| Objective This study aims to investigate the changes of serum 25(OH)D levels in diabetic microvascular complications and to analysis the relationship between serum 25(OH)D and diabetic microvascular complications, thus providing basis for early prevention and treatment of diabetic microvascular complications (diabetic peripheral neuropathy, diabetic retinopathy and diabetic nephropathy).Methods We recruited 300 patients with type 2 diabetes mellitus who had been hospitalized in the Departments of Endocrinology and Metabolism of First Affiliated Hospital of Shihezi University School of Medicine during January 2013 and August 2013. Controls were recruited from healthy individuals who completed health examinations in the hospital.Written informed consent was obtained from all patients before they entered the study. Clinical data were collected from all participants. Fasting blood samples were collected for estimation of vitamin D and other routine biochemical parameters, including Cr, Ca, P, HbA1c, TC, TG, LDL-c, and HDL-c. In addition, each patient provided first morning urine samples for determination of urine microalbumin/creatinine ratio (UACR). Fundus examination was performed for the patients using nonmydriatic fundus camera. Diabetic neuropathy were evaluated using neuropathy symptom score (NSS), neuropathy disability score (NDS) and neural electrophysiological test. Then we assessed the relationship between 25(OH)D levels and microvascular complications in patients with type 2 diabetes mellitus.Results 1.Serum 25(OH)D was lower in T2DM group [50.10±29.90nmol/L] compared with control group [69.25±31.20nmol/L] (P<0.05).59.2% of controls and 74.7% in diabetics had 25(OH)D deficiency, and the differences were statistically significant (P<0.05). There was no significant difference in age, gender, TG, HDL-c, Cr, Ca and P between the T2DM and control groups (P>0.05). However, the T2DM subjects had higher BMI, SBP, DBP, TC and LDL-c than control subjects (P< 0.05).2. According to serum 25(OH)D level, the T2DM subjects were divided into 25(OH)D deficient group and 25(OH)D normal group. The data showed that there was no significant difference in age, duration, SBP, DBP, FBS, TC, TG, HDL-c, LDL-c, Cr, Ca and P between the two groups (P>0.05). The T2DM subjects in 25(OH)D deficient group had higher BMI and HbAlc than those in 25(OH)D normal group (P<0.05). The incidence of diabetic subjects with DPN, DR, and DN in 25(OH)D deficient group was higher than in 25(OH)D normal group(P<0.05).3. Serum 25(OH)D was lower in DPN group [40.75±23.75nmol/L] compared with NDPN group[54.50±24.50nmol/L] (P<0.05). Serum 25(OH)D was lower in DR group [41.55±26.00nmol/L]compared with NDR group[54.75±26.25nmol/L] (P<0.05). Serum 25(OH)D was lower in DN group [42.35±26.83nmol/L]compared with NDN group[53.90±22.14nmol/L] (P<0.05).4. Analysis of the impacting factors of diabetic peripheral neuropathy:With or without DPN as the dependent variable, single factor analysis showed that 25(OH)D, diabetic duration, HbA1c, SBP, TC, and LDL-c were associated with DPN (P<0.05). Logistic regression analysis showed that 25(OH)D was negative correlation with diabetic peripheral neuropathy, which was protective factor; diabetes duration and HbA1c were positive correlation with diabetic peripheral neuropathy, which were risk factors.5. Analysis of the impacting factors of diabetic retinopathy:With or without DR as the dependent variable, single factor analysis showed that 25(OH)D, age, diabetic duration, BMI and HbAlc were associated with DR (P<0.05).Logistic regression analysis showed that 25(OH)D was negative correlation with diabetic retinopathy, which was protective factor; age was positive correlation with diabetic retinopathy, which was risk factor.6. Analysis of the impacting factors of diabetic nephropathy:With or without DN as the dependent variable, single factor analysis showed that 25(OH)D, age, diabetic duration, HbA1c, SBP and LDL-c were associated with DN (P0.05).Logistic regression analysis showed that 25(OH)D was negative correlation with diabetic nephropathy, which was protective factor; diabetic duration and SBP were positive correlation with diabetic retinopathy, which were risk factors.Conclusion serum 25(OH)D is decreased in patients with type 2 diabetes mellitus and diabetic microvascular complications. Decreased serum 25 (OH) D level is closely associated with diabetic microvascular complications, such as diabetic peripheral neuropathy, diabetic retinopathy and diabetic nephropathy. Serum 25(OH)D is a protective factor of diabetic microvascular complications, and further studies are required to confirm if vitamin D supplementation could prevent or delay the onset.Objective Neurotrophic factors deficiency and oxidative stress play an important role in diabetic peripheral neuropathy. It's suggesting that the active Vitamin D3 [1,25(OH)2D3] has neurotrophic and neuroprotective effects. The previous part of our research showed that vitamin D deficiency was associated with diabetic peripheral neuropathy. However, it's unknown that whether 1,25(OH)2D3 could affect on diabetic peripheral neuropathy. Therefore, we will establish diabetic rats model with 1,25(OH)2D3 intervention, and explore that 1,25(OH)2D3 could have protective effect on diabetic peripheral neuropathy and underlying mechanism.Methods Thirty male SD rats were randomly equally divided into two groups:control group (CT group) and diabetic model group. Diabetic rats were induced by intraperitoneal injection of streptozocin (STZ,60mg/kg) and confirmed by a blood glucose?16.7mmol/L. Then the diabetic model rats were divided into two groups:diabetes group (DM group) and diabetes treated with 1,25(OH)2D3 group (DM+VD3 group). CT group and DM group rats received saline by oral gavage, and DM+VD3 group rats received 1,25(OH)2D3 once a day for twelve weeks. Fasting plasma glucose was measured weekly, and the motor conduction of sciatic nerve was detected every four weeks. Rats were anesthetized and killed in twelfth weeks, and the sciatic nerves were isolated. Then we observed the pathological changes of sciatic nerve in each group, and detected the expression levels of NGF, NT-3, NADPH oxidase subunit P22phox and NF-?B p65 using immunohistochemistry and Western Blot, respectively.Results 1. Fasting plasma glucose:Compared with the same period of control group rats, the fasting plasma glucose values of DM and DM+VD3 groups rats were significantly increased before treatment and after 4,8,12 weeks treatment (P<0.01). Compared with the same period of the DM group rats, fasting plasma glucose values of DM+VD3 groups were decreased after 12 weeks treatment (P<0.05), but there was no significant difference (P>0.05) after 4,8 weeks treatment. Compared with those before treatment, fasting plasma glucose values of DM+VD3 group rats were decreased after 12 weeks treatment (P<0.05).2. Sciatic nerve motor conduction velocity:Compared with the same period of control group rats, sciatic nerve motor conduction velocity of DM and DM+VD3 groups rats were significantly decreased (P<0.01). Compared with the same period of DM group rats, sciatic nerve motor conduction velocity of DM+VD3 groups rats were increased after 8 weeks treatment, however, there was no statistical significance (P>0.05). After 12 weeks 1,25(OH)2D3 treatment, sciatic nerve motor conduction velocity of DM+VD3 groups rats were higher than those of DM group in the same period (P<0.05).3. HE staining results showed that it was hard-packed, in alignment and homogeneous distribution in the sciatic nerve fibers of CT group; and there were larger gap, loosely arranged and fracture and degeneration in multiple places of DM group; Nerve fiber structure in DM+VD3 group were more closely,more regularly arranged and reducing fracture and degeneration of sciatic nerve.4.Immunohistochemistry showed that NGF expression was strongly positive in sciatic nerve Schwann cells in CT group rats, but very week in DM group; compared with DM group, NGF positive expression was increased in DM+VD3 group. The Integrated option density (IOD) values of DM group were obviously lower than that of CT group (P<0.05); compared with DM group, the IOD values of DM+VD3 group were higher (P<0.05). Western Blot results showed that:compared with CT group, NGF expression was reduced in sciatic nerve tissue of DM group rats (P<0.05); compared with DM group, NGF expression was increased in DM+VD3 group (P<0.05).5. Immunohistochemistry showed that NT-3 expression was strongly positive in sciatic nerve Schwann cells in CT group rats, but very week in DM group; compared with DM group, NT-3 positive expression was increased in DM+VD3 group. The IOD values of DM group were obviously lower than those of CT group (P<0.05); compared with DM group, the IOD values of DM+VD3 group was higher (P<0.05). Western Blot results showed that:compared with CT group, NT-3 expression was reduced in sciatic nerve tissue of DM group rats (P<0.05); compared with DM group, NT-3 expression was increased in DM+VD3 group (P<0.05).6. Immunohistochemistry showed that NADPH oxidase subunit P22phox expression was strongly positive in sciatic nerve Schwann cells in DM group rats, but very week in CT group; compared with DM group, NADPH oxidase subunit P22phox positive expression was decreased in DM+VD3 group. The IOD values of DM group were obviously higher than those of CT group (P<0.05); compared with DM group, the IOD values of DM+VD3 group were lower (P<0.05).Western Blot results showed that:compared with CT group, NADPH oxidase subunit P22phox expression was increased in sciatic nerve tissue of DM group rats (P<0.05); compared with DM group, NADPH oxidase subunit P22phox expression was reduced in DM+VD3 group (P<0.05).7. Immunohistochemistry showed that NF-?B p65 expression was strongly positive in sciatic nerve Schwann cells in DM group rats, but very week in CT group; compared with DM group, NF-?B p65 positive expression was decreased in DM+VD3 group. The IOD values of DM group were obviously higher than those of CT group (P<0.05);compared with DM group, the IOD values of DM+VD3 group were lower (P<0.05).Western Blot results showed that:compared with CT group, NF-?B p65 expression was increased in sciatic nerve tissue of DM group rats (P<0.05);compared with DM group, NF-?B p65 expression was reduced in DM+VD3 group (P<0.05).Conclusion 1,25(OH)2D3 could caused a decreased blood glucose, and improve sciatic nerve motor conduction velocity of diabetic peripheral neuropathy rats, which might have a protective effect on sciatic nerve morphology.1,25(OH)2D3 could rise NGF and NT-3 expression in sciatic nerve of diabetic peripheral neuropathy rats, these may be one of the effective targets of 1,25(OH)2D3 prevention and treatment diabetic peripheral neuropathy. Moreover,1,25(OH)2D3 could suppress NADPH oxidase subunit P22phox expression in sciatic nerve of diabetic peripheral neuropathy rats, and antagonize oxidative stress, reducing NF-?B p65 expression, which may exert protective effect on diabetic peripheral neuropathy. |
PDF Full Text Request