| Objective To detect the change process of substance P (SP)expression and the difference between fungus and bacterial keratitis and explore effects of SP on the damage and repair process of keratitis model of Wistar ratsMethods Fifty-five healthy Wistar rats were divided into three groups, group A, B and C randomly. Choose the right eye as experiment eye and the left eye as control. Group A was normal group without any treatment including 5 rats. Group B and C, each group including 25 rats, experiment eyes were inoculated with fusarium and staphylococcus respectively. Use physiological saline solution to substitute fusarium and staphylococcus as control. Examine the eye surface everyday after inoculation with slit lamp microscope and scrape tissues from the edge and bottom of ulcer to do Gram stain and 10% potassium hydroxide smear and inoculate them on culture medium 25℃for 3-4 days to determine fungus or bacterial infection.5 rats were executed randomly at 1,5,8,10and 14 days after the surgery. Detailed record and Hematoxylin-Eosin dye were done to each group to examnine the process of ulcer. Expression of SP were detected through immunohistochemistry and reverse transcription polymerase chain reaction.Results 1,Slit lamp microscope:Group B showed gray ulcer and immunological ring after 1day of inoculation. The ulcer increased to peek at 5 days and decreased at 8 days.10days showed new vessels growing into ulcer. After 14days, ulcer changed into vascularized corneal leucoma.Group C showed same change process as group B but without immunological ring. The control eyes showed edema at 1day and recoverd to normal since.2,Hematoxylin-Eosin dye:1day after infection, the cornea of group B showed ulcer with disordered shallow matrix layer collagenous fibre arrangement and neutral granular cell infiltration; after 5 days, ulcer worsened and granular cells infiltrated through the whole layer; after 8 days, ulcer shrinked and fibroblast began to increase with new vessels formed; after 10 days, new vessels began to decrease;after 14days, the matrix level textile fiber assumes scar type restructuring. Grouop C showed similar changes with more inflammatory cells infiltrated.3,Immunohistochemistry:(1)Normal cornea showed mordarate expression of SP in the epithelium while the matrix and endothelium showed weak expression.(2) In group B, epithelium showed increased SP in endothelium cells,inflamatary cells, fibroblast cells and endothelium of new vessels. The expression peeked at 8d, began to decrease at 10d and dropped to lower than normal at 14d, which had significant difference(P<0.05).(3) Grouop C showed similar changes with more SP expression than group B which had significant difference(P<0.05). (4) Controlled eyes showed increased SP expression at 1d and dropped to normal at 5d. There was significant difference between group B, C and controlled eyes(P<0.05).4,Reverse Transcription Polymerase Chain Reaction: The results were consistent with immunohistochemistry examination.Conclusion 1,The expression of SP was consistent with damage at the early stage of ulcer and repair at the late stage, indicating that SP possibly participated in the early time damage and the later period repair process in fungus keratitis.2,The expression in fungus keratitis was lower than the meantime bacterial keratitis, indicating that its lower expression level possibly participated in the mechanism of lighter ache in fungus keratitis.
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