Abstract: Objective To investigate the effect of isorhamnetin on the apoptosis of retinal cells in diabetic retinopathy (DR) rats. Methods The rats were divided into control group, DR model group, low and high dose isorhamnetin groups (ISO-L group, ISO-H group, 50, 150 mg/kg isorhamnetin orally, respectively) and positive drug group (150 mg/kg calcium dobesilate orally). The level of serum inflammatory factors was measured by ELISA; HE staining and TUNEL staining were performed to observe the pathological changes and cell apoptosis of retina. Western blot method was performed to detect protein expression of VEGF, Bax, caspase-3 and phosphorylation levels of p38 MAPK, NF-κB p65 in retinal tissue. Results Compared with the control group, the retina of the model group was arranged disorderly, the boundary was unclear, the inner and outer nuclear layers were edema, the number of cells was reduced, and the thickness of the retina became thinner, and the retinal cell apoptosis rate, serum TNF-α, IL-1β, IL-6 levels, VEGF, Bax, caspase-3 protein expression and p38 MAPK, NF-κB p65 phosphorylation were significantly increased (P＜0.05); Compared with the model group, the retinal tissue layers of the ISO-L, ISO-H, and positive drug groups had clearer boundaries, slightly looser structures, and increased retinal thickness, and the retinal cell apoptosis rate, serum TNF-α, IL-1β, IL-6 levels, VEGF, Bax, caspase-3 protein expression, and p38 MAPK, NF-κB p65 phosphorylation levels were significantly reduced (P＜0.05). Conclusions Isorhamnetin may ameliorate retinal injury and cell apoptosis in DR rats by inhibiting the MAPK/NF-κB signaling pathway.

Key words: isorhamnetin, diabetic retinopathy, retinal tissue, MAPK/NF-κB signaling pathway, cell apoptosis