in blood. We tested whether irradiation increases the production of α-amylase in a human salivary gland cell line HSY by western blot analysis and RT-PCR. When the HSY cells cultured on Matrigel, these cells differentiated into more mature cells ; they formed acinar structure. Irradiation failed to increase the activity or the mRNA level of α-amylase in these HSY cells. We prepared acinar cells from the parotid glands of mice and cultured them in vitro. Irradiation decreased the α-amylase activity in these primarily cultured cells and increased the activity in the culture supernatants. Irradiation did not affect apoptosis. Microscope images of cells stained with anti-amylase antibody showed that irradiation decreased the fluorescence intensities. Furthermore, horseradish peroxidase (HRP) was administered retrogradely as a tracer via a main excretory duct of parotid gland in a rat. The tracer was present in cells from an irradiated rat but not in a control rat. When HRP was injected intravenously, the tight junction prevented the passage of tracer from acinar lumina and intracellular canaliculi into the intercellular space in a control rat. However, the tracer was detected in an irradiated rat. Our results suggest that irradiation may cause increased levels of α-amylase in blood by not altering its production but affecting barrier function of tight junction ; amylase is released into blood vessels through distracted barrier by irradiation. Less

α-淀粉酶（EC. 3.2.1.1）催化多糖如淀粉中α-1.4葡聚糖键的特异性裂解。α-淀粉酶由胰腺（P-淀粉酶）和唾液腺（S-淀粉酶）产生。已知包括放射和大手术在内的应激会增加血清中α-淀粉酶的水平。此外，在东海村临界事故中暴露于高剂量辐射的工人中观察到α-淀粉酶水平升高，他们的腮腺出现疼痛的双侧肿胀。然而，该机制尚未完全理解。在这项研究中，我们研究了辐射暴露导致血液中α-淀粉酶水平和活性升高的机制。3.5 ~ 14戈伊剂量的γ射线照射使C_3 H/He小鼠血浆α-淀粉酶活性呈剂量依赖性增高。α-淀粉酶在照射后12 h达高峰，约为对照组的3倍，照射后24 h下降至对照组的2倍 ...更多信息 MA.非变性聚丙烯酰胺凝胶电泳分离的血浆，然后由淀粉-碘染色表明，S-淀粉酶是占主导地位的活性增加的辐射和P-淀粉酶不受影响。另一方面，照射可抑制毛果芸香碱引起的唾液流速增加，降低唾液中α-淀粉酶活性。结扎腮腺导管可使血液中α-淀粉酶活性增加约3倍。我们用Western印迹分析和RT-PCR检测了照射是否增加人涎腺细胞系HSY中α-淀粉酶的产生。当HSY细胞在Matrigel上培养时，这些细胞分化为更成熟的细胞，它们形成腺泡结构。照射不能提高HSY细胞α-淀粉酶的活性和mRNA水平。我们从小鼠腮腺中制备腺泡细胞并进行体外培养。辐射使原代培养细胞的α-淀粉酶活性降低，培养上清的α-淀粉酶活性升高。辐射不影响细胞凋亡。用抗淀粉酶抗体染色的细胞的显微镜图像显示照射降低荧光强度。此外，辣根过氧化物酶（HRP）作为示踪剂通过腮腺的主要排泄管逆行注射在大鼠。示踪剂存在于受辐射大鼠的细胞中，但不存在于对照大鼠中。当HRP静脉注射时，紧密连接阻止示踪剂从腺泡腔和细胞内小管进入对照大鼠的细胞间隙。然而，示踪剂被检测到辐射大鼠。我们的研究结果表明，辐射可能会导致血液中的α-淀粉酶水平增加，而不是改变其生产，但影响紧密连接的屏障功能;淀粉酶通过辐射分散屏障释放到血管中。少