ABSTRACT
PURPOSE: The aim of this investigation was to determine whether pre- or post-administration of vitamin A will be effective in reducing the radiation-induced alterations in intestinal disaccharidases in rats. MATERIAL AND METHODS: Rats were subjected to fractionated whole-body irradiation (20 x 0.5 Gy). Intestinal lactase activity as well as maltase and sucrase activities were assessed. Vitamin A was administered at daily intraperitoneal dose of 15,000 IU/kg body weight for 7 days prior to radiotherapy and thereafter twice weekly throughout therapy up to 7 days post irradiation. RESULTS: In irradiated rats a marked decrease in intestinal lactase activity to about one-fourth of those in non-irradiated rats was observed. In addition, a significant reduction in maltase and sucrase activities to one half of the control group was observed. The application of vitamin A significantly improved the radiation-induced inhibition of intestinal enzymes. Pretreatment application of vitamin A is more efficient to protect against radiation injury than a posttreatment application. CONCLUSIONS: The usage of vitamin A for modulation of radiation-induced changes in intestinal enzymes provides sufficient protection against treatment side effects induced by large volume radiotherapy.
Subject(s)
Disaccharidases/radiation effects , Gamma Rays , Intestines/enzymology , Vitamin A/pharmacology , Animals , Disaccharidases/drug effects , Injections, Intraperitoneal , Intestines/drug effects , Intestines/radiation effects , Jejunum/enzymology , Jejunum/radiation effects , Lactase , Male , Radiation Dosage , Rats , Rats, Wistar , Sucrase/metabolism , Sucrase/radiation effects , Vitamin A/administration & dosage , Whole-Body Irradiation , alpha-Glucosidases/metabolism , alpha-Glucosidases/radiation effects , beta-Galactosidase/metabolism , beta-Galactosidase/radiation effectsABSTRACT
It is established that 24 hours after total X-ray irradiation by doses of 0.5, 1 and 2 Gy activity of intestine enzymes (saccharose and alpha-amylase) increases. A dose of 3 and above induces an increase of saccharose activity and inhibition of alpha-amylase. The functional state of basic phosphatase under action of the doses investigated remains practically unchanged.
Subject(s)
Alkaline Phosphatase/radiation effects , Intestines/radiation effects , Sucrase/radiation effects , alpha-Amylases/radiation effects , Alkaline Phosphatase/metabolism , Animals , Intestines/enzymology , Male , Rats , Sucrase/metabolism , alpha-Amylases/metabolismABSTRACT
gamma-Glutamyltranspeptidase (GGT), aminopeptidase N (AP-N), and sucrase in purified rabbit intestinal brush border membrane vesicles were irradiated in situ at -135 degrees C using high energy electrons. Surviving activities of the enzymes were measured as a function of radiation dose, and the functional unit target sizes (corresponding to carbohydrate-free polypeptides) were determined using target analysis. The in situ functional unit sizes were GGT 59 kDa, AP-N 59 kDa, and sucrase 63 kDa. Together with biochemical data determined previously, it is concluded that the noncovalently attached large (approximately 40 kDa) and small (approximately 25 kDa) subunits of GGT are both required for catalytic activity. Furthermore, these data suggest that (i) the membrane-bound form of AP-N consists of one or more noncovalently attached subunits of 59 kDa, each of which is enzymatically active; and (ii) in situ sucrase activity is associated with a subunit of 63 kDa which is noncovalently attached within the sucrase-isomaltase complex.
