Effects of silica exposure on substance P immunoreactivity and preprotackykinin mRNA expression in trigeminal sensory neurons.
Hunter-DD; Stanley-CF; Dey-RD
FASEB J 1995 Mar; 9(3)(I):A433
Trigeminal sensory neurons innervate the nasal cavity and may release substance P (SP) upon exposure to inhalated irritants. The purpose of this study was to determine if silica dust, an occupational irritant causing inflammation, activates sensory neurons supplying the nasal cavity. Rats were placed in inhalation chambers and exposed daily to 2mg/m3 of fresh silica (<5um) or filtered air for six months (n=3). The trigeminal ganglia (TG) were removed and prepared for SP immunocytochemistry and preprotackykinin (PPT) in situ hybridization. SP-like immunofluorescence in TG neurons was categorized as high, moderate, or low intensity. In situ hybridization autoradiographs were quantified on the basis of grain density using digital imaging analysis. The SP immunoreactivity and PPT mRNA expression in the TG neurons were significantly increased after silica inhalation. The proportion of highly positive SP-immunoreactive neurons shifted from 1.30±.58% in controls to 11.30±1.l5% after silica treatment. The neurons exhibiting high grain density increased from 1.50±.87% in controls to 11.67%±.58 in the silica group. Thus, inhalation of silica results in increased levels of immunoreactive neuronal SP and PPT mRNA. These findings suggest that silica activates sensory pathways which may be involved in nasal inflammation.
Biochemical-analysis; Biochemistry; Biochemistry; Biological-effects; Biological-systems; Cell-biology; Cell-function; Cellular-reactions; Exposure-assessment; Exposure-methods; Immune-reaction; Immune-system; Immunochemistry; Inhalation-studies; Laboratory-animals; Laboratory-techniques; Laboratory-testing; Molecular-biology; Molecular-structure; Nasal-cavity; Nasal-disorders; Neurovascular-disorders; Particle-aerodynamics; Particle-counters; Particulates; Quantitative-analysis
Department of Anatomy and Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV 26506
Abstract; Conference/Symposia Proceedings
The FASEB Journal. Experimental Biology 95 - Annual Meeting of Professional Research Scientists, Atlanta, Georgia, April 9-13, 1995