RESUMO
Low-dose-rate radiation modulates various biological responses including carcinogenesis, immunological responses and diabetes. We found that continuous irradiation with low-dose-rate gamma rays ameliorated type II diabetes in db/db mice, diabetic mice that lack leptin receptors. Whole-body exposure of db/db mice to low dose-rate gamma radiation improved glucose clearance without affecting the response to insulin. Histological studies suggested that degeneration of pancreatic islets was significantly suppressed by the radiation. Insulin secretion in response to glucose loading was increased significantly in the irradiated mice. These results suggest that low-dose-rate gamma radiation ameliorates type II diabetes by maintaining insulin secretion, which gradually decreases during the progression of diabetes due to degeneration of pancreatic islets. We also inferred that protection from oxidative damage is involved in the anti-diabetic effect of low-dose-rate gamma rays because expression and activity of pancreatic superoxide dismutase were significantly elevated by low-dose-rate gamma radiation.
Assuntos
Diabetes Mellitus Tipo 2/patologia , Diabetes Mellitus Tipo 2/radioterapia , Raios gama , Animais , Diabetes Mellitus Tipo 2/sangue , Relação Dose-Resposta à Radiação , Feminino , Insulina/sangue , Insulina/metabolismo , Secreção de Insulina , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/patologia , Ilhotas Pancreáticas/efeitos da radiação , Camundongos , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Transcrição Gênica/genéticaRESUMO
This is the first report that rainbow trout (Oncorhynchus mykiss) neutrophils are responsible for non-specific cytotoxicity. A monoclonal antibody (mab) for rainbow trout leucocytes was produced. Using this mab (TTL-5E9), neutrophils (5E9-positive cells) were isolated from the pronephros by a panning technique. The isolated neutrophils showed high viability (approximately 95%) and purity (92-95%), and were functional in cytotoxic activity assays. The neutrophils demonstrated significantly higher cytotoxic activities against YAC-1 target cells than the other cells (5E9-negative cells, predominantly lymphocytes). The number of neutrophils contaminating the 5E9-negative fraction and their non-specific cytotoxicities were positively correlated. These findings demonstrate that rainbow trout neutrophils possess non-specific cytotoxic activities.