Abstract
Any of physical, chemical or biological stressors can induce metallothionein (MT) synthesis in animals. A striking resistance to lethal damage from a 6-8 Gy radiation has been found in mice received various stressful pretreatments to induce MT in liver prior to irradiation.In the livers of the mice subjected to these pretreatments (e.g.injection of MnCl2 20mg Mn/kg or dermal excision of 2x2 cm2etc.), MT synthesis increased 5-7 fold (Matsubara et al. Radiat. Res. 1987).Firstly we confirmed that MT can act as a substitute of glutathione in NADPH-glutathione-reductase system in vitro. Secondly we measured the levels of organic radicals in the livers of the pretreated mice(Miyazaki et al.Radiat.Phys.Chem.1996). Since MT is a cystein-rich protein it can be a radical scavenger.It was found that the increased level of MT accelerates the scavenging organic radicals, having a half-life of about 10 hrs in the control and 1.5-3hrs in the pretreated ones so that gross levels of the radicals are kept constant in the liver even at the load of various stressors to the body. [J Radiat Res 44:380 (2003)]
