Duration of airborne-manganese exposure in rhesus monkeys is associated with brain regional changes in biomarkers of neurotoxicity

Keith M. Erikson, David C. Dorman, Lawrence H. Lash, Michael Aschner

Research output: Contribution to journalArticlepeer-review

66 Scopus citations

Abstract

Juvenile (20-24-month-old) rhesus monkeys were exposed to airborne-manganese sulfate (MnSO4) 1.5 mg Mn/m3 (6 h/day, 5 days/week) for 15 or 33 days, or for 65 days followed by a 45 or 90 days post-exposure recovery period, or air. We assessed biochemical endpoints indicative of oxidative stress and excitotoxicity in the cerebellum, frontal cortex, caudate, globus pallidus, olfactory cortex, and putamen. Glutamine synthetase (GS), glutamate transporters (GLT-1 and GLAST) and tyrosine hydroxylase (TH) protein levels, metallothionein (MT), GLT-1, GLAST, TH and GS mRNA levels, and total glutathione (GSH) levels were determined for all brain regions. Exposure to Mn significantly decreased MT mRNA in the caudate (vs. air-exposed controls). This depression persisted at least 90 days post-exposure. In contrast, putamen MT mRNA levels were unaffected by Mn exposure. GLT-1 and GLAST were relatively unaffected by short term Mn exposure, except in the globus pallidus where exposure for 33 days led to decreased protein levels, which persisted after 45 days of recovery for both proteins and 90 days of recovery in the case of GLAST. Exposure to 1.5 mg Mn/m3 caused a significant decrease in GSH levels in the caudate and increased GSH levels in the putamen of monkey exposed for 15 and 33 days with both effects persisting at least 90 days post-exposure. Finally, TH protein levels were significantly lowered in the globus pallidus of the monkeys exposed for 33 days but mRNA levels were significantly increased in this same region. Overall, the nonhuman primate brain responds to airborne Mn in a heterogeneous manner and most alterations in these biomarkers of neurotoxicity are reversible upon cessation of Mn exposure.

Original languageEnglish (US)
Pages (from-to)377-385
Number of pages9
JournalNeurotoxicology
Volume29
Issue number3
DOIs
StatePublished - May 2008
Externally publishedYes

Keywords

  • Air borne
  • Brain
  • Glutamate
  • Glutathione
  • Manganese
  • Monkey

ASJC Scopus subject areas

  • General Neuroscience
  • Toxicology

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