Tetramethylpyrazine attenuates placental oxidative stress, inflammatory responses and endoplasmic reticulum stress in a mouse model of gestational diabetes mellitus

Protective effect of ligustrazine on oxidative stress and apoptosis following testicular torsion in rats

Testicular torsion is a common urologic emergency and one of the causes of infertility in males. It has been reported that ligustrazine may decrease oxidative stress and reduce ischemia-reperfusion injury. This study aims to investigate the protective effect of ligustrazine in ischemia-reperfusion injury after testicular torsion-detorsion. First, 40 rats were randomly and equally divided into TMP (Ligustrazine) group, the Testicular torsion (T/D) group, the Sham (Sham operation) group, and Control group. The left testis of rats in the TMP and T/D group was rotated for 2 h. The TMP group was intraperitoneally injected with ligustrazine solution and the T/D and the Sham groups were injected with normal saline. The left testes of four groups were obtained for assay on the 4th day after the operation. Average level of superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT) were higher in Sham and Control groups than T/D group and TMP group. Conversely, average level of malondialdehyde (MDA) and reactive oxygen species (ROS) was lower in Sham and Control groups than T/D group and TMP group. In contrast with the T/D group, SOD, GPX, and CAT enzymatic activities increased, whereas MDA and ROS content decreased in the TMP group (P < 0.05). Microscopic observation showed that the testicular tissue of the Sham and Control groups were basically normal. The TMP and T/D groups had significant testicular tissue damage, whereas the TMP group had less damage and apoptosis than the T/D group. The apoptotic index of germ cells in the TMP group (13.05 ± 4.41) was lower than the T/D group (30.23 ± 11.31) (P < 0.05) and higher (P < 0.05) than the Sham group (0.56 ± 0.29). So we found that Ligustrazine lowered ischemia-reperfusion injury after testicular torsion-detorsion by decreasing the reactive oxygen species and suppressing apoptosis.

Tetramethylpyrazine ameliorates systemic streptozotocin-induced Alzheimer-like pathology

Diabetes mellitus (DM) and its complications are the main threats to the global disease burden. DM-related cognitive dysfunction is a progressive neurodegenerative disease, similar to Alzheimer's disease (AD). The underlying pathophysiology remains unclear, and an effective treatment is unavailable. Tetramethylpyrazine (TMP) is a bioactive ingredient extracted from the plant Ligusticum wallichii, which has anti-diabetic and neuroprotective properties. In this study, streptozotocin (STZ) injection was used to establish a mouse STZ-AD model, and TMP was administered through the lateral ventricle (ICV) to evaluate the effects of TMP on cognitive ability and neurochemical changes and to explore the underlying cellular and molecular mechanisms. Using MWM and Y-maze behavioral paradigms, we observed that TMP protected against STZ-induced learning and memory impairment. STZ promoted the deposition of amyloid plaques, activation of glial cells, loss of neurons and synapses, and reduction of synaptic plasticity. In contrast, TMP restored these aberrations and improved cognitive deficits in STZ-induced diabetic animals. Moreover, TMP attenuated hippocampal mitochondrial dysfunction and oxidative stress through modulation of the SIRT1/Nrf2/ HO-1 pathway. This evidence shows that TMP exerts its therapeutic effects through multiple pathways. Our study provides new insights into the neuroprotective effects of TMP for the treatment of diabetes-related cognitive failure.

Kindlin-2 protects pancreatic β cells through inhibiting NLRP3 inflammasome activation in diabetic mice

Diabetes mellitus has been a major public health problem worldwide, characterized by insulin resistance and dysfunction of β-cells. A previous study showed that Kindlin-2 loss in β-cells dramatically reduces insulin secretion and decreases β-cell mass, resulting in severe diabetes-like phenotypes. It suggests that Kindlin-2 in β-cells play an important role in regulating glucose homeostasis. However, the effect of Kindlin-2 on the function of β-cells under chronic hyperglycemia in diabetes has not been explored. Here we report that Kindlin-2 overexpression ameliorates diabetes and improves insulin secretion in mice induced by streptozocin. In contrast, Kindlin-2 insufficiency exacerbates diabetes and promotes β-cells dysfunction and inflammation in β-cells induced by a high-fat diet (HFD). In vitro, Kindlin-2 overexpression prevented high-glucose (HG)-induced dysfunction in β-cells. Kindlin-2 overexpression also decreased the expression of pro-inflammatory cytokines and NLRP3 inflammasome expression in β-cells exposed to HG. Furthermore, the loss of Kindlin-2 aggravates the expression of inflammatory cytokines and NLRP3 induced by HG in β-cells. Collectively, we demonstrate that Kindlin-2 protects against diabetes by inhibiting NLRP3 inflammasome activation.

Ginsenoside Rh1 inhibits tumor growth in MDA-MB-231 breast cancer cells via mitochondrial ROS and ER stress-mediated signaling pathway

Ginsenoside-Rh1 (Rh1) is a ginseng-derived compound that has been reported to exert anticancer effects by regulating cell cycle arrest and apoptosis according to reactive oxygen species (ROS) production. However, the effects of Rh1 on mitochondrial dysfunction are involved in triple negative breast cancer (TNBC) cell apoptosis, and the related molecular mechanisms remain unknown. Rh1 treatment induced cell toxicity less than 50% at 50 μM. In addition, Rh1 induced apoptosis in TNBC cells through cleaved caspase-3 activation and G1/S arrest. The Rh1-treated TNBC cells showed a significant increase in mitochondrial ROS (mtROS), which in turn increased protein expression of mitochondrial molecules, such as Bak and cytochrome C, and caused the loss of mitochondrial membrane potential. Pretreatment with mitochondria-targeted antioxidant Mito-TEMPO alters the Rh1-reduced rate of mito- and glycol-ATP. Furthermore, Rh1 induces ER stress-mediated calcium accumulation via PERK/eIF2α/ATF4/CHOP pathway. Inhibition of ATF4 by siRNA transfection significantly inhibited Rh1-mediated apoptosis and calcium production. Interestingly, Mito-TEMPO treatment significantly reduced apoptosis and ER stress induced by Rh1. Finally, Rh1 at 5 mg/kg suppressed tumor growth through increased levels of ROS production, cleaved caspase-3, and ATF4 more than 5-fluorouracil treated group. Overall, our results suggest that Rh1 has potential for use in TNBC treatment.

Tetramethylpyrazine: A Review of Its Antitumor Potential and Mechanisms

Cancer remains a major public health threat. The mitigation of the associated morbidity and mortality remains a major research focus. From a molecular biological perspective, cancer is defined as uncontrolled cell division and abnormal cell growth caused by various gene mutations. Therefore, there remains an urgent need to develop safe and effective antitumor drugs. The antitumor effect of plant extracts, which are characterized by relatively low toxicity and adverse effect, has attracted significant attention. For example, increasing attention has been paid to the antitumor effects of tetramethylpyrazine (TMP), the active component of the Chinese medicine Chuanqiong, which can affect tumor cell proliferation, apoptosis, invasion, metastasis, and angiogenesis, as well as reverse chemotherapeutic resistance in neoplasms, thereby triggering antitumor effects. Moreover, TMP can be used in combination with chemotherapeutic agents to enhance their effects and reduce the side effect associated with chemotherapy. Herein, we review the antitumor effects of TMP to provide a theoretical basis and foundation for the further exploration of its underlying antitumor mechanisms and promoting its clinical application.

Tetramethylpyrazine alleviates endoplasmic reticulum stress‑activated apoptosis and related inflammation in chondrocytes

Excessive apoptosis of chondrocytes and degradation of the extracellular matrix (ECM) contribute to the typical pathological characteristics of osteoarthritis (OA). Various studies have reported that tetramethylpyrazine (TMP) protects against multiple disorders by inhibiting inflammation and oxidative stress. The present study investigated the effects of TMP on chondrocytes and evaluated the associated mechanisms. To determine the effect of TMP on OA and the underlying mechanisms, chondrocytes were incubated with TMP and IL-1β or thapsigargin (TG) Western blotting assays were performed to examine the expression levels of endoplasmic reticulum (ER) stress proteins, and TUNEL staining, fluorescence immunostaining and reverse transcription-quantitative PCR were used to determine the apoptosis levels, and catabolic and inflammatory factors. It was found that TMP protected chondrocytes by suppressing IL-1β-induced expression of glucose-regulated protein 78 (GRP78) and CHOP (an apoptotic protein). TMP regulated the TG-mediated upregulated expression of GRP78 and CHOP in the chondrocytes of rats, as well as markedly suppressed levels of ER stress-triggered inflammatory cytokines (TNF-α and IL-6). Furthermore, TMP modulated TG-induced changes in ECM catabolic metabolism in rat chondrocytes. Collectively, TMP alleviated ER-stress-activated apoptosis and related inflammation in chondrocytes, indicating that it has therapeutic potential for the treatment of OA.

Silencing cyclophilin A improves insulin secretion, reduces cell apoptosis, and alleviates inflammation as well as oxidant stress in high glucose-induced pancreatic β-cells via MAPK/NF-kb signaling pathway

Cyclophilin A is increased in the plasm of diabetic patients, while its effects on high glucose (HG)-stimulated pancreatic β-cells are still pending. The aim of this research is to investigate the effects of cyclophilin A inhibition on HG-challenged pancreatic β-cells. For investigating the effects of cyclophilin A decrease on HG-induced pancreatic β-cells, the cells were separated into normal glucose (NG), Mannitol, HG, HG + shRNA-NC, and HG + shRNA-Cyclophilin A-1 groups. The protein and mRNA expression were detected via Western blot and qRT-PCR. CCK-8 assay and flow cytometry were employed for assessing cell viability and apoptosis. The levels of oxidative stress, inflammation, and insulin secretion were detected by corresponding kits. The cyclophilin A was higher in HG group. Knockdown of cyclophilin A was able to increase insulin secretion, decrease cell apoptosis, and alleviate inflammation as well as oxidant stress in HG-treated pancreatic β-cells via MAPK/NF-kb pathway. Taken together, Cyclophilin A, highly expressed in pancreatic β-cells induced by HG, is a promising therapeutic target for diabetes. Knockdown of cyclophilin A has protective effects against HG-challenged pancreatic β-cells via regulation of MAPK/NF-kb pathway. The findings in this study provided a new strategy for diabetic treatment and paved the way for future researches on diabetes treatment.

Gestational diabetes mellitus, autistic traits and ADHD symptoms in toddlers: Placental inflammatory and oxidative stress cytokines do not play an intermediary role

OBJECTIVE

To evaluate whether gestational diabetes mellitus (GDM) is associated with increased risks of autistic traits and attention deficit/hyperactivity disorder (ADHD) among offspring and whether placental inflammatory and oxidative stress cytokines play an intermediary role.

METHODS

Based on a prospective cohort study from China, namely, the Ma'anshan Birth Cohort study (MABC), 3260 mother-child pairs were included. Autistic traits and ADHD symptoms among children were assessed at 18 months and 36 months, respectively. The mRNA expression levels of fourteen placental cytokines were determined using PCR. Logistic regression analysis was used to examine the associations between GDM and the risks of autistic traits or ADHD symptoms. Mediation analysis was used to assess the potential mediation effects of certain placental inflammatory factors.

RESULTS

Of the 3260 children, 419 (12.85%) were exposed to GDM. The prevalence rates of autistic traits and ADHD symptoms were 13.86% and 6.4%, respectively. A 48.6% increased risk of autistic traits was observed among offspring born to mothers with GDM [odds ratio (OR) = 1.49, 95% confidence interval (95%CI): 1.11-2.00)], while no significant association was found in terms of ADHD symptoms. There were significant positive associations between GDM and IL-10 expression and between HIF1-α and CRP mRNA expression and a significant negative association between GDM and CD206 mRNA expression. The expression of MCP-1 mRNA was negatively associated with the risk of autistic traits [adjusted OR = 0.73 (95%CI: 0.73-0.55)]. The levels of TNF-α were positively associated with the risk of ADHD symptoms [OR = 2.11 (95%CI: 1.39-3.21)], while GRP78 was inversely associated with it [OR = 0.64 (95%CI: 0.44-0.94)]. However, none of the 14 placental cytokines was involved as a key mediator.

CONCLUSION

Our findings suggest that GDM may act as a risk factor for autistic traits in offspring, while the biological mechanisms may not involve the 14 placental cytokines studied. No significant association between GDM and ADHD symptoms was observed.

Stromal Cell-Derived Factor (SDF) 2 and the Endoplasmic Reticulum Stress Response of Trophoblast Cells in Gestational Diabetes Mellitus and In vitro Hyperglycaemic Condition

BACKGROUND AND AIM

The endoplasmic reticulum (ER) stress response and the unfolded protein response (UPR) are essential cellular mechanisms to ensure the proper functioning of ER in adverse conditions. However, activation of these pathways has also been associated with insulin resistance and cell death in pathological conditions such as diabetes mellitus. In the present study, we investigated whether stromal cell-derived factor 2 (SDF2)-an ER stress-responsive factor-is related to ER response in placental cells exposed to maternal gestational diabetes mellitus (GDM) or to a hyperglycaemic in vitro condition.

OBJECTIVE

The study aimed to investigate the role of SDF2 in BeWo cells , a trophoblast cell line originating from choriocarcinoma , and in placental tissue under hyperglycaemic conditions.

METHODS

Protein levels of SDF2 and UPR factors, glucose-related protein 78 (GRP78) and eukaryotic initiation factor 2 alpha (elF2 alpha) were evaluated in the placentae of pregnant women diagnosed with GDM and treated by diet-control (insulin was added when necessary). The mRNA expression of SDF2 and UPR factors CHOP and sXBP1 were assessed in cultured BeWo cells challenged with glucose and treated with or without insulin.

RESULTS

SDF2 expression was increased in the placentae of GDM women treated with diet. However, its values were similar to those of normoglycemic controls when the GDM women were treated with insulin and diet. BeWo cells cultured with high glucose and insulin showed decreased SDF2 expression, while high glucose increased CHOP and sXBP1 expression, which was then significantly reverted with insulin treatment.

CONCLUSION

Our findings extend the understanding of ER stress and SDF2 expression in placentae exposed to hyperglycaemia, highlighting the relevance of insulin in reducing the levels of ER stress factors in placental cells. Understanding the effect of ER stress partners such as SDF2 on signalling pathways involved in gestation, complicated by hyperglycaemia, is pivotal for basic biomedical research and may lead to new therapeutic possibilities.

2,3,5,6-Tetramethylpyrazine protects retinal photoreceptors against endoplasmic reticulum stress by modulating ATF4-mediated inhibition of PRP aggregation

Endoplasmic reticulum (ER) stress is a common threat to photoreceptors during the pathogenesis of chronic retinopathies and often results in irreversible visual impairment. 2,3,5,6-Tetramethylpyrazine (TMP), which possesses many beneficial pharmacological activities, is a potential drug that could be used to protect photoreceptors. In the present study, we found that the cellular growth rate of 661 W cells cultured under low glucose conditions was lower than that of control cells, while the G2/M phase of the cell cycle was longer. We further found that the mitochondrial membrane potential (ΔΨm) was lower and that ER stress factor expression was increased in 661 W cells cultured under low glucose conditions. TMP reversed these trends. Visual function and cell counts in the outer nuclear layer (ONL) were low and the TUNEL-positive rate in the ONL was high in a C3H mouse model of spontaneous retinal degeneration. Similarly, visual function was decreased, and the TUNEL-positive rate in the ONL was increased in fasted C57/BL6j mice compared with control mice. On the other hand, ER stress factor expression was found to be increased in the retinas of both mouse models, as shown by reverse transcription real-time PCR (RT-qPCR) and western blotting. TMP reversed the physiological and molecular biological variations observed in both mouse models, and ATF4 expression was enhanced again. Further investigation by using western blotting illustrated that the proportion of insoluble prion protein (PRP) versus soluble PRP was reduced both in vitro and in vivo. Taken together, these results suggest that TMP increased the functions of photoreceptors by alleviating ER stress in vitro and in vivo, and the intrinsic mechanism was the ATF4-mediated inhibition of PRP aggregation. TMP may potentially be used clinically as a therapeutic agent to attenuate the functional loss of photoreceptors during the pathogenesis of chronic retinopathies. KEY MESSAGES: • Already known: TMP is a beneficial drug mainly used in clinic to enhance organ functions, and the intrinsic mechanism is still worthy of exploring. • New in the study: We discovered that TMP ameliorated retinal photoreceptors function via ER stress alleviation, which was promoted by ATF4-mediated inhibition of PRP aggregation. • Application prospect: In prospective clinical practices, TMP may potentially be used in the clinic as a therapeutic agent to attenuate the photoreceptors functional reduction in chronic retinopathies.

2,3,5,6-Tetramethylpyrazine improves diet-induced whole-body insulin resistance via suppressing white adipose tissue lipolysis in mice

Ectopic lipid accumulation in skeletal muscle and liver arises when nutrient storage systems are exposed to chronic energy surplus, leading to whole-body insulin resistance and metabolic disorders. One recent study has shown 2,3,5,6-tetramethylpyrazine (TMP), highly enriched in roasted foodstuffs, such as cocoa and peanuts, significantly decreases blood lipids levels and ameliorates ApoE-defect induced atherosclerosis suggesting a potent role of TMP in lipid dysregulation improvement. Here, we evaluated the impact of TMP treatment on high fat diet (HFD)-induced insulin resistance. Using hyperinsulinemic-euglycemic mouse clamp, we demonstrated 4-week TMP treatment improved whole-body insulin resistance in HFD-fed mice through suppressing lipolysis in white adipose tissue associated with reduced triglyceride in liver and improved glucose uptake in skeletal muscle. Collectively, our work provides proof-of-concept data to support the development of white adipose tissue-targeted medicine for the treatment of metabolic disorder.