Metallothionein-I transgenic mice are not protected from gamma-radiation

Metallothionein (MT) has been proposed to play a protective role against th e toxic effects of free radicals and electrophiles, such as those produced by gamma-radiation. Therefore, this study was designed to determine whether MT-transgenic mice, which carry 56 copies of the MT-I transgene and have h igher tissue MT concentrations, are resistant to the toxic effects of gamma -radiation. Mice were exposed to (137)cesium radiation, and survival was fo llowed for 30 days. At all doses (7-12 Gy) examined, no difference in the s urvival was observed between control and MT-transgenic mice. The average su rvival times between control and MT-transgenic mice were also similar. Leuk ocytes were decreased 78 +/- 7% and 75 +/- 11% in control and MT-transgenic mice respectively 5 days after radiation. Furthermore, MT-transgenic mice were also equally susceptible as control mice to the lethal toxic effects p roduced by cyclophosphamide (1.75 mmol/kg, ip). In summary, MT-I transgenic mice are not protected against the toxic effects produced by gamma-radiati on or cyclophosphamide. (C) 1999 Elsevier Science Ireland Ltd. All rights r eserved.