2005 Fiscal Year Final Research Report Summary
A mechanism for the increased activity of α-amylase in serum upon radiation exposure
| Project/Area Number |
16591242
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Radiation science
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| Research Institution | NATIONAL INSTITUTE OF RADIOLOGICAL SCIENCES |
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Principal Investigator |
AKASHI Makoto National Institute of Radiological Sciences, The Department of Radiation Emergency Medicine, Director, 被ばく医療部, 部長 (10222514)
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| Co-Investigator(Kenkyū-buntansha) |
HACHIYA Misao National Institute of Radiological Sciences, The Department of Radiation Emergency Medicine, Senior Researcher, 被ばく医療部, 主任研究員 (00198756)
PARK Sang-hee National Institute of Radiological Sciences, The Department of Radiation Emergency Medicine, Researcher, 被ばく医療部, 研究員 (40392237)
TAKAI Daisaku National Institute of Radiological Sciences, The Department of Radiation Emergency Medicine, Researcher, 被ばく医療部, 研究員 (20302367)
ANDO Koichi National Institute of Radiological Sciences, Heavy-Ion Radiobiology Research Group, Director, 重粒子医科学センター粒子線生物研究グループ, グループリーダー (00159526)
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| Project Period (FY) |
2004 – 2005
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| Keywords | irradiaton / amylase / salivary gland / tight junction |
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| Research Abstract |
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
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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
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Research Products
(36 results)
