Tissue manganese concentrations in lactating rats and their offspring following combined in utero and lactation exposure to inhaled manganese sulfate.

There is little information regarding the tissue distribution of manganese in neonates following inhalation. This study determined tissue manganese concentrations in lactating CD rats and their offspring following manganese sulfate (MnSO4) aerosol inhalation. Except for the period of parturition, dams and their offspring were exposed to air or MnSO4 (0.05, 0.5, or 1 mg Mn/m3) for 6 h/day, 7 days/week starting 28 days prior to breeding through postnatal day (PND) 18. Despite increased manganese concentrations in several maternal tissues, MnSO4 inhalation exposure did not affect body weight gain, terminal (PND 18) body weight, or organ weights in the dams. Exposure to MnSO4 at 1 mg Mn/m3 resulted in decreased pup body weights on PND 19 and decreased brain weights in some PND 14 to PND 45 pups. Exposure to MnSO4 at > or =0.05 mg Mn/m3 was associated with increased stomach content, blood, liver, and skull cap manganese concentrations in PND 1 pups, increased brain, lung, and femur manganese concentrations in PND 14 pups, and elevated olfactory bulb, cerebellum, and striatum manganese concentrations in PND 19 pups. When compared to controls, MnSO4 exposure to > or =0.5 mg Mn/m3 increased liver and blood manganese concentrations in PND 14 pups and increased liver, pancreas, and femur manganese concentrations in PND 19 pups. Manganese concentrations returned to control values in all offspring tissues by PND 45 +/- 1. Our data demonstrate that neonatal tissue manganese concentrations observed following MnSO4 inhalation are dependent on the MnSO4 exposure concentration and the age of the animal.