Microstructural changes of olfactory mucosa in rat model with acute rhinosinusitis leading to olfactory dysfunction

Abstract

To observe the microstructural changes of olfactory mucosa in rat model with acute rhinosinusitis leading to olfactory dysfunction, and to provide foundation for further exploration of corresponding mechanism. On the basis of prior successfully established rat model of acute rhinosinusitis through inoculation with Streptococcus pneumoniae and with the help of merocel strips, one hundred healthy SD rats were randomly divided into experimental group (80) and control group (20). After inoculation, every 20 rats in the experimental groups were sacrificed in first week, second week, third week and fourth week respectively; and all rats in the control group were sacrificed in first week after the inoculation. Before the rats were sacrificed, the method called "buffed food pellet test, BFPT" was adopted, which was advanced by professor Nathan, to measure the rats' olfaction,and the time of every rat spending in finding out the food pellet was recorded and analyzed. BFPT showed that the rats in experimental group spent (402.9 ± 9.3), (453.7 ± 7.3), (351.9 ± 8.9), (278.7 ± 8.1) s respectively in searching the food pellet, which were more than the rats in the control group [(178.3 ± 6.6) s]. Then the olfactory mucosa was collected under anatomic microscope from all the rats to make frozen section and detect the changes of mature olfactory receptor neurons (ORN) and olfactory ensheathing cells (OEC) by immunofluorescence technique. The reduction of ORN in various degrees could be detected in the tissue samples of olfactory mucosa among all the rats in experimental group, with a tendency to become thinner in the thickness of epithelial lamina during the inflammation developing course. This kind of pathology was most marked in the second week and it gradually developed into the stage showing the lesion being the feeblest in the forth week following the beginning of modeling. Although the number of olfactory ensheathing cells appeared reduction in the first week following the beginning of modeling as well,it came to increase from the second week before olfactory receptor neurons and almost completely recovered to normal in the fourth week. In addition, some olfactory ensheathing cells could be detected in the tissue samples of olfactory mucosa among all the rats in experimental group. Both mature olfactory sensory neurons and olfactory ensheathing cells appeared to reduction when sinonasal mucosa taken place acute rhinosinusitis. But the number of olfactory ensheathing cells increased faster than olfactory sensory neurons. In addition, some olfactory ensheathing cells could be detected in the olfactory epithelium.