Objective:Tostudy the feasibility of making animal model ofamyotrophic lateral sclerosis usinglowdose chronic cadmium poisoning method in rats.Methods:Adult SD rats were treated with cadmium chloride(150mg/L)by drinking for 120 days.Motor nerve conduction velocity

the morphologieal changes of musculus biceps femoris and spinal motor neuron were studied with electrophysiolog-ical technique

light and electron microscopy.The content of cadmium in the spinal cord

the active change of CuZn-SOD1 and MDA were measured with the atomic absorption and biochemistry techniques .Results:120 days after the cadmium(Cd)treatment in rats

the motor nerve conduction velocity were slowdown in the Cd group.However

no obvious change was found in the muscle fiber diameter between Cd and control group.The mean cross-sectional areas of spinal motorneurons were decreased and the degranulation of ribosomes were found in some motorneurons.The content of Cd in spinal cord increased significantly after Cd exposure.The enzymatic activity of CuZn-SOD1 was weak and the content of MDA increased in Cd group.Conclusion:Chronic low dose Cd exposure can deposit in the spinal cord of adult rats.It may cause functional change in spinal motorneurons and motor nerve fibers

which can be the method to make the animal model of amyotrophic lateral sclerosis.