The Importance of the Diluent for Airway Transport of Toluene Diisocyanate Following Intranasal Dosing of Mice

Abstract

Uncertainty of the transport of reactive chemicals to the lung is a major concern when using intranasal dosing of animals. In a preliminary study using mice, intranasal instillation of the dyes methylene blue (in water) and Sudan black B (in 1:4 ethyl acetate:olive oil), indicated that the following conditions were necessary to achieve transport to the lung: (1) aqueous diluent, (2) light anesthesia prior to dosing, (3) holding the animal in a supine position during chemical application, and (4) maintaining the animal in the same position postdosing. Using these conditions, we investigated the distribution of toluene diisocyanate (TDI), a major industrial asthmogen, to the lung following intranasal administration. Female C57BL/6 mice received 20 microl of 1% TDI in ethyl acetate:olive oil (1:4). Group 1 received a single application on day 1; group 2, single applications on 2 consecutive days; group 3, single applications on 4 consecutive days; and group 4, a single application of the vehicle on 2 consecutive days. All mice were necropsied 24 h after the final application. The nasal passages, upper pharynx, trachea, lungs, and olfactory bulbs of each animal were examined with hematoxylin-eosin and immunohistochemical staining, the latter using a rabbit anti-TDI antiserum. Histopathology revealed desquamation of ciliated epithelial cells as well as inflammatory cell debris in the nasal cavity and upper pharynx of animals in groups 1-3. The intensity of these changes was dependent on the number of applications. No inflammation was observed in the trachea, lungs, or olfactory bulbs in any of the groups. Immunohistochemical examination revealed positive staining for the TDI moiety in epithelial cells of the nasal cavity and upper pharynx in animals of groups 1-3. No staining was observed in the trachea, lungs, or olfactory bulbs of any animal. These results suggest that TDI, when dissolved in olive oil:ethyl acetate and applied intranasally, does not reach the trachea and/or lower airways.

Oropharyngeal aspiration: An alternative route for challenging in a mouse model of chemical-induced asthma

“…A disadvantage, however, is that the distribution between the upper and lower respiratory tracts is heavily influenced by 0300-483X/$ -see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.tox.2009.02.007 the instilled volume, the degree of anesthesia and the nature of the vehicle in which the allergens are dissolved (aqueous or nonaqueous) (Ebino et al, 1999;Southam et al, 2002). Oropharyngeal aspiration has been proposed as an alternative to intratracheal instillation because it does not have the drawbacks of the latter.…”

Local Effects on Airway Inflammation and Systemic Uptake of 5 nm PEGylated and Citrated Gold Nanoparticles in Asthmatic Mice

“…A main objective of this study was to evaluate the local effects of nanoparticles on the airways in the context of asthma, so the effect of intranasal nanoparticle treatment was compared between asthma and nonasthma groups. The intranasal route of administration was chosen because it is less invasive but similarly effective as intratracheal application . The asthma groups treated with pbs, citrated (citrate/tannic‐acid‐coated) gold nanoparticles, and PEGylated gold nanoparticles were all significantly different.…”

Glutathione-conjugated toluene diisocyanate causes airway inflammation in sensitised mice

“…We administered a GS-TDI conjugate containing 150 lg TDI in saline intratracheally instead of 243 lg of ''free'' TDI in ethyl acetate/olive oil intranasally. Interestingly, Ebino et al (1999) demonstrated that intranasal application of TDI in ethyl acetate/olive oil did not reach the lower airways. Therefore, the applied oily vehicle used by Scheerens et al (1996) may explain the observed lack of lower airway inflammation.…”