Authors: Wang Qian, Wan Lei, Li Jing, Zhou Qingjun
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To explore the occurring and developing characteristics of dry eye syndrome in type 1 diabetic mouse model induced with streptozotocin (STZ)-intraperitoneal injection.
Completely randomized design method was performed.Sixty SPF degree male C57BL/6 mice (6-8 weeks old) was randomly divided into diabetic group and control group, which were intraperitoneally injected with citrate buffer and STZ-citrate buffer (50 mg/kg per day), respectively.The average weight, blood glucose level and lacrimal gland weight were examined before injection and 1 month, 2 months, 4 months after the last injection; meanwhile, phenol cotton thread and rose bengal staining methods were used to check tear formation and ocular surface condition; corneal perception meter was used to test corneal sensitivity; periodic acid-schiff (PAS) staining method was used to test the density of conjunctival goblet cells; histopathological staining and Masson staining methods were used to test the tissue changes of lacrimal gland.
Compared with before injections, the body weight and lacrimal gland weight in diabetic group were not significantly changed 1 month, 2 months and 4 months after injection (all at P>0.05), but these measurements in diabetic group 1 month, 2 months and 4 months after injection were significantly lower than those in control group at corresponding time points (all at P<0.05). Compared with before injections and control group at corresponding time points, the blood glucose level were dramatically higher and the tear formation were significantly decreased in diabetic group at 1 month, 2 months, 4 months after injection (all at P<0.05). The ocular surface of diabetic model mice showed positive rose bengal staining 2 months after STZ injections.The corneal sensitivities were significantly lower in diabetic model mice 2 months and 4 months after injection than those before injection and in control group at corresponding time points (all at P<0.05). The density of conjunctival goblet cells in diabetic group 4 months after injection was significantly decreased than those before injection in diabetic group and 4 months after injection in control group (all at P<0.05). The apparent collagen fibrosis and inflammatory cell infiltration were observed at lacrimal gland in diabetic model mice 4 months after injection.
The major early stage manifestations of STZ induced type 1 diabetes mice include retarded growth of lacrimal gland and decreased tear secretion volume, which gradually develop along the course of diabetes; in the later stage, the manifestations include decreased corneal sensitivity, ocular structural damage, structural changes of lacrimal gland and decreased conjunctival goblet cell density.