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. 2017 Jan;242(1):92-101.
doi: 10.1177/1535370216663866. Epub 2016 Aug 9.

Original Research: Potential Ocular Protection and Dynamic Observation of Polygonatum Sibiricum Polysaccharide Against Streptozocin-Induced Diabetic Rats' Model

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Free PMC article

Original Research: Potential Ocular Protection and Dynamic Observation of Polygonatum Sibiricum Polysaccharide Against Streptozocin-Induced Diabetic Rats' Model

Yi Wang et al. Exp Biol Med (Maywood). .
Free PMC article

Abstract

Ocular complications associated with diabetes mellitus are progressive and becoming one of the most important causes of morbidity worldwide. The purpose of the study is to evaluate the protective effect of Polygonatum sibiricum polysaccharide, an important component of Polygonatum sibiricum, on ocular complications in streptozotocin-induced diabetes mellitus rats. Sprague Dawley rats were made diabetic with streptozotocin(60 mg/kg, i.v.) and then the rats were treated with Polygonatum sibiricum polysaccharide 200, 400 and 800 mg/kg.d by gavage for 12 weeks. Biochemical analysis indicated that Polygonatum sibiricum polysaccharide lowered the levels of fasting blood glucose and glycated hemoglobin in blood and elevated the levels of insulin and C-peptide in plasma of diabetes mellitus rats in a dose-dependent manner. Physical measurements revealed that Polygonatum sibiricum polysaccharide improved clinical symptoms of polydipsia, polyphagia, polyuria and weight loss in diabetes mellitus rats. The content of malondialdehyde and activity of superoxide dismutase in plasma were determined, and the data showed Polygonatum sibiricum polysaccharide suppressed oxidative stress reaction. Lens opacification was observed using slit lamp illumination, and the data showed Polygonatum sibiricum polysaccharide delayed cataract progression in a dose-dependent manner. Electroretinogram showed Polygonatum sibiricum polysaccharide treatment reversed the decrease of electroretinogram b and OPs2 waves' amplitudes. Flash-visual evoked potential test indicated that the peak time of P2 wave was prolonged, and the amplitude of N2-P2 was lowered in diabetes mellitus group, and Polygonatum sibiricum polysaccharide suppressed these changes. Fundus fluorescein angiography showed Polygonatum sibiricum polysaccharide alleviated the retinal vasculopathy in a dose-dependent manner. In conclusion, these results suggest that the administration of Polygonatum sibiricum polysaccharide slows the progression of diabetic retinopathy and cataract through alleviating hyperglycemia and reducing oxidative stress in streptozotocin-induced diabetes mellitus rats.

Keywords: Polygonatum sibiricum polysaccharide; cataract; diabetes mellitus; diabetic retinopathy; ocular complications.

Figures

Figure 1
Figure 1
PSP lowered the levels of FBG and HbA1c and elevated the levels of INS and C-peptide in DM rats. Data are presented as mean ± SD of 14–16 animals. (a) Showing FBG level of every group during the intervention period. Compared with that of BC group, FBG level of DM group was promoted by more than twice after STZ injection (P < 0.001) and continued to elevate throughout the experimental period. Compared with DM group, middle dosage and high dosage of PSP downregulated FBG level at every experimental time starting from first week (P < 0.01); low dosage of PSP downregulated FBG level as well (P < 0.01or P < 0.05) during experiment (period except for fifth and sixth weeks). (b) Showing HbA1c level of every group during the intervention period. Compared with that of BC group, HbA1c was significantly higher in DM group (P < 0.001). Compared with DM group, HbA1c level of PSP-H group became lower at fourth week (P < 0.05); HbA1c level of PSP-M and PSP-H groups became lower at eighth week (P < 0.01); HbA1c level of PSP-L, PSP-M and PSP-H groups became lower at 12th week (P < 0.01). (c) Showing INS level of every group during the intervention period. Compared with that of BC group, induction of DM resulted in a distinct reduction of ISN (P < 0.001). Compared with DM group, INS level of PSP-L, PSP-M and PSP-H groups was increased at fourth week (P < 0.01); INS level of PSP-H group was increased at 8th and 12th weeks (P < 0.05). (d) Showing C-peptide level of every group during the intervention period. Compared with that of BC group, C-peptide level in plasma of DM group was remarkably decreased (P < 0.001) Compared with DM group, C-peptide level of PSP-L, PSP-M and PSP-H groups was increased at 12th week (P < 0.05 or P < 0.01). INS: insulin; FBG: fasting blood glucose; HbA1c: glycated hemoglobin
Figure 2
Figure 2
PSP attenuated oxidative stress in STZ-induced DM rats. (a) Showing the content of MDA in plasma during the intervention period. (b) Showing the activity of SOD in plasma during the intervention period. Data are presented as mean ± SD of 14–16 animals. ##P < 0.01 vs. BC group; *P < 0.05, **P < 0.01 vs. DM group. MDA: malondialdehyde; SOD: superoxide dismutase; BC: blank control; DM: diabetes mellitus; PSP-H: Polygonatum sibiricum polysaccharide high; PSP-L: Polygonatum sibiricum polysaccharide low; PSP-M: Polygonatum sibiricum polysaccharide middle
Figure 3
Figure 3
PSP had anticataract effect on STZ-induced DM rats. After dilating the pupils of animals with 1% tropicamide, lens opacification was observed using slit lamp illumination. This figure shows the representative photos from each group during the intervention period. Cataract in DM group developed rapidly, while those in PSP groups progressed slowly in a dose-dependent manner. (A color version of this figure is available in the online journal.) BC: blank control; DM: diabetes mellitus; PSP-H: Polygonatum sibiricum polysaccharide high; PSP-L: Polygonatum sibiricum polysaccharide low; PSP-M: Polygonatum sibiricum polysaccharide middle
Figure 4
Figure 4
Effect of PSP on ECG of DM rats. Full-field ERG was performed using eye electrophysiological diagnosis system. (a) Showing peak time of ERG b wave. (b) Showing amplitude of ERG b wave. (c) Showing peak time of ERG OPs2 wave. (d) Showing amplitude of ERG OPs2 wave. Data are presented as mean ± SD of 14–16 animals. ##P < 0.01 vs. BC group; *P < 0.05, **P < 0.01 vs. DM group. BC: blank control; DM: diabetes mellitus; PSP-H: Polygonatum sibiricum polysaccharide high; PSP-L: Polygonatum sibiricum polysaccharide low; PSP-M: Polygonatum sibiricum polysaccharide middle
Figure 5
Figure 5
Effect of PSP on F-VEP of DM rats. F-VEP was recorded using eye electrophysiological diagnosis system. (a) Showing peak time of F-VEP P2 wave. (b) Showing amplitude of N2-P2 wave. Data are presented as mean ± SD of 14–16 animals. #P < 0.05, ##P < 0.01 vs. BC group; *P < 0.05 vs. DM group. BC: blank control; DM: diabetes mellitus; PSP-H: Polygonatum sibiricum polysaccharide high; PSP-L: Polygonatum sibiricum polysaccharide low; PSP-M: Polygonatum sibiricum polysaccharide middle
Figure 6
Figure 6
Effect of PSP on FFA of DM rats. After intraperitoneal injection of fluorescein sodium, the dynamic fundus photographs were taken. This figure shows the representative photos of each group during the intervention period. DM rats had different degrees of retinal vascular morphology changes from sixth week. PSP treatment alleviated the retinal vasculopathy in a dose-dependent manner. BC: blank control; DM: diabetes mellitus; PSP-H: Polygonatum sibiricum polysaccharide high; PSP-L: Polygonatum sibiricum polysaccharide low; PSP-M: Polygonatum sibiricum polysaccharide middle

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