Translocation of inhaled ultrafine manganese oxide particles to the central nervous system.

摘要: An important step in assessing the toxicology of particles is to determine their fate after inhalation. Of particular interest us are airborne ultrafine (UFPs; < 100 nm), which abundant ambient urban air and same size as engineered nanoparticles. Translocation extrapulmonary sites respiratory tract deposition represents an mechanism for these cause direct effects secondary target organs (Oberdorster et al. 2005). The extent this process occurs depends on several factors including particle solubility, or aggregate size, site deposition, integrity epithelial lining. UFPs deposit efficiently all regions tract, depending size; specifically, decreases toward smallest UFPs, nasopharyngeal increases (International Committee Radiological Protection 1994). Studies rats have shown translocation soluble manganese compounds from nose along olfactory neuronal pathways bulb (Dorman 2004; Henriksson Tjalve 2000; 1996; 1999) inhalation intranasal instillation exposures. Likewise, few studies that examined deposited nasal mucosa identified route a pathway central nervous system (CNS). These include early non-human primates, demonstrated solid nanosized (30 nm poliovirus; 50 silver-coated gold colloids) axons nerves into (Bodian Howe 1941a, 1941b; DeLorenzo 1970). We also inhaled elemental carbon (13C; 35 nm, count median diameter) accumulate rat whole-body 2004). Regarding penetration deeper brain regions, (1995) ionic Mn instilled chamber pike has ability pass synaptic junctions migrate more distal hypothalamus. Dorman (2004) found striatum cerebellum subchronic exposure salt (sulfate); however, was attributed uptake blood. Thus, contributions levels blood need be considered may issue UFPs. The translocated determine. For example, preliminary information emerged populations welders some them develop parkinsonism 17 years earlier than general population (Racette 2001). Welding produces high amounts fumes containing (Zimmer 2002). Several recent epidemiologic describe occupational ranges approximately 0.01–5 mg/m3 various welding processes materials (Korczynski Li Sinczuk-Walczak Conflicting data emerge animal studies, regarding brain. (2000) reported changes glial fibrillary acidic protein (GFAP) S-100b, markers astrocyte activation, exposed intranasally chloride. However, did not find any evidence GFAP sulfate phosphate. Potential contributing lack concurrence results differences solubilities salts used, doses, contribution damage. In present study, we sought address hypothesis major poorly oxide deposits CNS. characterized oxidation state, vitro solubility gas-phase–generated compared kinetics MnCl2 were applied epithelium via instillation. then measured accumulation lung, liver, repeated exposures with both nares patent one naris occluded. show retained (ipsilateral only) exposure-induced region demonstrate importance processes.