Bioaccumulation and locomotor effect of manganese dust in rats

The primary goal of this study is to determine the effects of Mn exposure v ia inhalation. The bioaccumulation of Mn in different organs and tissues, t he alteration of biochemical parameters, and the locomotor activity were as sessed. A group of 26 male Sprague-Dawley rats (E) were exposed to 3750 mug /m(3) of Mn dust for 6 h/day, 5 days/wk for 13 consecutive weeks and compar ed to a control group of 12 rats (C) exposed to 4 mug/m(3). After exposure, neurological evaluation was carried out for 36 h ( a night-day-night cycle ) using a computerized autotrack system. Rats were then sacrificed by exsan guination, and Mn content in organs and tissues was determined by neutron a ctivation analysis. Mn concentrations in lung, putamen, and cerebellum were significantly higher in E than in C (0.30 vs. 0.17, 0.89 vs. 0.44, 0.63 vs . 0.48 ppm; p < .01), as well as in the kidney, frontal cortex, and globus pallidus ( 1.15 vs. 0.96, 0.84 vs. 0.47, 1.28 vs. 0.55 ppm; p < .05). Potas sium concentration was significantly lower in E than in C (5.11 vs. 5.79 mm ol/L; p < .05), as was alkaline phosphatase (106.9 vs. 129.6 U/L; p < .01). Locomotor activity indicated higher distance covered in the first 12-h per iod for E (45 383 vs. 36 098 cm; p < .05) and lower resting time in the las t 12-h period for E ( 36 326 vs. 37 393 s; p < .05). This study is the firs t of several ongoing studies in our laboratory that address health concerns associated with inhalation exposure to different Mn species and to differe nt levels of exposure.