Mechanism of polysaccharides from Dendrobium huoshanense on streptozotocin-induced diabetic cataract

The functional approach and molecular biological mechanism of polysaccharides from Dendrobium huoshanense C. Z. Tang et S. J. Cheng (Orchidaceae) on anticataract activity were assessed. Rats with intraperitoneal injection of streptozotocin (STZ; 45 mg kg(-1)) were used as the animal model of diabetic cataract. Administration of polysaccharides from Dendrobium huoshanense (HPS) caused a significant body weight increase at dosages of 50, 100, and 200 mg kg(-1) day(-1), whereas blood sugar was decreased. Compared with rats without therapy, the opacity of lenses was abated in groups treated with HPS. Taking into account NO and NOS levels in lenses, 70.2 mu mol mg(-1) protein of NO and 23.4 U mg(-1) protein of NOS were obtained with a dosage of HPS at 200 mg kg(-1)day(-1), which all decreased more than 33% compared with those in the rats without therapy. RT-PCR analysis also showed that the inhibitory response of iNOS gene expression was in a dose-dependent manner with HPS treatment. To restrain advanced glycation end products (AGE) synthesis was another phenomenon in this experiment, and the suppression ratio reached 40.2% at 200 mg kg(-1)day(-1) treatment, compared with the rats without therapy. These results indicated that polysaccharide of D. huoshanense is a new pharmaceutical agent for prevention and cure of diabetic cataract.