Histopathologic assessment of acute dermal exposure to meta-xylene in rats and guinea pigs.
Brinkley-WW; Garrett-CM; Kabbur-MB; Gunasekar-PG; Rogers-JV; Geiss-KT; McDougal-JN
Toxicologist 2001 Mar; 60(1):58
Irritation by organic chemicals and solvents is not well understood due to the complex interplay of multiple, simultaneous molecular interactions leading to acute change. Histopathology provides a valid and verifiable reference point in this changing microenvironment. Rats are often used as experimental animals for the study of toxic mechanisms and guinea pigs are a common species for toxicology tests, which are used to categorize chemicals as skin irritants. The purpose of our study was to compare the time course and severity of the histopathological responses in rats and guinea pigs, so that this could be factored into our choice of species for mechanistic studies. A single topical exposure to xylene resulted in acute dermal inflammation in rats and guinea pigs as early as 2 hours. The dorsal thoracic aspect of male F-344 rats and Hanley Guinea Pigs were exposed to xylene for one hour using Hill Top Chambers. At zero, one, two, four and six hours after exposure skin samples were collected. Light microscopic evaluation was performed on formalin-fixed, routinely processed and paraffin embedded skin sections. Histopathology provides a visual foundation in a changing microenvironment and serves as an anchor for sound explanation of concurrent molecular data. In our acute dermal exposures with xylene, inflammation was more pronounced in guinea pigs than rats. In addition, after one-hour topical xylene exposure, severity in rats and guinea pigs progressively increased in dermal tissues at two, four and six hours. When evaluating granulocyte infiltration, guinea pigs exposed to this irritating solvent respond more rapidly and with greater severity than rats. For selecting a single species for further molecular evaluation however, availability or specificity of antibodies may be a consideration.
Histopathology; Xylenes; Laboratory-animals; Animals; Animal-studies; Organic-chemicals; Solvents; Acute-exposure; Skin-irritants; Exposure-levels; Exposure-assessment; Antibody-response
Disease and Injury: Allergic and Irritant Dermatitis
The Toxicologist. Society of Toxicology 40th Annual Meeting, March 25-29, 2001, San Francisco, California
Wright State University, Dayton, Ohio