AIM: To apply different doses of polygona-polysaccharose(PSP)to diabetic rats model by gastrogavage that were induced by streptozotocin(STZ), then check the rats about anterior segment, F-VEP, ERG, fundus fluorescein angiography(FFA)and measure fasting blood glucose(glucose oxidase method)by inner canthus vein blood to observe the eye disease process at different time points and to discuss the protective effect of PSP on ocular lesions in DM rats and the treatment effect, to provide the experimental basis and theoretical basis for PSP treating diabetic ocular disease.

METHODS: One hundred male SD rats were randomly divided into 2 groups: diabetic model group(80 rats induced by STZ)and blank control group(20 rats). Then the diabetic model group was randomly divided into 4 subgroups. The group DM(diabetic group)had 20 rats with normal diet and 2mL physiological saline for daily gavage. PSP gavaged groups included three subgroups and with 20 rats in each group, group L(low dose of PSP gavage group, 200mg/kg), group M(medium dose of PSP gavage group, 400mg/kg), group H(high dose of PSP gavage group, 800mg/kg). Every group was gavaged with 2mL PSP. Twenty rats in group BC(blank control group), and they were gavaged saline of equal dose as control. After the success of modeling, 5 groups were under the same conditions of feeding, and gavaged every day. At 2, 4, 6, 8, 10 and 12wk, anterior segment examination and FFA were given. At 4, 8 and 12wk, F-VEP and ERG were given. Fasting blood glucose(by glucose oxidase method)was measured through inner canthus vein blood.

RESULTS: Compared to BC group, fasting blood glucose levels were significantly higher in group DM, L, M and H(P<0.05). Compared to DM group, fasting blood glucose level decreased in L, M, H group(P<0.05). The fasting blood glucose levels of L, M and H groups showed a time and dose dependent relationship. After anterior segment examination, there were 6 rates in DM group, 3 in L group, 1 in M group with different degrees of cataract symptoms which became more serious with time. The BC group was not found any abnormal in the anterior segment. Examined by F-VEP, the rats in group DM showed extension of the P100 peak latency. Compared to the group DM, PSP gavaged group showed a shortened of the extension of the P100 peak latency, while the group BC had no obvious change. In the ERG examination, the rats in group DM showed that amplitude of Max-R a, b wave decreased by 51.2%, 59.8% and amplitude of Cone-R a, b wave decreased by 31.4%, 41.2%. The Ops OS value and amplitude of 30Hz Flicker N1-P1 decreased, there was a significant difference compared to group BC. PSP gavaged group was better than group DM. In the FFA examination, in group DM, we could find the typical manifestations of diabetic retinopathy background fluorescence enhancement, distortion of the blood vessels and blood capillary dilate, retinal vascular leakage of fluorescein and intraretinal hemmorhages compared with the group BC. PSP gavaged group was better than group DM.

CONCLUSION: PSP can effectively reduce the blood glucose levels of diabetic rats,and also can delay the process of ocular complications in diabetic rats, which have an obvious therapeutic effect on ocular lesions. The mechanism is likely to improve the metabolism of glucose and lipid metabolism, increase the amount of glucose tolerance, and play a protective role in diabetic lens metabolism and retinal microvascular disease.