Ginkgo biloba extract EGB761 protects against aging-associated diastolic dysfunction in cardiomyocytes of D-galactose-induced aging rat

Cardiovascular Activity of Ginkgo biloba-An Insight from Healthy Subjects

Ginkgo biloba is the oldest living tree species in the world. Despite less than encouraging clinical results, extracts from its leaves are among the most used herbal preparations in the prevention and treatment of cardiovascular diseases. Most data on the efficacy of Ginkgo biloba on cardiovascular disease is from clinical studies, with few results from healthy subjects. This paper aims to provide a comprehensive review of the mechanisms underlying the known beneficial cardiovascular activities of Ginkgo biloba. It displays myocardial suppressant and vasorelaxant activities ex vivo, potentiating endothelial-dependent and -independent pathways. It improves perfusion in different vascular beds, namely ocular, cochlear, cutaneous, cerebral, and coronary. Although scarce, evidence suggests that Ginkgo biloba displays a heterogeneous effect on tissue perfusion which is dependent on the individual elimination pathways. It displays an acceptable safety profile, with most reported adverse reactions constituting rare occurrences. Collectively, Ginkgo biloba positively impacts cardiovascular physiology, improving hemodynamics and organ perfusion. In the future, better controlled clinical studies should be performed in order to identify the target populations who may benefit the most from pharmacotherapeutic interventions involving Ginkgo biloba.

ER stress in cardiac aging, a current view on the D-galactose model

Longitudinal studies are mandatory to study aging, however, they have certain drawbacks, for example, they require strict maintenance that is expensive given the breeding time (approximately 2 years) and with a low survival rate, having some animals to study very limitedly. In vitro studies provide useful and invaluable information on the cellular and molecular mechanisms that help understand the aging process to overcome these aspects. In particular, the model of premature aging induced by chronic exposure to D-galactose (D-Gal) offers a very similar picture to that which occurs in natural aging. This model mimics most of the old animals' cellular processes, such as oxidative stress, mitochondrial dysfunction, increased advanced glycation end products (AGEs), inflammation, and senescence-associated secretory phenotype (SASP). However, the information related to the endoplasmic reticulum (ER) stress and, subsequently, the unfolded protein response (UPR) is not fully elucidated. Therefore, this review brings together the most current information on this response in the D-Gal-induced aging model and its effect on cardiac structure and function.

Deubiquitinating enzyme USP30 negatively regulates mitophagy and accelerates myocardial cell senescence through antagonism of Parkin

Cell senescence is associated with age-related pathological changes. Increasing evidence has revealed that mitophagy can selectively remove dysfunctional mitochondria. Overexpression of ubiquitin-specific protease 30 (USP30) has been documented to influence mitophagy and deubiquitination of mitochondrial Parkin substrates. This study was conducted to evaluate the roles of USP30 and Parkin in myocardial cell senescence and mitophagy. Initially, myocardial cells were isolated from neonatal SD rats and subjected to d-gal treatment to induce cell senescence, after which the effects of d-gal on mitochondria damage, ROS production, cell senescence, and mitophagy were assessed. The myocardial cells were infected with lentiviruses bearing overexpression plasmids or shRNA targeting Parkin or USP30 to elucidate the effects of Parkin and USP30 on d-gal-induced mitophagy damage and cell senescence. Finally, aging was induced in rats by subcutaneous injection of d-gal to determine the role of Parkin and USP30 on cell senescence in vivo. d-gal was found to trigger mitochondria damage, ROS production, and cell senescence in myocardial cells. The overexpression of Parkin or silencing of USP30 reduced d-gal-induced mitochondrial damage and relieved d-gal-induced myocardial cell senescence. Moreover, the in vivo experiments validated that either elevation of Parkin or silencing USP30 could alleviate d-gal-induced myocardial cell senescence in rats. Silencing USP30 alleviates d-gal-induced mitochondrial damage and consequently suppresses myocardial cell senescence by activating Parkin. Our study highlights the potential of USP30 as a novel target against myocardial cell senescence.

The characterisation of the in vitro metabolism and transport of 6-hydroxykynurenic acid, an important constituent of Ginkgo biloba extracts

6-Hydroxykynurenic acid (6-HKA) is a nitrogen-containing phenolic acid compound in Ginkgo biloba leaves. The pharmacological activities of 6-HKA have been reported and shown that 6-HKA has the potential to become a therapeutic drug and may play an important role in the treatment of nervous system diseases. However, there are few studies on the drug metabolism and transport of 6-HKA. The aim of this study is to investigate the in vitro metabolism of 6-HKA and its interaction with multiple important drug transporters.The in vitro metabolism experiments in the present study demonstrate that 6-HKA might not undergo phase-I or phase-II metabolism in hepatic microsomes/S9 of rats. In addition, some drug transporters, including OAT1/3, OCT2, MDR1, OATP1B1, MATE1/2K and OCTN2, were investigated. The cellular uptake assays indicate that 6-HKA exhibits inhibition to the transport of classical substrates mediated by OAT3, OCT2, MATE2K and OCTN2 but has no significant effect on the transport of substrates mediated by MDR1, OAT1, OATP1B1 or MATE1. Further investigation of cellular accumulation assays shows that 6-HKA might be the substrate of OAT3, but not OCT2 or OCTN2. The bidirectional transport study suggests that 6-HKA is not a substrate of MDR1.The information about the in vitro metabolism of 6-HKA and the interaction between 6-HKA and some transporters will help us to better understand the pharmacokinetic properties of 6-HKA and provide reference for its pharmacodynamics, DDIs and drug-food interactions studies.

New Insight into the Mechanisms of Ginkgo Biloba Extract in Vascular Aging Prevention

BACKGROUND

Aging-associated vascular dysfunction promotes cardiovascular diseases. Recently, Ginkgo biloba extract (GBE) has attracted considerable attention in the prevention of aged vasculature.

METHODS

This review discusses the pathophysiological alterations in aged vasculature and the underlying mechanisms of GBE in vascular aging suppression.

RESULTS

Both arterial stiffening and endothelial dysfunction are critical aging-related vascular phenotypes that result in the progression of cardiovascular diseases in the general population. Consistent oxidative stress and inflammatory reaction lead to vascular dysfunction. GBE ameliorates aging-related vascular dysfunction, due to its antioxidant and anti-inflammatory properties. The main effects of GBE in aged vasculature might be associated with the longevity signaling pathways. GBE also attenuates the progression of vascular aging in diabetes mellitus via regulation of glucose and lipid metabolism.

CONCLUSION

GBE plays an important role in the prevention of vascular aging process. It is a promising therapeutic approach to ameliorate aging-related vascular dysfunction and cardiovascular diseases.

Aging induced by D-galactose aggravates cardiac dysfunction via exacerbating mitochondrial dysfunction in obese insulin-resistant rats

The prevalence of obesity and an aging population are increasing worldwide. Both obesity and aging are independently known to be associated with cardiac dysfunction. However, in obese insulin-resistant subjects, the effects of aging on metabolic status and cardiac and mitochondrial functions are not completely understood. We hypothesized that in the obese insulin-resistant condition, aging induced by D-galactose increases cardiac senescence markers and aggravates the impairment of metabolic parameters, cardiac and mitochondrial function, and increases oxidative stress, inflammation, apoptosis, and autophagy. Sixty-four male Wistar rats were fed with either normal diet (ND) or high-fat diet (HFD) for 12 weeks. Then, rats were divided into vehicle groups (0.9% NSS, subcutaneous injection (SC)) or D-galactose groups (150 mg/kg/day, SC). After 0.9%NSS or D-galactose treatment for 4 weeks and 8 weeks, metabolic and cardiac functions were determined. The heart was then removed to determine mitochondrial functions and enable biochemical studies. After 4 weeks of D-galactose injection, ND rats treated with D-galactose (NDD4), HFD rats treated with vehicle (HFV4), and HFD rats treated with D-galactose (HFD4) had reduced cardiac function, impaired cardiac mitochondrial function and autophagy, and increased oxidative stress, inflammation, and apoptosis. Interestingly, after 8 weeks, HFD rats treated with D-galactose (HFD8) had the worst impairment of cardiac and mitochondrial function, autophagy, and apoptosis in comparison to the other groups. Aging induced by D-galactose aggravated cardiac dysfunction in obese insulin-resistant rats through the worsening of cardiac mitochondrial function, autophagy, and increased apoptosis in a time-dependent manner.

Effect of Ginkgo biloba Extract EGb761 on Hippocampal Neuronal Injury and Carbonyl Stress of D-Gal-Induced Aging Rats

Background

Ginkgo biloba extract is widely studied for antiaging activities, but little is known about its antiaging mechanism of protein carbonylation. In order to verify carbonyl toxification (stress) hypothesis of aging, we have investigated the effects of EGb761 on hippocampal neuronal injury and carbonyl stress of aging rats.

Methods

Seventy-two Wister male rats were randomly assigned into six groups (n = 12), normal control (NC), model control (MC), vitamin E (VE, 60 mg/kg) group, EGb761 low doses (GBEL, 8.75 mg/kg), EGb761 moderate doses (GBEM, 17.5 mg/kg), and EGb761 high doses (GBEH, 35 mg/kg). Except the NC, the other groups were subject to subcutaneous administration of 0.5% D-gal (10 ml/kg/day) for 6 weeks to induce aging model. The study detected cognitive impairment in rats by Morris water maze test and the contents of superoxidase dismutase (SOD), malondialdehyde (MDA), total antioxidant capacity (T-AOC) by the related kits. The level of 4-hydroxy-2-nonenal (4-HNE) protein adducts in rat brain was detected, and the ultrastructure of hippocampus was observed.

Results

The EGb761 treatment groups significantly improved the spatial learning and memory of rats. Moreover, EGb761 treatment could reduce hippocampal neuronal damage based on histopathological and ultrastructural observation. Further studies have proved that these activities are remarkably related with the reducing level of MDA, protein carbonyl and lipofuscin, and 4-HNE protein expression, as well as the increasing of SOD and T-AOC content. Furthermore, EGb761 improves telomerase activity by detecting telomerase activity in the brain of aging rats.

Conclusion

Our data indicate that EGb761 is an effective agent against D-gal-induced hippocampal neuronal loss owing to its antioxidative as well as carbonyl stress properties. Meanwhile, the carbonylation hypothesis is confirmed that the high level of 4-HNE may cause age-related neurodegenerative disorders.

Effects of d-galactose-induced ageing on the heart and its potential interventions

Ageing is a strong independent risk factor for disability, morbidity and mortality. Post-mitotic cells including those in the heart are a particular risk to age-related deterioration. As the occurrence of heart disease is increasing rapidly with an ageing population, knowledge regarding the mechanisms of age-related cardiac susceptibility and possible therapeutic interventions needs to be acquired to prevent advancing levels of heart disease. To understand more about the ageing heart, numerous aged animal models are being used to explore the underlying mechanisms. Due to time-consuming for investigations involving naturally aged animals, mimetic ageing models are being utilized to assess the related effects of ageing on disease occurrence. d-galactose is one of the substances used to instigate ageing in various models, and techniques involving this have been widely used since 1991. However, the mechanism through which d-galactose induces ageing in the heart remains unclear. The aim of this review was to comprehensively summarize the current findings from in vitro and in vivo studies on the effects of d-galactose-induced ageing on the heart, and possible therapeutic interventions against ageing heart models. From this review, we hope to provide invaluable information for future studies and based on the findings from experiments involving animals, we can inform possible therapeutic strategies for the prevention of age-related heart diseases in clinical settings.

Exogenous H2S restores ischemic post-conditioning-induced cardioprotection through inhibiting endoplasmic reticulum stress in the aged cardiomyocytes

Background

A gasotransmitter hydrogen sulfide (H₂S) plays an important physiological and pathological role in cardiovascular system. Ischemic post-conditioning (PC) provides cardioprotection in the young hearts but not in the aged hearts. Exogenous H₂S restores PC-induced cardioprotection by inhibition of mitochondrial permeability transition pore opening and oxidative stress and increase of autophagy in the aged hearts. However, whether H₂S contributes to the recovery of PC-induced cardioprotection via down-regulation of endoplasmic reticulum stress (ERS) in the aged hearts is unclear.

Methods

The aged H9C2 cells (the cardiomyocytes line) were induced using H₂O₂ and were exposed to H/R and PC protocols. Cell viability was observed by CCK-8 kit. Apoptosis was detected by Hoechst 33342 staining and flow cytometry. Related protein expressions were detected through Western blot.

Results

In the present study, we found that 30 μM H₂O₂ induced H9C2 cells senescence but not apoptosis. Supplementation of NaHS protected against H/R-induced apoptosis, the expression of cleaved caspase-3 and cleaved caspase-9 and the release of cytochrome c. The addition of NaHS also counteracted the reduction of cell viability caused by H/R and decreased the expression of GRP 78, CHOP, cleaved caspase-12, ATF 4, ATF 6 and XBP-1 and the phosphorylation of PERK, eIF 2α and IRE 1α. Additionally, NaHS increased Bcl-2 expression. PC alone did not provide cardioprotection in H/R-treated aged cardiomyocytes, which was significantly restored by the supplementation of NaHS. The beneficial role of NaHS was similar to the supply of 4-PBA (an inhibitor of ERS), GSK2656157 (an inhibitor of PERK), STF083010 (an inhibitor of IRE 1α), respectively, during PC.

Conclusion

Our results suggest that the recovery of myocardial protection from PC by exogenous H₂S is associated with the inhibition of ERS via down-regulating PERK-eIF 2α-ATF 4, IRE 1α-XBP-1 and ATF 6 pathways in the aged cardiomyocytes.

Advances in the Studies of Ginkgo Biloba Leaves Extract on Aging-Related Diseases

The prevalence of degenerative disorders in public health has promoted in-depth investigations of the underlying pathogenesis and the development of new treatment drugs. Ginkgo biloba leaves extract (EGb) is obtained from Ginkgo biloba leaves and has been used for thousands of years. In recent decades, both basic and clinical studies have established the effects of EGb. It is widely used in various degenerative diseases such as cerebrovascular disease, Alzheimer's disease, macroangiopathy and more. Here, we reviewed several pharmacological mechanisms of EGb, including its antioxidant properties, prevention of mitochondrial dysfunctions, and effect on apoptosis. We also described some clinical applications of EGb, such as its effect on neuro and cardiovascular protection, and anticancer properties. The above biological functions of EGb are mainly focused on aging-related disorders, but its effect on other diseases remains unclear. Thus, through this review, we aim to encourage further studies on EGb and discover more potential applications.

Involvement of PINK1/Parkin-mediated mitophagy in AGE-induced cardiomyocyte aging

CONTEXT AND OBJECTIVES

Advanced glycation end products (AGEs) can induce senescence in cardiomyocytes. However, its underlying molecular mechanisms remain unknown.

METHODS

Neonatal rat cardiomyocytes were incubated with AGEs, and cellular senescence was evaluated by senescence-associated beta-galactosidase (SA-β-gal) activity and aging-associated p16 expression. In addition, mitophagic activity was evaluated by measuring the expression of the PINK1, Parkin, LC3 and p62 proteins. The mitophagy inhibitor cyclosporine A (CsA) or PINK1 siRNAs was then administered to cardiomyocytes to study the role of mitophagy in AGE-induced aging.

RESULTS

A significantly increased number of SA-β-gal positive cells and increased p16 protein levels were observed in cardiomyocytes treated with AGEs. Moreover, AGEs significantly increased the protein levels of PINK1 and Parkin as well as the LC3-II/LC3-I ratio, which occurred in a dose-dependent manner. However, the expression of p62 decreased significantly in the AGE group compared to the control. Surprisingly, both CsA and the knockdown of PINK1 by small-interfering RNA (siRNA) significantly decreased the LC3-II/LC3-I ratio and the PINK1 and Parkin protein levels in AGE-treated cardiomyocytes. Moreover, CsA treatment or knockdown of PINK1 expression attenuated the increased number of SA-β-gal positive cells and the upregulated p16 level in cardiomyocytes induced by AGEs.

CONCLUSIONS

PINK1/Parkin-mediated mitophagy is involved in the process of cardiomyocyte senescence induced by AGEs, and a reduction in mitophagic activity might be a promising approach to block the senescent state in cardiomyocytes.

Exogenous H2S contributes to recovery of ischemic post-conditioning-induced cardioprotection by decrease of ROS level via down-regulation of NF-κB and JAK2-STAT3 pathways in the aging cardiomyocytes

Background

Hydrogen sulfide (H₂S), a third member of gasotransmitter family along with nitric oxide and carbon monoxide, generated from mainly catalyzed by cystathionine-lyase, possesses important functions in the cardiovascular system. Ischemic post-conditioning (PC) strongly protects against the hypoxia/reoxygenation (H/R)-induced injury and apoptosis of cardiomyocytes. However, PC protection is ineffective in the aging cardiomyocytes. Whether H₂S restores PC-induced cardioprotection by decrease of reactive oxygen species (ROS) level in the aging cardiomyocytes is unknown.

Methods

The aging cardiomyocytes were induced by treatment of primary cultures of neonatal cardiomyocytes using d-galactose and were exposed to H/R and PC protocols. Cell viability was observed by CCK-8 kit. Apoptosis was detected by Hoechst 33342 staining and flow cytometry. ROS level was analyzed using spectrofluorimeter. Related protein expressions were detected through Western blot.

Results

Treatment of NaHS (a H₂S donor) protected against H/R-induced apoptosis, cell damage, the expression of cleaved caspase-3 and cleaved caspase-9, the release of cytochrome c (Cyt c). The supplementation of NaHS also decreased the activity of LDH and CK, MDA contents, ROS levels and the phosphorylation of IκBα, NF-κB, JNK2 and STAT3, and increased cell viability, the expression of Bcl-2, the activity of SOD, CAT and GSH-PX. PC alone did not provide cardioprotection in H/R-treated aging cardiomyocytes, which was significantly restored by the addition of NaHS. The beneficial role of NaHS was similar to the supply of N-acetyl-cysteine (NAC, an inhibitor of ROS), Ammonium pyrrolidinedithiocarbamate (PDTC, an inhibitor of NF-κB) and AG 490 (an inhibitor of JNK2), respectively, during PC.

Conclusion

Our results suggest that exogenous H₂S contributes to recovery of PC-induced cardioprotection by decrease of ROS level via down-regulation of NF-κB and JAK2/STAT3 pathways in the aging cardiomyocytes.

Exogenous hydrogen sulfide restores cardioprotection of ischemic post-conditioning via inhibition of mPTP opening in the aging cardiomyocytes

The physiological and pathological roles of hydrogen sulfide (H₂S) in the regulation of cardiovascular functions have been recognized. H₂S protects against the hypoxia/reoxygenation (H/R)-induced injury and apoptosis of cardiomyocytes, and ischemic post-conditioning (PC) plays an important role in cardioprotection from H/R injury in neonatal cardiomyocytes but not in aging cardiomyocytes. Whether H₂S is involved in the recovery of PC-induced cardioprotection in aging cardiomyocytes is unclear. In the present study, we found that both H/R and PC decreased cystathionine-γ-lyase (CSE) expression and the production rate of H₂S. Supplementation of NaHS protected against H/R-induced apoptosis, the expression of cleaved caspase-3 and cleaved caspase-9, the release of cytochrome c (Cyt c), and mPTP opening. The addition of NaHS also counteracted the reduction of cell viability caused by H/R and increased the phosphorylation of ERK1/2, PI3K, Akt, GSK-3β and mitochondrial membrane potential. Additionally, NaHS increased Bcl-2 expression, promoted PKC-ε translocation to the cell membrane, and activated mitochondrial ATP-sensitive K channels (mitoK_ATP). PC alone did not provide cardioprotection in H/R-treated aging cardiomyocytes, which was significantly restored by the supplementation of NaHS. In conclusion, our results suggest that exogenous H₂S restores PC-induced cardioprotection via the inhibition of mPTP opening by the activation of the ERK1/2-GSK-3β, PI3K-Akt-GSK-3β and PKC-ε-mitoK_ATP pathways in aging cardiomyocytes. These findings provide a novel target for the treatment of aging ischemic cardiomyopathy.

Protective effects of Gingko biloba extract 761 on myocardial infarction via improving the viability of implanted mesenchymal stem cells in the rat heart

When introduced into the infarcted heart, bone marrow‑derived mesenchymal stem cells (MSCs) prevent the heart from deleterious remodeling and improve its recovery. The aim of the present study was to investigate the effects of Ginkgo biloba extract (EGb) 761 on the infarcted myocardium microenvironment following MSC transplantation. The established rat myocardial infarction (MI) model, with implanted PKH‑26 marked MSCs (1x105 cells), were randomly divided into two groups: The control group (injected with normal saline) and the EGb 761 treatment group (injected with 100 mg/kg/day EGb 761). The following indices for cardiac function, including the extent of inflammation, oxidative stress, MSC apoptosis and MSC differentiation were measured 1, 2 and 7 days after treatment. The anti‑inflammatory effect of EGb 761 was observed by histological examination. Compared with the respective control group, the malondialdehyde content significantly decreased and the superoxide dismutase, catalase and glutathione peroxidase activity significantly increased in the EGb761‑treated groups. In addition, the apoptotic index gradually decreased (P<0.05) with the extension of MI time in the EGb761-treated groups compared to the respective control groups, suggesting that EGb761 exhbits anti-oxidative effects. In addition, the level of the Fas protein was positively correlated with the implanted MSC apoptotic ratio. Following 7 days of MSC transplantation with EGb 761 treatment, the expression of cTnI in PKH26‑labeled MSCs was observed in the transplanted myocardium. Cardiac function, including the ejection fraction, left ventricular end‑systolic pressure and dp/dtmax significantly increased, and the left ventricular end diastolic diameters, left ventricular end‑diastolic volumes and left ventricular end‑diastolic pressure significantly decreased (P<0.05, vs. the control group). The results demonstrated that EGb 761 is important in improving cardiac function and the infarcted myocardium microenvironment. The present study indicated that the protective effects of EGb 761 on the infarcted myocardium may be mediated by improving the viability and the differentiation of the implanted MSCs into cardiomyocytes.