Purpose: To investigate the effect of astragaloside IV (AS-IV) on mitochondrial-dependent apoptosis in the dorsal root ganglion of diabetic peripheral neuropathy (DPN) rats through the SIRT1/p53 pathway. Methods: Diabetic rat model was induced by high-carbohydrate/high-fat diet and intraperitoneal injection of STZ. Diabetic rats were divided into three groups (n =16 per group): DPN group, AS-IV group (60mg/kg/d) and α-lipoic acid (ALA) group (60mg/kg/d). Weight and blood glucose levels were monitored every 4 weeks for 12 weeks. DPN was evaluated using the Von Frey Filaments Test and nerve conduction velocity. The dorsal root ganglia of rats were isolated and the pathological changes of mitochondria were observed by electron microscopy. The activity of mitochondrial electron transport chain complex, mitochondrial membrane potential, malonaldehyde (MDA) and glutathione (GSH) levels were measured. Neural apoptosis was detected using the Terminal Deoxynucleotidyl Nick-End Labeling (TUNEL) assay kit. The cleaved caspase-3, major proteins in the SIRT1/p53 pathway, including SIRT1, acetyl p53, Drp1, BAX, and BCL-2, were detected using immunohistochemistry and Western blot. Gene expression of major proteins in the SIRT1/p53 pathway was also detected. Results: After 12 weeks of treatment, AS-IV and ALA did not significantly affect body weight or fasting glucose levels, but reduced mechanical abnormal pain in DPN and improved nerve conduction velocity. AS-IV and ALA increased the level of GSH and decreased the level of MDA. Both AS-IV and ALA can reduce mitochondrial damage, improve mitochondrial electron transport chain complex activity and mitochondrial membrane potential, and reduce the percentages of positive cells with DNA fragmentation and the expression of cleaved caspase-3 protein. AS-IV and ALA up-regulated the expression of SIRT1 and down-regulated the expression of acetyl-p53, Drp1 and the ratio of BAX to BCL-2. Changes in gene expression were similar. Conclusion: AS-IV can reduce the occurrence of mitochondrial-dependent apoptosis by regulating the SIRT1/p53 pathway. It has a similar therapeutic effect as ALA and is therefore a promising drug for the potential treatment of DPN.

Introduction. Cardiovascular disease constitutes the leading cause of mortality in patients with chronic kidney disease (CKD), which is termed cardiorenal syndrome type 4 (CRS-4). Here, we report the development of pathological cardiac remodeling and fibrosis in unilateral urinary obstruction (UUO) rats. Methods. Hematoxylin and eosin (HE) staining was performed to observe the pathology of myocardial tissue. The degree of myocardial tissue fibrosis was observed by Masson and Sirius red staining. Immunohistochemical staining was applied to detect the expression of CD34 and CD105 in myocardial tissue, and immunofluorescent staining was performed to examine the expression of CD34, collagen I/collagen III, and alpha smooth muscle actin (α-SMA). The expression of the signal pathway-related proteins vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor receptor 2 (VEGFR2), nuclear factor κB (NF-κB), and interleukin (IL)-1β was tested by western blotting. Reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the mRNA levels of serum and glucocorticoid-inducible kinase (SGK)-1, NF-κB, and interleukin-1β (IL-1β). Results. The results showed the development of pathological cardiac remodeling and cardiac dysfunction in UUO rats. Moreover, there was more angiogenesis and endothelial-mesenchymal transition (End-MT) in the UUO group, and these effects were inhibited by eplerenone. Conclusions. The results indicated that this cardiac fibrosis was associated with angiogenesis and that End-MT was related to aldosterone and mineralocorticoid receptor (MR) activation. Moreover, in association with the MR/IL-1β/VEGFA signaling pathway, early treatment with the MR antagonist eplerenone in rats with UUO-induced CKD may significantly attenuate MR activation and cardiac fibrosis.

Purpose: To explore the mechanism by which alpha-lipoic acid (ALA) regulates mitochondrial axonal transport to protect the sciatic nerve in diabetic rats. Methods: Among 55 healthy male Sprague‒Dawley rats, 40 were randomly selected, fed a high-carbohydrate/high-fat diet and intraperitoneally injected with streptozotocin (STZ) to induce diabetes. Diabetic rats were randomly divided into diabetic peripheral neuropathy (DPN) and alpha lipoic acid (ALA) groups, with 15 rats in each group, excluding the rats in which diabetes failed to be induced and the dead rats. The other 15 rats were used as the control group. The rats in the ALA group were administered an ALA suspension (60 mg/kg/day) by gavage for 12 weeks. The rats in the control group and DPN group were gavaged with an equal volume of distilled water every day for 12 weeks. After the intervention was complete, the motor nerve conduction velocity (MNCV) and paw withdrawal threshold (PWT) were measured. Morphological changes in the sciatic nerve were observed by HE staining. Immunofluorescence staining and Western blotting were performed to measure protein expression levels. In vitro, a model of NSC34 cell injury was established by treating cells with high concentrations of glucose and palmitic acid sodium. NSC34 cells were randomly divided into the control group, DPN group and ALA group. The ALA group was treated with ALA for 24 hours. Changes in the axons of NSC34 cells were assessed by measuring the length of the axons. Immunofluorescence staining was performed to determine the fluorescence intensity of the cells, and Western blotting was performed to determine the grayscale value of each band. Results: ALA increased the MNCV and PWT in DPN rats and increased the levels of phosphorylated AMP-activated protein kinase (p-AMPK) and phosphorylated cAMP-response element-binding protein (p-CREB). The expression of a motor protein involved in anterograde axonal mitochondrial transport, kinesin family member 5A (KIF5A), was upregulated, whereas the expression of a dynein protein involved in mitochondrial retrograde transport, Dynein cytoplasmic 1 intermediate chain 2 (DYNC1I2), was downregulated by ALA. Conclusion: The results of this study suggest that ALA alleviates peripheral nerve injury in diabetic rats by promoting the anterograde axonal transport of mitochondria, which may be related to AMPK/CREB signaling.

Purpose To investigate the AMPK/CREB pathway–mediated effect of alpha-lipoic acid (ALA) on the sciatic nerve of rats with diabetic peripheral neuropathy (DPN) and to attempt to elucidate the underlying mechanism. Methods In vivo experiment, healthy male Sprague-Dawley (SD) rats were induced by high-carbohydrate/high-fat diet and intraperitoneal injection of streptozotocin (STZ) (30 mg·kg^− 1) to induce diabetes. The diabetes SD rats were randomly divided into DPN group and alpha lipoic acid (ALA) group (n = 15). The other 15 SD rats were set as Control group. Then Control group and DPN group received the same amount of normal saline by intragastric administration, and ALA groups received ALA intervention every day for 12 weeks. Motor nerve conduction velocity (MNCV) and Paw Withdrawal Threshold (PWT) were detected. The morphological changes were observed by HE staining in sciatic nerves. Kinesin family member 5A (KIF5A), Dynein Cytoplasmic 1 Intermediate Chain 2 (DYNC1I2), phosphorylated Adenosine 5'-monophosphate (AMP) activated protein kinase (p-AMPK), Adenosine 5'-monophosphate (AMP) activated protein kinase (AMPK), phosphorylated cAMP responsive element binding protein(p-CREB) and cAMP responsive element binding protein(CREB)were observed by immunofluorescence assay and Western blot. In the vitro cell experiment, the NSC34 cells injury model was established by treating with 50 mmol·L^− 1 of high glucose and 250 µmol·L^− 1 of palmitic acid sodium. NSC34 cells were randomly divided into Control group, Model group and alpha lipoic acid intervention group (ALA group). ALA group was given corresponding ALA for 24 hours of intervention. The axon changes were observed by measured neuron axon length in NSC34 cells. KIF5A, DYNC1I2, p-AMPK,AMPK, p-CREB and CREB were observed by immunofluorescence assay and Western blot. Results ALA improved the MNCV and PTW of rats with DPN and reduced their mechanical pain threshold. AMPK was activated by ALA. p-CREB, KIF5A expression was upregulated, while DYNC1I2 expression was downregulated. ALA regulates mitochondrial transport in peripheral nerve. Conclusion ALA activates CREB and KIF5A through AMPK, regulates positive mitochondrial transport, protects axons, and attenuates DPN.