Effect of nickel and cadmium chloride on autonomic and behavioral thermoregulation in mice

Male BALB/c mice were injected intraperitoneally (i.p.) with nickel chloride (0, 5, 10, and 15 mg/kg) or cadmium chloride (0, 2, 4, and 6 mg/kg) and preferred ambient temperature (Ta) and activity were measured. Both metals caused marked reductions in preferred Ta and activity within 30 min postinjection. Preferred Ta and activity were depressed for up to 90 min. In a second experiment, body temperature was measured 60 min following the injection of nickel or cadmium chloride at a Ta of 20, 30, or 35 degrees C. Nickel and cadmium caused large reductions in body temperature when injected at a Ta of 20 and 30 degrees C but produced either no effect or only a slight elevation in body temperature at a Ta of 35 degrees C. In a third experiment, metabolic rate was measured continuously for 60 min following an i.p. injection of a relatively large dose of nickel (15 mg/kg) or cadmium chloride (6 mg/kg) at a Ta of 20, 30, and 35 degrees C. Both metals caused significant reductions in metabolic rate at TaS of 20 and 30 degrees C. At a Ta of 35 degrees C, cadmium caused a slight inhibition in metabolic rate while nickel had insignificant effects. These data indicate that nickel and cadmium chloride injected i.p. produce hypothermia by reducing metabolic rate and the preferred Ta.