title: Evidence for stimulatory and inhibitory effects of cadmium on the [3H]thymidine incorporation into various organs of the mouse.
abstract: The effects of cadmium chloride on the DNA turnover in various organs of the mouse were evaluated by measuring the incorporation of intraperitoneally injected [6-3H]thymidine. This approach is considered to be a useful complement to other short-term in vivo tests in the screening for genotoxic properties of chemicals. A moderate amount of CdCl2 (1 mg/kg body wt) lacked inhibitory effects on the incorporation of [3H] thymidine, but produced a significantly increased uptake of the DNA precursor into the liver. Whereas the genotoxic polycyclic aromatic hydrocarbon 3-methylcholanthrene suppressed the [3H]thymidine incorporation into several organs when given in a dose of 30 mg/kg body wt, cadmium chloride was inhibitory only when injected in a sublethal dose (4 mg/kg body wt). When the injected amount of CdCl2 was 4 mg/kg, an initial and transient inhibition of the [3H]thymidine incorporation was observed in several organs. After extending the time between the injection of cadmium and sacrifice to 72 h, such a high dose of cadmium produced potent stimulatory effects on the [3H]thymidine incorporation not only into the liver but also into the pancreas, kidney, small intestine, and testis. The mechanism behind the cadmium-induced stimulation of the DNA synthesis remains obscure but may be due to an increased biosynthesis of the cytoplasmatic protein metallothionein. The stimulatory effects of cadmium on the incorporation of [3H]thymidine correlate well both with reported sites of extensive accumulation of the heavy metal and the presence of high concentrations of cadmium-induced metallothionein.
mesh_terms: D000818:Animals; D002104:Cadmium; D004247:DNA / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D008297:Male; D008748:Methylcholanthrene; D051379:Mice; D008810:Mice, Inbred C57BL; D009928:Organ Specificity; D013936:Thymidine / Q000378:metabolism
chemical_list: D002104:Cadmium; D008748:Methylcholanthrene; D004247:DNA; D013936:Thymidine