Craniofacial and olfactory sensory changes after long-term unilateral nasal obstruction—an animal study using MMP-3-LUC transgenic rats

TL;DR

Long-term nasal blockage in rats causes changes in facial structure and olfactory function, as shown through imaging and protein analysis.

Contribution

This study reveals craniofacial and olfactory changes due to long-term nasal obstruction using MMP-3-LUC transgenic rats.

Findings

Unilateral nasal obstruction reduced MMP-3 signals in the nasal region of transgenic rats.

Long-term obstruction caused nasal septal deviation and increased maxillary molar dental height.

Compensatory growth in olfactory nerve bundles and epithelium was observed.

Abstract

Nasal obstruction exerts considerable physiological effects on the respiratory system and craniofacial morphology during the developmental stage. This study used MMP-3-LUC transgenic rats for in vivo tracking of long-term expression in the rat nasal region after unilateral nasal obstruction. Skeletal changes of the craniofacial, nasal, and sinus regions were measured through micro-computed tomography examination and analysis with 3D image processing and calculation. Matrix metalloproteinase-3 and olfactory marker protein expression were also investigated through immunohistochemistry (IHC). Unilateral nasal obstruction significantly reduced the MMP-3 signal in the nasal region of MMP-3-LUC transgenic rats, which was mainly expressed in the respiratory epithelium. Long-term obstruction also caused morphological changes of the craniofacial hard tissue, such as nasal septal deviation, longer inter-jaw distance, and increased maxillary molar dental height. It also caused compensatory growth in olfactory nerve bundles and the olfactory epithelium, as confirmed by IHC. In our study, long-term unilateral nasal obstruction caused nasal septal deviation toward the unobstructed side, hyper divergent facial development including longer molar dental height, and reduced MMP-3 production. However, further investigation is necessary to explore the mechanism in depth.

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