Abstract: Objective To investigate the effect and its mechanism of total triterpenoids in guava leaves (TTPGL) on retina injury in diabetic rats. Methods The diabetes mellitus (DM) rat model was induced by intraperitoneal injection (IP) of streptozotocin (STZ, 55 mg/kg) in fifty male rats. After the model was induced successfully, the rats were numbered and divided into 5 groups according to the random number table method: diabetes group (DM group, intragastric administration of normal saline), TTPGL low-dose group (TTPGL-L group, 50 mg/kg intragastric administration), TTPGL medium-dose group (TTPGL-M group, 100 mg/kg intragastric administration), TTPGL high-dose group (TTPGL-H group, 200 mg/kg intragastric administration) and metformin group (Met group, 10 mg/kg, intragastric administration, positive control). Ten normal male SD rats were taken as control group (CON group, intragastric administration with normal saline). After twelve weeks, the expression of glial fibrillary acidic protein (GFAP), NF-κB and TNF-α in retina were detected by immunofluorescence or Western blot assay, and the density of RGC was detected by HE staining. Results After 12 weeks of intervention, compared with CON group, the blood glucose, the protein expression levels of GFAP, NF-κB and TNF-α were significantly higher, and the density of RGC was significantly lower in DM group (all P＜0.05). Compared with DM group, the protein expression levels of GFAP, NF-κB and TNF-α were decreased significantly, the density of RGC was increased significantly in TTPGL-M group, TTPGL-H group and Met group (all P＜0.05). There were no significant differences in the above indexes between DM group and TTPGL-L group (P＞0.05). Conclusion TTPGL has protective effect on RGC injury in diabetes state, and its mechanism may be related to the lowering blood glucose, down-regulating the expression of GFAP in retina and inhibiting inflammatory reaction.

Key words: diabetic retinopathy, rats, Sprague-Dawley, retinal ganglion cells, glial fibrillary acidic protein, NF-kappa B, tumor necrosis factor-alpha, total triterpenoids in guava leaves