Developmental exposure to manganese induces lasting motor and cognitive impairment in rats

Neurotoxicology. 2015 Sep;50:28-37. doi: 10.1016/j.neuro.2015.07.005. Epub 2015 Jul 26.

Abstract

Exposure to high manganese (Mn) levels may damage the basal ganglia, leading to a syndrome analogous to Parkinson's disease, with motor and cognitive impairments. The molecular mechanisms underlying Mn neurotoxicity, particularly during development, still deserve further investigation. Herein, we addressed whether early-life Mn exposure affects motor coordination and cognitive function in adulthood and potential underlying mechanisms. Male Wistar rats were exposed intraperitoneally to saline (control) or MnCl2 (5, 10 or 20 mg/kg/day) from post-natal day (PND) 8-12. Behavioral tests were performed on PND 60-65 and biochemical analysis in the striatum and hippocampus were performed on PND14 or PND70. Rats exposed to Mn (10 and 20 mg/kg) performed significantly worse on the rotarod test than controls indicating motor coordination and balance impairments. The object and social recognition tasks were used to evaluate short-term memory. Rats exposed to the highest Mn dose failed to recognize a familiar object when replaced by a novel object as well as to recognize a familiar juvenile rat after a short period of time. However, Mn did not alter olfactory discrimination ability. In addition, Mn-treated rats displayed decreased levels of non-protein thiols (e.g. glutathione) and increased levels of glial fibrillary acidic protein (GFAP) in the striatum. Moreover, Mn significantly increased hippocampal glutathione peroxidase (GPx) activity. These findings demonstrate that acute low-level exposure to Mn during a critical neurodevelopmental period causes cognitive and motor dysfunctions that last into adulthood, that are accompanied by alterations in antioxidant defense system in both the hippocampus and striatum.

Keywords: Cognition; Development; Manganese; Motor coordination; Neurotoxicity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Animals
  • Animals, Newborn
  • Brain / metabolism
  • Cognition Disorders / chemically induced*
  • Developmental Disabilities / chemically induced*
  • Discrimination, Psychological / drug effects
  • Disease Models, Animal
  • Exploratory Behavior / drug effects
  • Glial Fibrillary Acidic Protein / metabolism
  • Glutathione / metabolism
  • Glutathione Peroxidase / metabolism
  • Glutathione Reductase / metabolism
  • Male
  • Manganese / toxicity*
  • Movement Disorders / etiology*
  • Perceptual Disorders / chemically induced
  • Rats
  • Rats, Wistar
  • Recognition, Psychology / drug effects
  • Smell / drug effects
  • Sulfhydryl Compounds / metabolism

Substances

  • Glial Fibrillary Acidic Protein
  • Sulfhydryl Compounds
  • Manganese
  • Glutathione Peroxidase
  • Glutathione Reductase
  • Glutathione