The neuroprotection of somatostatin and its effects on the expression of GFAP and synaptophysin in rats with diabetic retinopathy

Abstract

Objective To investigate the neuroprotective effects of somatostatin and its effects on the expression of glial fibrillary acidic protein (GFAP) and synaptophysin(SYN) in rats with diabetic retinopathy. Methods A total of 24 clean male Sprague-Dawley(SD) rats were divided into control group, diabetic group and somatostatin treatment group according to random number table, with 8 rats in each group. Diabetes was induced by streptozotocin in diabetic group and somatostatin treatment group. After diabetes was induced, rats in somatostatin treatment group were given somatostatin (10 μg·kg-1·d-1) by intraperitoneal injection. Rats in control group and diabetic group were given the equal dose of saline. After 12 weeks, the density of retinal ganglion cells(RGC) were detected by HE staining; the expression of retinal GFAP and SYN were detected by immunofluorescence and Western blotting. Results Compared with control group, the fluorescence intensity of GFAP was significantly increased while the RGC density and the fluorescence intensity of SYN were decreased significantly. The expression of GFAP protein were increased and the expression of SYN protein was decreased in diabetic group compared with control group (F=187.62, 226.12, 159.30, 259.09, 425.93, all P<0.01). Compared with diabetic group, the fluorescence intensity of GFAP was decreased significantly while the RGC density and the fluorescence intensity of SYN were increased significantly. The expression of GFAP was decreased and the expression of SYN was increased in somatostatin treatment group compared with diabetic group (F=187.62, 226.12, 159.30, 259.09, 425.93, all P<0.01). Conclusion Somatostatin may increase the expression of SYN and restore the density of RGC by inhibiting the activation of glial cells, which suggests that somatostatin may play a neuroprotective role in diabetic retinopathy. Key words: Somatostatin; Diabetic retinopathy; Neuroprotection; Glial fibrillary acidic protein; Synaptophysin