Development of methodology for the three-dimensional modelling of the metabolic capacity of the rat nasal cavity using glutathione S-transferase M1 as an example

[Nasal-air conditioning]

INTRODUCTION

We present a review of nasal-air conditioning, a process essential to undisturbed gas exchange and cleansing of the respiratory mucosa in the nose.

METHODS

A selective literature review was made on the basis of in vivo measurements and computer simulation of the upper airways as well as the authors' own clinical and experimental data.

RESULTS AND DISCUSSION

Healthy subjects normally breathe through the nose, although the nasal airways have significantly higher airway resistance compared to the oral cavity, which is opened for breathing during exercise, in the case of nasal airway blockage, or in allergic rhinitis. In addition to olfaction, the main tasks of nasal breathing include: cleansing, defense, and conditioning (i.e., humidification and heating). The current knowledge of nasal conditioning processes will be discussed. In addition, research activities of particular relevance for diagnosis and intervention in various pathologies of the upper airways will be presented.

Zonal expression and activity of glutathione S-transferase enzymes in the mouse olfactory mucosa

The rodent olfactory mucosa is characterized by a mosaic of gene expression that is exhibited among various cell types. Olfactory sensitivity in these animals is conveyed through odorant receptor families that are distinctly expressed within various subsets of the olfactory neuron population. Receptor neurons that express a particular class of odorant receptors exhibit bilaterally symmetric zones, which generally define their location within the nasal cavity. Less characterized are zonal expression profiles of proteins among non-neuronal cell types of the olfactory mucosa. In this study, we survey the expression of three glutathione S-transferase (GST) isozymes (alpha, mu, and pi) in the mouse olfactory mucosa and characterize the zonal expression of the mu isozyme. Immunohistochemistry and Western blot analysis of the GST mu isozyme reveal that the lateral olfactory turbinates I, Ib, II, IIb, and III display a greater intensity of expression for GST mu, in comparison to the dorsal and septal regions of the mucosa. GST alpha and pi isozymes do not display any distinct zonal organization in olfactory tissue of the adult mouse. When the general substrate 1-chloro-2-4-dinitrobenzene (CDNB) was used to assess GST activity within the olfactory tissue, the lateral turbinate regions displayed a higher level of activity when compared to dorsal or septal regions. Analysis of GST mu expression in prenatal and early postnatal olfactory tissue also reveals a zonal expression of the isozyme. We relate the significance of these findings to metabolic topography and olfactory chemosensory function.