The PI3K/Akt/mTOR signaling pathway plays a role in regulating aconitine-induced autophagy in mouse liver

A toxicological review of alkaloids

Alkaloids are naturally occurring compounds with complex structures found in natural plants. To further improve the understanding of plant alkaloids, this review focuses on the classification, toxicity and mechanisms of action, providing insight into the occurrence of alkaloid-poisoning events and guiding the safe use of alkaloids in food, supplements and clinical applications. Based on their chemical structure, alkaloids can be divided into organic amines, diterpenoids, pyridines, isoquinolines, indoles, pyrrolidines, steroids, imidazoles and purines. The mechanisms of toxicity of alkaloids, including neurotoxicity, hepatoxicity, nephrotoxicity, cardiotoxicity and cytotoxicity, have also been reviewed. Some cases of alkaloid poisoning have been introduced when used as food or clinically, including accidental food poisoning, excessive consumption, and poisoning caused by the improper use of alkaloids in a clinical setting, and the importance of safety evaluation was illustrated. This review summarizes the toxicity and mechanism of action of alkaloids and provides evidence for the need for the safe use of alkaloids in food, supplements and clinical applications.

Nephrotoxicity assessment of podophyllotoxin-induced rats by regulating PI3K/Akt/mTOR-Nrf2/HO1 pathway in view of toxicological evidence chain (TEC) concept

Adverse reactions to traditional Chinese medicine have hindered the healthy development and internationalization process of the traditional Chinese medicine industry. The critical issue that needs to be solved urgently is to evaluate the safety of traditional Chinese medicine systematically and effectively. Podophyllotoxin (PPT) is a highly active compound extracted from plants of the genus Podophyllum such as Dysosma versipellis (DV). However, its high toxicity and toxicity to multiple target organs affect the clinical application, such as the liver and kidney. Based on the concurrent effects of PPT's medicinal activity and toxicity, it would be a good example to conduct a systematic review of its safety. Therefore, this study revolves around the Toxicological Evidence Chain (TEC) concept. Based on PPT as the main toxic constituent in DV, observe the objective toxicity impairment phenotype of animals. Evaluate the serum biochemical indicators and pathological tissue sections for substantial toxic damage results. Using metabolomics, lipidomics, and network toxicology to evaluate the nephrotoxicity of PPT from multiple perspectives systematically. The results showed that PPT-induced nephrotoxicity manifested as renal tubular damage, mainly affecting metabolic pathways such as glycerophospholipid metabolism and sphingolipid metabolism. PPT inhibits the autophagy process of kidney cells through the PI3K/Akt/mTOR and Nrf2/HO1 pathways and induces the activation of oxidative stress in the body, thereby causing nephrotoxic injury. This study fully verified the feasibility of the TEC concept for the safety and toxicity evaluation of traditional Chinese medicine. Provide a research template for systematically evaluating the safety of traditional Chinese medicine.

Mingmu Xiaoyao granules regulate the PI3K/Akt/mTOR signaling pathway to reduce anxiety and depression and reverse retinal abnormalities in rats

Objective: To investigate the effects of Mingmu Xiaoyao granules (MMXY) on the morphology and function of the retina and the mechanism of PI3K/Akt/mTOR pathway-related proteins in rats with anxiety and depression induced by chronic unpredictable mild stress (CUMS).

Methods: Fifty-two male Sprague Dawley rats were randomly allocated to either a control (n = 14) or a simulated CUMS group (n = 38). The CUMS model was established successfully at 4 weeks. Six rats in each group were randomly selected to be sacrificed and their retinas isolated for histological examination. At 5 weeks, rats in the CUMS group were randomly allocated to the following groups: Model (CUMS + pure water), MMXY-H (CUMS + MMXY 7.2 g/kg/d), MMXY-L (CUMS + MMXY 3.6 g/kg/d), and CBZ (CUMS + Carbamazepine 20 mg/kg/d), with eight rats in each group. All rats were given the relevant intervention once a day. At 12 weeks, sucrose preference and open field tests were performed to evaluate the anxiety and depression status of rats. In live rats, optical coherence tomography angiography was used to measure retinal thickness and blood flow, while electroretinograms (ERGs) and visual evoked potentials (VEPs) were used to evaluate retinal function. The next day, the specimens were sacrificed for serological, histological, immunofluorescence, Western blot and transmission electron microscopy examinations to explore the mechanism of MMXY in CUMS rats.

Results: MMXY improved the anxiety and depression-like behavior of rats. Results of optical coherence tomography angiography showed that MMXY improved retinal inner thickness and blood flow in CUMS rats. MMXY improved the amplitude of a- and b-waves in the scotopic and photopic ERG, as well as N2 and P2 peak time and amplitude in the flash-VEP in CUMS rats. Retinal histological staining and transmission electron microscopy showed that MMXY reversed retinal morphology and ultrastructure in CUMS rats. MMXY reduced the expression of Beclin1 and LC3I/II proteins, regulated the PI3K/Akt/mTOR pathway, inhibited autophagy, and had a protective effect on the retina in CUMS rats.

Conclusion: MMXY may effectively improve retinal morphology and function as well as anxiety and depression-like behaviors in CUMS rats by regulating the PI3K/Akt/mTOR signaling pathway.

Advances on pharmacology and toxicology of aconitine

Aconitum alkaloids are considered to be the characteristic bioactive ingredients of Aconitum species, which are widely applied to the treatment of diverse diseases, and aconitine (AC) is found in most Aconitum plants. Research evidence shows that low-dose AC has a good therapeutic potential in heart failure, myocardial infarction, neuroinflammatory diseases, rheumatic diseases, and tumors, which has become one of the hotspots in global research in recent years. However, the cardiotoxicity and neurotoxicity of AC have also attracted extensive attention. Excessive use of AC always induces ventricular tachyarrhythmia and heart arrest, even can be potentially lethal. Therefore, AC cannot simply be regarded as a good medicine or a toxicant, but its underlying curative and toxic properties remained chaos. In order to dig the unique pharmacological value of AC while preventing its toxicity, the pharmacological activities and toxic effects of AC were summarized in this paper, providing new insight into the safe and effective use of AC in clinical practice.

Tandem mass tag labeled quantitative proteomic analysis of differential protein expression on total alkaloid of Aconitum flavum Hand.-Mazz. against melophagus ovinus

Melophagus ovinus disease is a common ectoparasitosis, which can lead to a decrease in animal production performance, product quality, and even death. Aconitum flavum Hand.-Mazz. has many pharmacological activities including insecticidal, heat-clearing, analgesic, and dehumidifying. However, there are few researches focused on the effects and related mechanism of Aconitum flavum Hand.-Mazz. in killing Melophagus ovinus. In this study, 11 alkaloids of Aconitum flavum Hand.-Mazz. were detected, and its total alkaloid activity was determined. The results showed when the total alkaloid concentration was 64 mg/ml and the treatment time was 16 h, the killing rate of Melophagus ovinus reached 100%. Through the observation of the differences in the surface of Melophagus ovinus in each experimental group, it was found that the morphology of the posterior end of the female Melophagus ovinus in the alkaloid treatment group was significantly different from that of the blank and positive control groups, and most of the epidermal tissue was obsessive and missing. Moreover, the enzyme activity determination results of 64 mg/ml group were significantly different when compared with the normal control group, while there was no significant difference in other groups. Then, the Melophagus ovinus gene library was established by the unreferenced genome transcriptome sequencing, the proteomic comparison was performed using tandem mass tag labeled protein detection technology, and finally, the samples were quantitatively analyzed by liquid chromatography-mass spectrometry tandem and bioinformatics methods. Based on the above experimental results, it was speculated that Aconitum flavum Hand.-Mazz. total alkaloids may cause the imbalance of protein disulfide isomerase expressions by affecting the regulation of Hsp40 cellular protein homeostasis and the oxidation of protein disulfide isomerase and related proteins. This would affect the selective recognition of signal sequence, the targeted transport of Sec 61, and the correct folding of the three-dimensional structure of amino acid chain, weakening the clearance of amino acid chains that cannot be correctly folded and eventually resulting in the killing of Melophagus ovinus. This study preliminarily revealed the mechanism of Aconitum flavum Hand.-Mazz. total alkaloids against Melophagus ovinus and provided a theoretical basis for the screening of Melophagus ovinus action targets and the development of new veterinary drugs.

Aconitine: A review of its pharmacokinetics, pharmacology, toxicology and detoxification

ETHNOPHARMACOLOGICAL RELEVANCE

Aconitine, a C₁₉-norditerpenoid alkaloid, derives from many medicinal plants such as Aconitum carmichaelii Debx. (Chinese:), Aconitum kusnezoffii Reichb (Chinese:), which were used to rheumatic fever, painful joints and some endocrinal disorders.

AIMS OF THE REVIEW

The present paper reviews research progress relating to the pharmacokinetics, physiological and pathological processes of aconitine, while some promising research direction and the detoxification of aconitine are also discussed.

MATERIALS AND METHODS

The accessible literature on aconitine, from 1990 to 2020, obtained from published materials of electronic databases, such as SCI finder, PubMed, Web of Science, Science Direct, Springer and Google Scholar was systematically analyzed.

RESULTS

In this review, we address the pharmacokinetics of aconitine, as well as its pharmacological effects including anti-cancer, anti-inflammatory, anti-virus, immunoregulation, analgesic, insecticide and inhibition of androgen synthesis. Further, we summarize the toxicity of aconitine such as cardiotoxicity and neurotoxicity, on which we strikingly focus on the ways to reduce the toxicity of aconitine based.

CONCLUSIONS

Aconitine plays an vital role in a wide range of physiological and pathological processes and we can reduce the toxicity of aconitine by compatibility and hydrolysis. Although some issues still exist, such as the correlative relationship between the dose and toxicity of aconitine not being clear, our review may provide new ideas for the application of aconitine in the treatment of related diseases.

An insight into current advances on pharmacology, pharmacokinetics, toxicity and detoxification of aconitine

Aconitine is a diterpenoid alkaloid, which mainly exists in the plants of Aconitum. In the last decade, a plethora of studies on the pharmacological activities of aconitine has been conducted and demonstrated that aconitine possessed an extensive range of pharmacological activities such as anti-tumor, anti-inflammatory, analgesic, local anesthesia, and immunomodulatory effects. Pharmacokinetic studies indicated that aconitine may have the characteristics of poor bioavailability, wide distribution, and slow elimination. However, studies have also found that aconitine has toxic effects on the heart, nerves, embryos, etc. Therefore, we believe that aconitine may not be suitable for heart patients and pregnant women to treat related diseases. It is important to note that all of these pharmacological effects require further high-quality studies to determine the clinical efficacy of aconitine. This review aims to summarize the advances in pharmacological, pharmacokinetics, toxicity, and detoxification of aconitine in the last decade with an emphasis on its anti-tumor and anti-inflammatory activities, to provide researchers with the latest information and point out the limitations of relevant research at the current stage and the aspects that should be strengthened in future research.

Allethrin Promotes Apoptosis and Autophagy Associated with the Oxidative Stress-Related PI3K/AKT/mTOR Signaling Pathway in Developing Rat Ovaries

The increased concern regarding the reduction in female fertility and the impressive numbers of women undergoing fertility treatment support the existence of environmental factors beyond inappropriate programming of developing ovaries. Among these factors are pyrethroids, which are currently some of the most commonly used pesticides worldwide. The present study was performed to investigate the developmental effects of the pyrethroid-based insecticide allethrin on ovarian function in rat offspring in adulthood. We mainly focused on the roles of oxidative stress, apoptosis, autophagy and the related pathways in ovarian injury. Thirty-day-old Wistar albino female rats were intragastrically administered 0 (control), 34.2 or 68.5 mg/kg body weight allethrin after breeding from Day 6 of pregnancy until delivery. We found that allethrin-induced ovarian histopathological damage was accompanied by elevations in oxidative stress and apoptosis. Interestingly, the number of autophagosomes in allethrin-treated ovaries was higher, and this increase was correlated with the upregulated expression of genes and proteins related to the autophagic marker LC-3. Furthermore, allethrin downregulated the expression of PI3K, AKT and mTOR in allethrin-treated ovaries compared with control ovaries. Taken together, the findings of this study suggest that exposure to the pyrethroid-based insecticide allethrin adversely affects both the follicle structure and function in rat offspring during adulthood. Specifically, allethrin can induce excessive oxidative stress and defective autophagy-related apoptosis, probably through inactivation of the PI3K/AKT/mTOR signaling pathway, and these effects may contribute to ovarian dysfunction and impaired fertility in female offspring.

Autophagy is required for the promoting effect of angiogenic factor with G patch domain and forkhead-associated domain 1 (AGGF1) in retinal angiogenesis

OBJECTIVE

To investigate the effect of angiogenic factor with G patch domain and forkhead-associated domain 1 (AGGF1) on retinal angiogenesis in ischemic retinopathy and its association with autophagy.

METHODS

RF/6A cells were divided into the control group, hypoxia group and high-glucose group, and the expression of AGGF1 in cells was detected. C57BL/6 J mice were divided into the control group, oxygen-induced retinopathy (OIR) group and diabetic retinopathy (DR) group, and AGGF1 expression in the retina was observed. RF/6A cells were then divided into the control group and different AGGF1 concentration groups, and the expression of autophagy marker, LC3 was detected. Then, RF/6A cells were divided into the control group, AGGF1 group, 3-methyladenine (3-MA, an early autophagy inhibitor) + AGGF1 group and chloroquine (CQ, a late autophagy inhibitor) + AGGF1 group, and the expression of autophagy markers, LC3 and p62, autophagic flux, as well as was key signaling pathway proteins in autophagy, PI3K, AKT, and mTOR was detected. Finally, the cell proliferation, migration and tube formation were detected in the four groups.

RESULTS

AGGF1 expression in RF/6A cells and in the retinas of OIR and DR mouse model was found to be increased in the state of hypoxic and high glucose condition. AGGF1 treatment led to increased expressions of LC3 and decreased p62; therby induced autophagic flux, and the phosphorylation of PI3K, AKT and mTOR was down-regulated in RF/6A cells. When autophagy was inhibited by 3-MA or CQ, confirmed by corresponding changes of these indicators of autophagy, cellular proliferation, migration and tube formation of RF/6A cells were weakened by AGGF1 treatment when compared with that of AGGF1 treatment alone.

CONCLUSION

This study experimentally revealed that AGGF1 activates autophagy to promote angiogenesis for ischemic retinopathy and inhibition of PI3K/AKT/mTOR pathway may be involved in the activation of autophagy by AGGF1.

A systematic review of pharmacological activities, toxicological mechanisms and pharmacokinetic studies on Aconitum alkaloids

The tubers and roots of Aconitum (Ranunculaceae) are widely used as heart medicine or analgesic agents for the treatment of coronary heart disease, chronic heart failure, rheumatoid arthritis and neuropathic pain since ancient times. As a type of natural products mainly extracted from Aconitum plants, Aconitum alkaloids have complex chemical structures and exert remarkable biological activity, which are mainly responsible for significant effects of Aconitum plants. The present review is to summarize the progress of the pharmacological, toxicological, and pharmacokinetic studies of Aconitum alkaloids, so as to provide evidence for better clinical application. Research data concerning pharmacological, toxicological and pharmacokinetic studies of Aconitum alkaloids were collected from different scientific databases (PubMed, CNKI, Google Scholar, Baidu Scholar, and Web of Science) using the phrase Aconitum alkaloids, as well as generic synonyms. Aconitum alkaloids are both bioactive compounds and toxic ingredients in Aconitum plants. They produce a wide range of pharmacological activities, including protecting the cardiovascular system, nervous system, and immune system and anti-cancer effects. Notably, Aconitum alkaloids also exert strong cardiac toxicity, neurotoxicity and liver toxicity, which are supported by clinical studies. Finally, pharmacokinetic studies indicated that cytochrome P450 proteins (CYPs) and efflux transporters (ETs) are closely related to the low bioavailability of Aconitum alkaloids and play an important role in their metabolism and detoxification in vivo.

Systematically explore the potential hepatotoxic material basis and molecular mechanism of Radix Aconiti Lateralis based on the concept of toxicological evidence chain (TEC)

Radix aconiti lateralis (Fuzi) is widely used in China as a traditional Chinese medicine for the treatment of asthenia, pain and inflammation. However, its toxic alkaloids often lead to adverse reactions. Currently, most of the toxicity studies on Fuzi are focused on the heart and nervous system, and more comprehensive toxicity studies are needed. In this study, based on the previous reports of Fuzi hepatotoxicity, serum pharmacochemistry and network toxicology were used to screen the potential toxic components of Heishunpian(HSP), a processed product of Fuzi, and to explore the possible mechanism of HSP-induced hepatotoxicity. The results obtained are expressed based on the toxicological evidence chain (TEC). It was found that 22 potential toxic components screened can affect Th17 cell differentiation, Jak-STAT signaling pathway, glutathione metabolism, and other related pathways by regulating AKT1, IL2, F2, GSR, EGFR and other related targets, which induces oxidative stress, metabolic disorders, cell apoptosis, immune response, and excessive release of inflammatory factors, eventually inducing liver damage in rats. This is the first study on HSP-induced hepatotoxicity based on the TEC concept, providing references for further studies on the toxicity mechanism of Fuzi.

2,3,5,4'-Tetrahydroxy-stilbene-2-O-beta-d-glucoside induces autophagy-mediated apoptosis in hepatocytes by upregulating miR-122 and inhibiting the PI3K/Akt/mTOR pathway: implications for its hepatotoxicity

CONTEXT

The potential hepatotoxicity of Polygoni Multiflori Radix (PMR) has attracted much attention, but the specific mechanism of inducing hepatotoxicity is still unclear due to the complexity of its components.

OBJECTIVE

This study investigated the specific mechanism by which 2,3,5,4'-tetrahydroxy-stilbene-2-O-β-d-glucoside (TSG) regulates hepatotoxicity.

MATERIALS AND METHODS

The toxic effects of TSG (10, 100, 1000 μg/mL) on WRL-68 cells were examined using MTT, flow cytometry, and LDH assay after 24 h of incubation. Untreated cells served as the control. Gene and protein expression levels were determined by quantitative real-time PCR and Western blot, respectively. Immunofluorescence analysis was conducted to investigate the expression of light chain 3 (LC3). Luciferase activity assay was used to assess the targeted regulation of RUNX1 by miR-122.

RESULTS

The half maximal inhibitory concentration (IC50) of TSG in WRL-68 cells was calculated as 1198.62 μg/mL. TSG (1000 μg/mL) inhibited cell viability and LDH activity and promoted WRL-68 cell apoptosis by inducing autophagy. Subsequent findings showed that TSG induced autophagy and promoted apoptosis in WRL-68 cells by downregulating the levels of p-PI3K, p-Akt, and p-mTOR proteins, while RUNX1 overexpression rescued this inhibition. Additionally, the effect of TSG on hepatocyte apoptosis was reversed by miR-122 knockdown. Furthermore, bioinformatics and dual luciferase reporter assay results indicated that miR-122 targeted RUNX1.

DISCUSSION AND CONCLUSIONS

Our data demonstrate for the first time that TSG regulates hepatotoxicity, possibly by upregulating miR-122 and inhibiting the RUNX1-mediated PI3K/Akt/mTOR pathway to promote autophagy and induce hepatocyte apoptosis. Further in vivo research is necessary to verify our conclusion.

Ketogenic diet induces autophagy to alleviate bleomycin-induced pulmonary fibrosis in murine models

AIM OF THE STUDY

Ketogenic diet (KD) has been identified as an effective strategy in treating multiple diseases. KD is capable of inducing autophagy which is an important therapeutic target for pulmonary fibrosis (PF). This study aimed to investigate the effect of KD treatment on PF progression. Materials and Methods: Intratracheal instillation of bleomycin (BLM, 5 mg/kg) to establish PF model in male Kunming mice fed either KD or standard diet. The survival of mice was recorded every day for 3 weeks. The pulmonary tissues were weighed on day 21 and the pulmonary index was calculated. The histopathological changes of pulmonary tissues were analyzed by hematoxylin and eosin staining and Masson staining, and the collagen deposition by hydroxyproline assay. Then the content of proinflammatory factors in pulmonary tissues was measured using enzyme-linked immunosorbent assay, and the expression of profibrogenic cytokines, autophagy markers and PI3K/AKT/mTOR pathway-related proteins in pulmonary tissues using western blotting or immunohistochemistry. Results: KD treatment significantly restored the BLM-induced increase of pulmonary index and had a tendency to increase the survival rate of PF mice. Furthermore, KD treatment restored the BLM-induced damage of alveolar structure, infiltration of inflammatory cells and collagen deposition and decreased hydroxyproline content. In addition, the BLM-induced secretion of tumor necrosis factor-alpha, interleukin-6 and interleukin-1β and expression of transforming growth factor β1, phospho-Smad2/3, connective tissue growth factor, α-smooth muscle actin and collagen type III alpha 1 chain were inhibited by KD. KD treatment also up-regulated the expression of light chain 3 II/I and Beclin1 and down-regulated the expression of p62, phospho-AKT, phospho-mTOR and phospho-p70S6K, suggesting that KD induced autophagy and suppressed the BLM-induced activation of PI3K/AKT/mTOR signaling pathway. Conclusions: These findings indicate that KD can alleviate PF in vivo by regulating autophagy and PI3K/AKT/mTOR signaling pathway, which provides a novel therapeutic strategy for PF.

Zearalenone disrupts the placental function of rats: A possible mechanism causing intrauterine growth restriction

Zearalenone is an estrogenic mycotoxin produced by a variety of Fusarium fungi. There is evidence that exposure to zearalenone can cause intrauterine growth restriction, but little is known about the mechanism in the rat placenta caused by zearalenone. From gestational day 14-21, female Sprague Dawley rats (60 days old) were gavaged with zearalenone (0, 2.5, 5, 10, and 20 mg/kg/day body weight). Zearalenone dose-dependently reduced serum LH and FSH levels of dams at ≥ 5 mg/kg. RNA-seq and qPCR showed that zearalenone significantly down-regulated Slc38a1 expression at 2.5 mg/kg, Echs1 and Pc at 10 mg/kg, as well as Slc1a5, Cd36, Ldlr, Hadhb, and Cyp17a1 expression at a dose of 20 mg/kg, while it up-regulated the expression of Notch signal (Dvl1 and Jag 1). After zearalenone treatment, their proteins showed a similar trend. Zearalenone reduced the phosphorylation of AKT1, ERK1/2, and mTOR at 5 mg/kg or higher and 4EBP1 at 5 mg/kg. Zearalenone also increased BECLIN1, LC3B, and p62 levels and elevated BAX/BCL2 and CASP3/PROCASP3 ratios. In conclusion, zearalenone disrupts placental function such as reduction of nutrient transport and lipid metabolism possibly via AKT1/ERK1/2/mTOR-mediated autophagy and apoptosis.

Repression of deoxynivalenol-triggered cytotoxicity and apoptosis by mannan/β-glucans from yeast cell wall: Involvement of autophagy and PI3K-AKT-mTOR signaling pathway

Deoxynivalenol (DON) is the most common trichothecene distributed in food and feed. So far, much work has focused on investigating the cytotoxicity of DON, while there is few researches aimed at intervening in the toxic impacts on humans and livestock posed by DON. The objective of this study is to investigate the underlying mechanism of biomacromolecules mannan/β-glucans from yeast cell wall (BYCW) for their potency to impede the cytotoxicity and apoptosis caused by DON with porcine jejunum epithelial cell lines (IPEC-J2) used as a cell injury model. We analyzed the cell morphology, cell activity, oxidative stress, fluorescence intensity and expressions of proteins relevant to autophagy, apoptosis and PI3K-AKT-mTOR signaling pathway by using inverted microscopy, MTS, reactive oxygen species (ROS), glutathione (GSH) and malondialdehyde (MDA) assay, Annexin V-FITC / propidium iodide (PI) double staining and Western blot assay. The consequent data demonstrated that in the presence of BYCW, the cell morphology and activity were relatively ameliorated and that the oxidation damage was attenuated with DON-induced autophagy concomitantly decreased, which, furthermore, was found involved in the positive regulation on PI3K-AKT-mTOR signaling pathway by BYCW. In a word, BYCW possess an ability to repress the cytotoxicity and apoptosis induced by DON through the inhibition of autophagy via activating PI3K-AKT-mTOR signaling pathway.

Kappa opioid receptors internalization is protective against oxygen-glucose deprivation through β-arrestin activation and Akt-mediated signaling pathway

Hypoxia induces reversible κ-opioid receptor (KOR) internalization similar to the internalization that is induced by KOR agonists. In the current study, we demonstrate that this KOR internalization is a protective mechanism via the β-arrestin specific pathway in an oxygen-glucose deprivation (OGD) model. Mouse neuroblastoma Neuro2A cells were stably transfected with mouse KOR-tdTomato fusion protein (N2A-mKOR-tdT cells). Various concentrations of salvinorin A (SA), a highly selective KOR agonist, were given in the presence and absence of norbinaltorphimine (norBNI), which is a KOR antagonist, or Dyngo-4a (internalization inhibitor) or API-2 (Akt/Protein kinase B signaling inhibitor-2). Various concentrations of SA and RB-64 (22-thiocyanatosalvinorin A, selective for the G protein signaling pathway) were administered both in normoxic and hypoxic conditions. Autophagosomes and ultrastructural components of cells were observed using transmission electron microscopy (TEM). Cell viability, severity of cell injury, and levels of proteins related to the Akt signaling pathway were evaluated using live cell counting (by Cell Counting Kit-8), the lactic acid dehydrogenase (LDH) release rate, and Western blot analysis, respectively. SA promoted cell survival and attenuated OGD-induced cell injury. The Akt signaling pathway is activated by SA. KOR internalization, when blocked by norBNI or Dyngo-4a, increased LDH release and decreased cell viability under OGD. Treatment with SA significantly inhibited autophagy, and the effects of SA on autophagy were reversed by API-2 pretreatment. RB-64 in a low concentration without β-arrestin recruitment did not reduce LDH release and increase cell viability as observed with SA. KOR internalization through β-arrestin activation is a protective mechanism against OGD. The Akt pathway might play a critical role in modulating these protective effects by inhibiting autophagy.

Role of p75 neurotrophin receptor in neuronal autophagy in intracerebral hemorrhage in rats through the mTOR signaling pathway

Rupture of weakened blood vessels could lead to severe intracerebral hemorrhage (ICH) and brain injuries. This study was designed to explore the roles of p75 neurotrophin receptor (p75^NTR) in neuronal autophagy in ICH rats. An ICH rat model was established, and then gain and loss of functions of p75^NTR in rat tissues were performed. Then, the pathologic morphology, water content, and inflammation in brain tissues were assessed. Western blot analysis was applied to detect the levels of inflammatory proteins, apoptosis- and autophagy-related proteins, and the mammalian target of rapamycin (mTOR) pathway-related proteins. Neuronal autophagy was further measured with mTOR activated. In vitro experiments were also performed on brain microvascular endothelial cells (BMECs) and astrocytes. Consequently, we found p75^NTR knockdown improved the pathologic morphology with reduced neuron damage, water content, permeability of blood-brain barrier and inflammation in ICH rat brain tissues. Besides, Knockdown of p75^NTR decreased neuronal apoptosis and inactivated mTOR signaling pathway, but it elevated the levels of autophagy-related proteins. In vivo results were reproduced in in vitro experiments. This study demonstrated that knockdown of p75^NTR could promote neuronal autophagy and reduce neuronal apoptosis via inactivating the mTOR pathway. We hope these findings could provide new therapeutic options for ICH treatment.

Impaired function of aorta and perivascular adipose tissue in IL-18-deficient mice

IL-18 is ubiquitously produced by both hematopoietic and non-hematopoietic cells. The present study examined the thoracic aorta, including the surrounding perivascular adipose tissue (PVAT), of IL-18KO mice from functional and histological perspectives. IL-18KO mice exhibited raised blood pressure compared with wild-type mice. Echocardiographic examination showed a thickened vascular wall and narrowed vascular diameter of the aorta. Examination by the Magnus test demonstrated dysfunction of endothelial cells (ECs) in the IL-18KO thoracic aorta and impairment of the anticontractile function of IL-18KO PVAT. Histological examination showed no inflammatory lesions in the aorta but indicated progressive fibrosis in the vessel and conversion of PVAT from brown adipose tissue-like features to white adipose tissue-like features. Electron microscopic observation suggested several deformed mitochondria in the aorta and vacuole-like structures in ECs from IL-18KO mice. In addition, activity of complex IV was lower and production of reactive oxygen species was augmented in the mitochondria of IL-18KO aorta. Although expression of LC3 B was higher, rapamycin-induced autophagy flux was impaired in the IL-18KO PVAT. Moreover, Western blot analysis revealed that LAMP 1/2 was increased in IL-18KO PVAT, and measurement of cathepsin-D activity indicated decreased levels in IL-18KO PVAT. The IL-18KO thoracic aorta thus showed defects in physiological functions related to histological alterations, and the inflammasome/IL-18 system was suggested to play a protective role in cardiovascular cells, probably through quality control of mitochondria via promotion of autophagosome/autophagolysosome formation.NEW & NOTEWORTHY IL-18 deficiency caused aortic abnormalities in terms of morphology and functions in parallel with an accumulation of damaged mitochondria and anomalous turnover of protein complexes, such as PGC-1 and LAMP1 and -2 in PVAT. These findings suggested that IL-18 plays roles in maintaining the homeostasis of vessels and PVAT around the aorta, possibly by promoting autophagy.

[Effects of mitochondrial aldehyde dehydrogenase 2 on autophagy-associated proteins in neonatal rat myocardial fibroblasts cultured in high glucose]

OBJECTIVE

To investigate whether autophagy mediates the effects of aldehyde dehydrogenase 2 (ALDH2) on the proliferation of neonatal rat cardiac fibroblasts cultured in high glucose.

METHODS

Cardiac fibroblasts were isolated from neonatal (within 3 days) SD rats and subcultured. The fibroblasts of the third passage, after identification with immunofluorescence staining for vimentin, were treated with 5.5 mmol/L glucose (control group), 30 mmol/L glucose (high glucose group), or 30 mmol/L glucose in the presence of Alda-1 (an ALDH2 agonist), daidzin (an ALDH2 2 inhibitor), or both. Western blotting was employed to detect ALDH2, microtubule-associated protein 1 light chain 3B subunit (LC3B) and Beclin-1 in the cells, and a hydroxyproline detection kit was used for determining hydroxyproline content in cell culture medium; CCK- 8 kit was used for assessing the proliferation ability of the cardiac fibroblasts after the treatments.

RESULTS

Compared with the control cells, the cells exposed to high glucose exhibited obviously decreased expressions of ALDH2, Beclin-1 and LC3B and increased cell number and hydroxyproline content in the culture medium. Treatment of the high glucose-exposed cells with Alda-1 significantly increased Beclin-1, LC3B, and ALDH2 protein expressions and lowered the cell number and intracellular hydroxyproline content, whereas the application of daidzin resulted in reverse changes in the expressions of ALDH2, Beclin-1 and LC3B, viable cell number and intracellular hydroxyproline content in high glucose-exposed cells.

CONCLUSIONS

Mitochondrial ALDH2 inhibits the proliferation of neonatal rat cardiac fibroblasts induced by high glucose, and the effect is possibly mediated by the up-regulation of autophagy-related proteins Beclin-1 and LC3B.