Protective effects of Danshen injection against erectile dysfunction via suppression of endoplasmic reticulum stress activation in a streptozotocin-induced diabetic rat model

BACKGROUND: Erectile dysfunction (ED) is a common complication of diabetes. This study aimed to explore the beneficial effect of Danshen injection on ED in a streptozotocin (STZ)-induced diabetic rat model and the underlying mechanism. METHODS: The diabetic rat model was established by an intraperitoneal injection of 60 mg/kg STZ in male Sprague-Dawley rats. The diabetic rats were intraperitoneally injected with Danshen solution (0.5 or 1 mL/kg/day) or the same volume of saline for 6 weeks. Age-matched rats served as controls. After 6 weeks, erectile function and histological morphology of the corpora cavernosum were assessed. Oxidative stress indicators, including superoxide dismutase (SOD) activity, malondialdehyde (MDA) content, and reactive oxygen species (ROS) levels, were measured in penile tissues. The expression levels of glucose-regulated protein 78 (Grp78), growth arrest and DNA damage-inducible gene 153 (GADD153/CHOP) were determined by immunohistochemistry, immunoblotting, and RT-PCR. Apoptosis was detected by a TUNEL assay. RESULTS: The erection times of diabetic rats were significantly less than those of control rats. Danshen injection could improve erectile function via increased erection times. Danshen injection was also found to ameliorate the morphological abnormalities of the corpora cavernosum, to reduce the number of apoptotic cells, and to suppress caspase-3 activation in penile tissue, accompanied by downregulation of the endoplasmic reticulum stress biomarkers Grp78 and CHOP. Danshen injection could increase SOD activity as well as reduce ROS and MDA levels in diabetic rats, indicating suppression of oxidative stress. CONCLUSION: Danshen injection could rescue diabetes-associated ED, possibly via suppressing the oxidative stress and endoplasmic reticulum (ER) stress-induced apoptosis pathways.