Immunohistological Study of the Effects of Intranasal ZnSO4 Instillation on the Mouse Olfactory Epithelium and Olfactory Bulb / 대한이비인후과학회지

ABSTRACT

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate the time course of functional and anatomical recovery of the olfactory epithelium (OE) and olfactory bulb (OB) following intranasal instillation of 1% ZnSO4 in mice. MATERIALS AND METHOD: Two groups of mice, normal control group (intranasal instillation of normal saline, n=6) and experimental group (intranasal instillation of ZnSO4, n=18), were studied. Tissues of olfactory pathways were obtained at 1, 3 and 5 weeks after bilateral intranasal instillation of 1%, 100 microliter ZnSO4 solution, and processed for immunohistochemistry using antisera, olfactory marker protein (OMP), proliferating cell nuclear antigen (PCNA) and tyrosine hydroxylase (TH) to evaluate the olfactory regeneration. For histological study, OE thickness stained with hematoxylin-eosin was analyzed. RESULTS: At 1 week after ZnSO4 intranasal instillation, the lowest peak of OMP expression in OE appeared. Then the number of OMP-positive cells increased progressively at weeks. However, PCNA expression in OE showed quite the opposite. In the corresponding OB at 1 week, there was decrease of TH-positive cells and at 3 weeks, there was few TH-positive cells. At 5 weeks, there was increase in the number of TH-positive cells again. OE thickness was reduced to 20% of control OE at 1 week, and was significantly recovered to 80% of control OE at 5 weeks. CONCLUSION: Our results demonstrated that intranasal instillation of 1% ZnSO4 to mice produces a brief, reversible but essentially complete destruction of functional connection from the olfactory epithelium to the main olfactory bulb.