OBJECTIVETo study the reactive changes of normal nasal mucosa in rabbit under photodynamic therapy (PDT) and to make a preliminary research for the treatment of allergic rhinitis (AR) with PDT.

METHODSTwenty-four New Zealand rabbits were divided into 2 groups, an experimental group and a control group with 12 rabbits in each group. PDT was applied to the experimental group, while the control group was given no treatment. The nasal mucosa was sampled separately from the same position of the rabbits from the 2 groups on 1st, 3rd, 7th, 14th, 21st, 28th day. Histomorphological changes of the sampled nasal mucosa were observed under light microscope and transmission electron microscope (TEM). The damage of three tachykinins: substance P (SP), neurokinin A (NKA) and neurokinin B (NKB) of nerve fibers was observed after immunohistochemical staining.

RESULTSCompared with the control group, the nasal mucosa tissues from the experimental group had serious inflammatory reaction with basal layer damaged on the 1st and 3rd day after PDT application, the epithelial cells of nasal mucosa were arranged in disorder, and part of cilium shortened and became abnormal or even disappeared, each organelles damaged obviously; on the 7th, 14th, 21st day, it could be seen that ciliated cell, columnar cell and goblet cell started regeneration, basal cell and lamina propria glands proliferated, and the glands appeared secretion phenomenon; on the 28th day, ciliated columnar epithelium took back the nasal mucosas with small amount of microvilli, and mucous granules were found in the column cells. Nasal immunohistochemical staining of the experimental group from various stages showed that three kinds of neuropeptides were not expressed.

CONCLUSIONSNormal rabbit nasal mucosas will be temporarily damaged after PDT application, the damaged nasal mucosa begin to recover in one week, and return to normal in about four weeks. Most structure and functions have recovered at the fourth week except some nerve endings.