Microglial and astroglial reaction in the olfactory bulb of mice after Triton X-100 application

Abstract

Gliosis including microgliosis and astrogliosis is a response to central nervous system inflammation. The purpose of this study was to evaluate whether olfactory bulbs are influenced by intranasal exposure to the detergent Triton X-100, a non-ionic surfactant. In this experiment, we measured olfactory function in mice based on the time needed to identify hidden pellets. Our results found that more time was needed to find the buried pellets by mice exposed to Triton X-100 compared with mice without Triton X-100 exposure, up to day 7. Histopathological examination revealed inflammatory cells in the olfactory mucosa and olfactory bulbs in mice treated with Triton X-100. Western blot analysis revealed significant downregulation of olfactory marker proteins in the olfactory mucosa and bulbs of mice after intranasal exposure to Triton X-100. In the olfactory bulbs of mice exposed to Triton X-100, microgliosis and astrogliosis were evident using immunohistochemistry. Cathepsin D was also upregulated in Iba-1-positive microglia/macrophages and GFAP-positive astrocytes in the olfactory bulbs of mice exposed to Triton X-100. In mice, Triton X-100 induced olfactory sensory neuron death in the nasal cavity and gliosis in olfactory bulbs with concurrent downregulation of olfactory marker protein expression, resulting in transient olfactory dysfunction.

Keywords: Cathepsin D; Gliosis; Olfactory bulb; Olfactory marker protein; Triton X-100.