Nonneoplastic nasal lesions in rats and mice.

Abstract

Rodents are commonly used for inhalation toxicology studies, but until recently the nasal passages have often been overlooked or only superficially examined. The rodent nose is a complex organ in which toxicant-induced lesions may vary, depending on the test compound. A working knowledge of rodent nasal anatomy and histology is essential for the proper evaluation of these responses. Lack of a systematic approach for examining rodent nasal tissue has led to a paucity of information regarding nonneoplastic lesions in the rodent nose. Therefore, slides from the National Toxicology Program (NTP) and the Chemical Industry Institute of Toxicology (CIIT) were examined, and the literature was reviewed to assemble the spectrum of nonneoplastic rodent nasal pathology. Presented are lesions associated with the various types of epithelia lining the rodent nasal cavity plus lesions involving accessory nasal structures. Even though there are anatomic and physiologic differences between the rodent and human nose, both rats and mice provide valuable animal models for the study of nasal epithelial toxicity, following administration of chemical compounds.

Carcinogenicity and Chronic Toxicity in Mice and Rats Exposed by Inhalation to para-Dichlorobenzene for Two Years

“…The respiratory metaplasia of the olfactory epithelium is considered to represent replacement of the affected epithelium with the respiratory-like epithelium in which those epithelial cells showed characteristics of the ciliated and non-ciliated cells of adjacent normal respiratory epithelium. The present microscopic observations of the p-DCB-induced nasal lesions led us to conclude on the basis of the previously reported findings on the nasal cavity of aged animals [29,42] and chemically exposed animals [10,26] that long-term inhalation exposure to p-DCB accelerates the age-related changes in degenerative responses of the nasal cavity to the inhaled toxicant, including the loss of olfactory cells.…”

“…Therefore, the nasal lesions appearing only after the 2-year inhalation exposure to p-DCB were found to be age-related and treatment-related. The eosinophilic globules may reflect a morphological correlate for accumulation of proteinaceous materials in supporting cells of the olfactory epithelium and in ciliated and non-ciliated cells of the respiratory epithelium, since those epithelial cells were reported to release proteinaceous materials [26]. The respiratory metaplasia of the olfactory epithelium is considered to represent replacement of the affected epithelium with the respiratory-like epithelium in which those epithelial cells showed characteristics of the ciliated and non-ciliated cells of adjacent normal respiratory epithelium.…”

Olfactory Epithelial Metaplasia and Hyperplasia in Female Harlan Sprague–Dawley Rats Following Chronic Treatment with Polychlorinated Biphenyls

“…The presence of inflammation within the nasal cavity lumen extending into the mucosa and sometimes to the brain was a prominent feature in these NTP studies. Acute inflammation of the nasal mucosa is a common sequelum of toxic insult, possibly attributable to opportunist infections following enhanced susceptibility due to metaplastic changes and/or atrophy of lymphoid tissue (Monticello et al, 1990). Vol.…”

Deposition Process of Eosinophilic Substance in Mouse Nasal Septum

“…71 (7): [931][932][933][934][935] 2009 An eosinophilic substance (ES) is usually observed in the mouse nasal septum, and its volume increases with age. ES has been described as amyloid in textbooks [5,7], but there are a few descriptions that ES is not amyloid [4,8]. Our previous report revealed that ES is not amyloid because it reacted negatively to Congo red and there were no nonbranching fibrils in the electron microscope examination [1].…”