Complications in the spine associated with type 2 diabetes: The role of advanced glycation end-products

Protective effects of GuanXinNing tablet (GXNT) on diabetic encephalopathy in zucker diabetic obesity (ZDF) rats

BACKGROUND

Diabetic encephalopathy (DE) is a complication of diabetes that leads to cognitive and behavioral decline. Utilizing safe and effective complementary and alternative medications for its management is a wise choice. Previous studies have shown that GuanXinNing Tablet (GXNT), an oral preparation primarily derived from two Chinese herbs, Salvia miltiorrhiza Bge. and Ligusticum chuanxiong Hort., exerts a beneficial neuroprotective effect. In this study, we explored the protective effects of GXNT on DE in male Zucker diabetic fatty (ZDF) rats induced by a high-fat diet, aiming to ascertain its significance and potential mechanisms.

METHODS

ZDF rats were induced to develop type 2 diabetes (T2DM) with DE by a high-fat diet and treated with GXNT for 8 weeks until they were 20 weeks old. Throughout the experiment, the animals' vital parameters, such as body weight, were continuously monitored. Cognitive function was evaluated using the Y maze test. Biochemical kits were employed to analyze blood glucose, lipids, and vascular endothelial-related factors. Cerebrovascular lesions were assessed using magnetic resonance angiography (MRA) imaging. Brain lesions were evaluated using hematoxylin and eosin (H&E) staining and ultrastructure observation. IgG and albumin (ALB) leakage were detected using immunofluorescence.

RESULTS

GXNT demonstrated an enhancement in the overall well-being of the animals. It notably improved cognitive and behavioral abilities, as demonstrated by extended retention time in the novel heterogeneous arm during the Y-maze test. GXNT effectively regulated glucose and lipid metabolism, reducing fasting and postprandial blood glucose, glycated hemoglobin (HbA1c), and total cholesterol (TC) levels. Additionally, it exhibited a protective effect on the vascular endothelium by reducing the serum TXB2/PGI2 ratio while elevating NO and PGI2 levels. Moreover, GXNT ameliorated stenosis and occlusion in cerebral vessel branches, increased the number of microvessels and neurons around the hippocampus, and improved microvascular occlusion in the cerebral cortex, along with addressing perivascular cell abnormalities. Immunofluorescence staining showed a decrease in the fluorescence intensity of IgG and ALB in the cerebral cortex.

CONCLUSIONS

GXNT demonstrated a highly satisfactory protective effect on DE in ZDF rats. Its mechanism of action could be based on the regulation of glucolipid metabolism and its protective effect on the vascular endothelium.

Effects of continuous subcutaneous insulin infusion on the microstructures, mechanical properties and bone mineral compositions of lumbar spines in type 2 diabetic rats

Background

Continuous subcutaneous insulin infusion (CSII) for the treatment of type 2 diabetes (T2D) can improve the structure and strength of femur of rats, but the effect of CSII treatment on the lumbar spine of T2D rats is unknown. The purpose of this study is to investigate the effects of CSII on the microstructure, multi-scale mechanical properties and bone mineral composition of the lumbar spine in T2D rats.

Methods

Seventy 6-week-old male Sprague–Dawley (SD) rats were divided into two batches, each including Control, T2D, CSII and Placebo groups, and the duration of insulin treatment was 4-week and 8-week, respectively. At the end of the experiment, the rats were sacrificed to take their lumbar spine. Microstructure, bone mineral composition and nanoscopic-mesoscopic-apparentand-macroscopic mechanical properties were evaluated through micro-computed tomography (micro-CT), Raman spectroscopy, nanoindentation test, nonlinear finite element analysis and compression test.

Results

It was found that 4 weeks later, T2D significantly decreased trabecular thickness (Tb.Th), nanoscopic-apparent and partial mesoscopic mechanical parameters of lumbar spine (P < 0.05), and significantly increased bone mineral composition parameters of cortical bone (P < 0.05). It was shown that CSII significantly improved nanoscopic-apparent mechanical parameters (P < 0.05). In addition, 8 weeks later, T2D significantly decreased bone mineral density (BMD), bone volume fraction (BV/TV) and macroscopic mechanical parameters (P < 0.05), and significantly increased bone mineral composition parameters of cancellous bone (P < 0.05). CSII treatment significantly improved partial mesoscopic-macroscopic mechanical parameters and some cortical bone mineral composition parameters (P < 0.05).

Conclusions

CSII treatment can significantly improve the nanoscopic-mesoscopic-apparent-macroscopic mechanical properties of the lumbar spine in T2D rats, as well as the bone structure and bone mineral composition of the lumbar vertebrae, but it will take longer treatment time to restore the normal level. In addition, T2D and CSII treatment affected bone mineral composition of cortical bone earlier than cancellous bone of lumbar spine in rat. Our study can provide evidence for clinical prevention and treatment of T2D-related bone diseases.

Omeprazole inhibits α-glucosidase activity and the formation of nonenzymatic glycation products: Activity and mechanism

In this study, the inhibitory effect and mechanism of omeprazole on α-glucosidase and nonenzymatic glycation were investigated in vitro by using multi-spectroscopic methods and molecular docking. Enzyme kinetic results showed that omeprazole inhibited α-glucosidase in a reversible and noncompetitive manner (IC₅₀= 0.595 ± 0.003 mM). The results from fluorescence quenching and thermomechanical analyses signified that omeprazole reduced the fluorescence intensity of α-glucosidase by forming an omeprazole-α-glucosidase complex primarily driven by hydrogen bonds. Molecular docking further confirmed that hydrogen bonds and hydrophobic forces were the major driving forces for omeprazole binding to α-glucosidase. The nonenzymatic glycation assays revealed that omeprazole had a moderate inhibition against the formation of fructosamine, dicarbonyl compounds, and advanced glycation end products (AGEs). This study provides a new inhibitor of both α-glucosidase and nonenzymatic glycation and provides a practicable candidate for treating diabetes and its complications.

Methods: A new protocol for in vitro red blood cell glycation

During diabetes, the characteristic hyperglycemia can induce red blood cell glycation. Several researchers have proposed different protocols to perform an in vitro model to study this phenomenon. In this article, some of the most important in vitro glycation protocols available in the bibliography were compared to each other. The incubation parameters as the suspension medium, glucose concentration, red blood cell concentration, time, and temperature were analyzed. Also, several assays were carried out in our laboratory, and glycated hemoglobin, erythrocyte aggregation and viscoelasticity were determined for the protocol validation. Based on the bibliographic analysis and our experimental results, an optimal protocol for in vitro glycation of red blood cells is presented.