The effect of radiation on endothelin-1 levels of rat brain tissue in early and late periods

Endothelin-1 (ET-1) is a neuropeptide that consisting of 21 amino acids and the most potent vasoconstrictor agent which isolated from porcine aortic endothelial by Yanagisawa et al in 1988. Endothelin is a growth factor on many types of tumor including prostate, ovaries, colon, cervix, breast, kidney, lung, colon cancer and central nervous system. If ionizing radiation passes through a biological matter that interacts with it. During this interaction many physical, physico-chemical, chemical and biological chains occur and as a result of these chains actual biological response seen. Radiation is the most frequently studied carcinogenic. And also, radiation causes tumor progression. An increased production of vasoactive amines like ET-1 in irradiated human endothelial cells in vitro. In this experimental study, we have investigated the effect of ET-1 levels on brain tissues in rats with early and late period after radiation and we have discussed the effect of ET-1 on tumor growth and progression. 4-6 weeks (150-200 gr) of 28 Sprague Dawley rats were used in our study. Rats were divided into 4 groups including the control group, each consisting of 7 rats. This study continued for 30 days of work. 7 Gy of radiation was given to all groups except the control group. Irradiated groups were decapitated 1. day, 7. day and 30. days after radiation and ET-1 levels were studied in irradiated brain tissues. Despite the reduction of ET-1 levels in irradiated brain tissues which obtained in the 1., 7. and 30. days of study when compared with the control group, it is not considered statistically significant because of p>0,05. These groups showed minimal changes in the levels of ET-1 compared with each other. This information also not considered statistically significant because of p>0,05. Consequently, we couldn?t found a significant correlation between ET-1 levels of irradiated brain tissues and effect of radiation in early and late period. This finding showed that no correlation between ET-1 levels and secondary brain tumors or malign transformaiton. Key Words: Endothelin-1, Brain, Radiation, Cancer