The activation of spliced X-box binding protein 1 by isorhynchophylline therapy improves diabetic encephalopathy.

The primary symptom of diabetic encephalopathy (DE), a kind of central diabetic neuropathy caused by diabetes mellitus (DM), is cognitive impairment. In addition, the tetracyclic oxindole alkaloid isorhynchophylline (IRN) helps lessen cognitive impairment. However, it is still unclear how IRN affects DM and DE and what mechanisms are involved. The effectiveness of IRN on brain insulin resistance was carefully examined in this work, both in vitro and in vivo. We found that IRN accelerates spliced form of X-box binding protein 1 (sXBP1) translocation into the nucleus under high glucose conditions in vitro. IRN also facilitates the nuclear association of pCREB with sXBP1 and the binding of regulatory subunits of phosphatidylinositol 3-kinase (PI3K) p85α or p85ß with XBP1 to restore high glucose impairment. Also, IRN treatment improves high glucose-mediated impairment of insulin signaling, endoplasmic reticulum stress, and pyroptosis/apoptosis by depending on sXBP1 in vitro. In vivo studies suggested that IRN attenuates cognitive impairment, ameliorating peripheral insulin resistance, activating insulin signaling, inactivating activating transcription factor 6 (ATF6) and C/EBP homology protein (CHOP), and mitigating pyroptosis/apoptosis by stimulation of sXBP1 nuclear translocation in the brain. In summary, these data indicate that IRN contributes to maintaining insulin homeostasis by activating sXBP1 in the brain. Thus, IRN is a potent antidiabetic agent as well as an sXBP1 activator that has promising potential for the prevention or treatment of DE.

Autocrine S100B in astrocytes promotes VEGF-dependent inflammation and oxidative stress and causes impaired neuroprotection.

Minimal hepatic encephalopathy (MHE) is strongly associated with neuroinflammation. Nevertheless, the underlying mechanism of the induction of inflammatory response in MHE astrocytes remains not fully understood. In the present study, we investigated the effect and mechanism of S100B, a predominant isoform expressed and released from mature astrocytes, on MHE-like neuropathology in the MHE rat model. We discovered that S100B expressions and autocrine were significantly increased in MHE rat brains and MHE rat brain-derived astrocytes. Furthermore, S100B stimulates VEGF expression via the interaction between TLR2 and RAGE in an autocrine manner. S100B-facilitated VEGF autocrine expression further led to a VEGFR2 and COX-2 interaction, which in turn induced the activation of NFƙB, eventually resulting in inflammation and oxidative stress in MHE astrocytes. MHE astrocytes supported impairment of neuronal survival and growth in a co-culture system. To sum up, a comprehensive understanding of the role of S100B-overexpressed MHE astrocyte in MHE pathogenesis may provide insights into the etiology of MHE.

Hydrogen sulphide ameliorates dopamine-induced astrocytic inflammation and neurodegeneration in minimal hepatic encephalopathy.

It has been demonstrated that the action of dopamine (DA) could enhance the production of tumour necrosis factor-α (TNF-α) by astrocytes and potentiate neuronal apoptosis in minimal hepatic encephalopathy (MHE). Recently, sodium hydrosulfide (NaHS) has been found to have neuroprotective properties. Our study addressed whether NaHS could rescue DA-challenged inflammation and apoptosis in neurons to ameliorate memory impairment in MHE rats and in the neuron and astrocyte coculture system. We found that NaHS suppressed DA-induced p65 acetylation, resulting in reduced TNF-α production in astrocytes both in vitro and in vivo. Furthermore, decreased apoptosis was observed in neurons exposed to conditioned medium from DA + NaHS-challenged astrocytes, which was similar to the results obtained in the neurons exposed to TNF-α + NaHS, suggesting a therapeutic effect of NaHS on the suppression of neuronal apoptosis via the reduction of TNF-α level. DA triggered the inactivation of p70 S6 ribosomal kinase (S6K1) and dephosphorylation of Bad, resulting in the disaggregation of Bclxl and Bak and the release of cytochrome c (Cyt. c), and this process could be reversed by NaHS administration. Our work demonstrated that NaHS attenuated DA-induced astrocytic TNF-α release and ameliorated inflammation-induced neuronal apoptosis in MHE. Further research into this approach may uncover future potential therapeutic strategies for MHE.

New Measures for the Coronavirus Disease 2019 Response: A Lesson From the Wenzhou Experience.

As the outbreak of coronavirus disease 2019 (COVID-19) has spread globally, determining how to prevent the spread is of paramount importance. We reported the effectiveness of different responses of 4 affected cities in preventing the COVID-19 spread. We expect the Wenzhou anti-COVID-19 measures may provide information for cities around the world that are experiencing this epidemic.

Oridonin prevents insulin resistance-mediated cognitive disorder through PTEN/Akt pathway and autophagy in minimal hepatic encephalopathy.

Minimal hepatic encephalopathy (MHE) was characterized for cognitive dysfunction. Insulin resistance (IR) has been identified to be correlated with the pathogenesis of MHE. Oridonin (Ori) is an active terpenoid, which has been reported to rescue synaptic loss and restore insulin sensitivity. In this study, we found that intraperitoneal injection of Ori rescued IR, reduced the autophagosome formation and synaptic loss and improved cognitive dysfunction in MHE rats. Moreover, in insulin-resistant PC12 cells and N2a cells, we found that Ori blocked IR-induced synaptic deficits via the down-regulation of PTEN, the phosphorylation of Akt and the inhibition of autophagy. Taken together, these results suggested that Ori displays therapeutic efficacy towards memory deficits via improvement of IR in MHE and represents a novel bioactive therapeutic agent for treating MHE.

Dopamine Burden Triggers Cholesterol Overload Following Disruption of Synaptogenesis in Minimal Hepatic Encephalopathy.

The contribution of Dopamine (DA) to minimal hepatic encephalopathy (MHE) has been demonstrated. However, recent studies have revealed that cholesterol (CHO) treatment substantially increased the risk of dementia. The objectives of this study were to investigate whether CHO was induced by DA overload and its involvement in DA-induced cognitive impairment in MHE. Our study showed that DA treatment triggered CHO biosynthesis via the activation of JNK3/SREBP2 signaling pathway in primary cultured astrocytes. Conditioned media from DA-treated astrocytes increased CHO uptake by primary cultured neurons and disrupted synaptic formations; at the same time, inhibition of CHO synthesis and transportation from astrocytes diminished the disruption of synaptogenesis, which indicates the involvement of CHO in the perturbation of neural synaptogenesis in vitro. Secondary secretion of DA from primary cultured neurons was stimulated by CHO secreted from astrocytes. DA induced synergistic decreases of PPARγ/pERK/pCREB expressions in the presence of CHO in neurons, leading to synergistic synaptic impairment. Memory impairments were observed in MHE/DA-treated rats, which were partially rescued by atorvastatin (ATVS) treatment, confirming the involvement of CHO burden in vivo. Overall, our study suggests that DA overload triggers obvious CHO production from astrocytes. Excessive CHO in turn triggered neurons to secrete abundant DA and DA burden in combination with CHO overload elicit the cognitive decline and memory loss via PPARγ/ERK/CREB pathway in MHE.

Calpain inhibitor MDL28170 improves the transplantation-mediated therapeutic effect of bone marrow-derived mesenchymal stem cells following traumatic brain injury.

BACKGROUND: Studies have shown that transplantation of bone marrow-derived mesenchymal stem cells (BMSCs) protects against brain damage. However, the low survival number of transplanted BMSCs remains a pertinent challenge and can be attributed to the unfavorable microenvironment of the injured brain. It is well known that calpain activation plays a critical role in traumatic brain injury (TBI)-mediated inflammation and cell death; previous studies showed that inhibiting calpain activation is neuroprotective after TBI. Thus, we investigated whether preconditioning with the calpain inhibitor, MDL28170, could enhance the survival of BMSCs transplanted at 24 h post TBI to improve neurological function. METHODS: TBI rat model was induced by the weight-drop method, using the gravitational forces of a free falling weight to produce a focal brain injury. MDL28170 was injected intracranially at the lesion site at 30 min post TBI, and the secretion levels of neuroinflammatory factors were assessed 24 h later. BMSCs labeled with green fluorescent protein (GFP) were locally administrated into the lesion site of TBI rat brains at 24 h post TBI. Immunofluorescence and histopathology were performed to evaluate the BMSC survival and the TBI lesion volume. Modified neurological severity scores were chosen to evaluate the functional recovery. The potential mechanisms by which MDL28170 is involved in the regulation of inflammation signaling pathway and cell apoptosis were determined by western blot and immunofluorescence staining. RESULTS: Overall, we found that a single dose of MDL28170 at acute phase of TBI improved the microenvironment by inhibiting the inflammation, facilitated the survival of grafted GFP-BMSCs, and reduced the grafted cell apoptosis, leading to the reduction of lesion cavity. Furthermore, a significant neurological function improvement was observed when BMSCs were transplanted into a MDL28170-preconditioned TBI brains compared with the one without MDL28170-precondition group. CONCLUSIONS: Taken together, our data suggest that MDL28170 improves BMSC transplantation microenvironment and enhances the neurological function restoration after TBI via increased survival rate of BMSCs. We suggest that the calpain inhibitor, MDL28170, could be pursued as a new combination therapeutic strategy to advance the effects of transplanted BMSCs in cell-based regenerative medicine.

Baicalin reverses the impairment of synaptogenesis induced by dopamine burden via the stimulation of GABAAR-TrkB interaction in minimal hepatic encephalopathy.

BACKGROUND: It has been reported that D1 receptor (D1R) activation reduces GABAA receptor (GABAAR) current, and baicalin (BAI) displays therapeutic efficacy in diseases involving cognitive impairment. METHODS: We investigated the mechanisms by which BAI could improve DA-induced minimal hepatic encephalopathy (MHE) using immunoblotting, immunofluorescence, and co-immunoprecipitation. RESULTS: BAI did not induce toxicity on the primary cultured neurons. And no obvious toxicity of BAI to the brain was found in rats. DA activated D1R/dopamine and adenosine 3'5'-monophosphate-regulated phospho-protein (DARPP32) to reduce the GABAAR current; BAI treatment did not change the D1R/DARPP32 levels but blocked DA-induced reduction of GABAAR levels in primary cultured neurons. DA decreased the interaction of GABAAR with TrkB and the expression of downstream AKT, which was blocked by BAI treatment. Moreover, BAI reversed the decrease in the expression of GABAAR/TrkB/AKT and prevented the impairment of synaptogenesis and memory deficits in MHE rats. CONCLUSIONS: These results suggest that BAI has neuroprotective and synaptoprotective effects on MHE which are not related to upstream D1R/DARPP32 signaling, but to the targeting of downstream GABAAR signaling to TrkB.

Carnosine Inhibits the Proliferation of Human Cervical Gland Carcinoma Cells Through Inhibiting Both Mitochondrial Bioenergetics and Glycolysis Pathways and Retarding Cell Cycle Progression.

Carnosine has been demonstrated to play an antitumorigenic role in certain types of cancer. However, its underlying mechanism is unclear. In this study, the roles of carnosine in cell proliferation and its underlying mechanism were investigated in the cultured human cervical gland carcinoma cells HeLa and cervical squamous carcinoma cells SiHa. The results showed that carnosine exerted a significant inhibitory effect on the proliferation of HeLa cells, whereas its inhibitory action on the proliferation of SiHa cells was much weaker. Carnosine decreased the ATP content through inhibiting both mitochondrial respiration and glycolysis pathways in cultured HeLa cells but not SiHa cells. Carnosine reduced the activities of isocitrate dehydrogenase and malate dehydrogenase in TCA (tricarboxylic acid) cycle and the activities of mitochondrial electron transport chain complex I, II, III, and IV in HeLa cells but not SiHa cells. Carnosine also decreased the mRNA and protein expression levels of ClpP, which plays a key role in maintaining the mitochondrial function in HeLa cells. In addition, carnosine induced G1 arrest by inhibiting the G1-S phase transition in both HeLa and SiHa cells. Taken together, these findings suggest that carnosine has a strong inhibitory action on the proliferation of human cervical gland carcinoma cells rather than cervical squamous carcinoma cells. Mitochondrial bioenergetics and glycolysis pathways and cell cycle may be involved in the carnosine action on the cell proliferation in cultured human cervical gland carcinoma cells HeLa.

Dopamine induces glutamate accumulation in astrocytes to disrupt neuronal function leading to pathogenesis of minimal hepatic encephalopathy.

Minimal hepatic encephalopathy (MHE) is induced by elevated intracranial dopamine (DA). Glutamate (Glu) toxicity is known to be involved in many neurological disorders. In this study, we investigated whether DA increased Glu levels and collaborated with Glu to impair memory. We found that DA upregulated TAAR1, leading to reduced EAAT2 expression and Glu clearance in primary cortical astrocytes (PCAs). High DA increased TAAR1 expression, and high Glu increased AMPAR expression, inducing the activation of CaN/NFAT signaling and a decrease in the production of BDNF (Brain Derived Nerve Growth Factor)/NT3 (neurotrophin-3) in primary cortical neurons (PCNs). DA activated TAAR1 to downregulate EAAT2 and increase extracellular Glu levels in MHE. Additionally, DA together with Glu caused decreased production of neuronal BDNF/NT3 and memory impairment through the activation of CaN/NFAT signaling in MHE. From these findings, we conclude that DA increases Glu levels via interaction with TAAR1 and disruption of EAAT2 signaling in astrocytes, and DA interacting with TAAR1 and Glu interacting with AMPAR synergistically decreased the production of BDNF by activation of CaN/NFAT signaling to impair memory in MHE rats.

DA Negatively Regulates IGF-I Actions Implicated in Cognitive Function via Interaction of PSD95 and nNOS in Minimal Hepatic Encephalopathy.

Insulin-like growth factor I (IGF-I) has been positively correlated with cognitive ability. Cognitive decline in minimal hepatic encephalopathy (MHE) was shown to be induced by elevated intracranial dopamine (DA). The beneficial effect of IGF-I signaling in MHE remains unknown. In this study, we found that IGF-I content was reduced in MHE rats and that IGF-I administration mitigated cognitive decline of MHE rats. A protective effect of IGF-I on the DA-induced interaction between postsynaptic density protein 95 (PSD95) and neuronal nitric oxide synthase (nNOS) was found in neurons. Ribosomal S6 protein kinase (RSK) phosphorylated nNOS in response to IGF-I by recruiting extracellular signal-regulated kinase (ERK1/2). In turn, DA inactivated the ERK1/2/RSK pathway and stimulated the PSD95-nNOS interaction by downregulating IGF-I. Inhibition of the interaction between PSD95 and nNOS ameliorated DA-induced memory impairment. As DA induced deficits in the ERK1/2/RSK pathway and the interaction between PSD95 and nNOS in MHE brains, IGF-I administration exerted a protective effect via interruption of the interaction between PSD95 and nNOS. These results suggest that IGF-I antagonizes DA-induced cognitive loss by disrupting PSD95-nNOS interactions in MHE.

Dopamine Burden Induced the Inactivation of Sonic Hedgehog Signaling to Cognitive Decline in Minimal Hepatic Encephalopathy.

Minimal hepatic encephalopathy (MHE) is induced by elevated intracranial dopamine (DA). The relationship of the Shh pathway with memory loss in MHE, however, is elusive. In the current study, rats with MHE induced with DA displayed downregulation of the Shh pathway. Additionally, injection of Shh into MHE/DA-treated rats reversed downregulation of BDNF/NT3, whereas administration of cyclopamine (Cyc) enhanced the inhibition of expression of BDNF/NT3. Furthermore, naringin (Nrg) substantially prevented cognitive impairment in MHE/DA-treated rats and upregulated the Shh pathway, paralleling the elevated expression of BDNF/NT3. Overall, our results indicate that the Shh pathway can induce the expression of BDNF/NT3, and DA causes memory loss by inactivation of Shh pathway signaling to BDNF/NT3 in MHE rats, which is reversed by Nrg. Our study may provide new theory basis of pathogenesis and therapeutic target of MHE.

[Dopamine inhibits glutamate-uptake ability of astrocytes via TAAR1-EAAT2 pathway].

Objective To investigate the effect of dopamine (DA) on the glutamate (Glu)-uptake ability of astrocytes, and the role of trace amine-associated receptor 1-excitatory amino acid transporter 2 (TAAR1-EAAT2) signaling pathway in Glu uptake by astrocytes. Methods In the primary cultured astrocytes pretreated with DA, extracellular Glu levels were measured by the Amplex Red glutamic acid assay kit. The levels of TAAR1 and EAAT2 transcriptions were detected by reverse transcription PCR and their protein levels were analyzed by Western blotting. After TAAR1 plasmid and TAAR1 siRNA were separately transfected into the primary astrocytes pretreated by DA, Western blotting was performed to determine the level of EAAT2 and Amplex Red glutamic acid assay kit was used to analyze Glu uptake in primary cultured astrocyte supernatants. Results The expression of EAAT2 in the primary cultured astrocytes significantly decreased in response to DA, and the level of TAAR1 increased. DA significantly enhanced the Glu uptake in primary cultured astrocyte supernatants. After TAAR1 siRNA transfection, EAAT2 expression was upregulated by DA treatment and Glu content in the supernatants was downregulated. On the contrary, after TAAR1 plasmid transfection, EAAT2 expression descended and Glu level ascended in the supernatants. Conclusion DA reduces the Glu-uptake ability of astrocytes through TAAR1-EAAT2 signaling pathway, causes extracellular Glu accumulation, and ultimately destroys the function of astrocytes.

Insulin Resistance Disrupts the Interaction Between AKT and the NMDA Receptor and the Inactivation of the CaMKIV/CREB Pathway in Minimal Hepatic Encephalopathy.

Hepatic cirrhosis-induced Minimal hepatic encephalopathy (MHE) has been characterized for cognitive dysfunction and central nervous system (CNS) insulin resistance (IR) has been acknowledged to be closely correlated with cognitive impairment while hepatic cirrhosis has been recognized to induce IR. Thus, this study aimed to investigate whether CNS IR occurred in MHE and induced MHE, as well as the underlying mechanism. We found IR in the MHE rats, an especially decreased level of the insulin receptor (InsR), and an increased serine phosphorylation of IRS1 in CNS. PI3K/AKT pathway signaling to the phosphorylation of N-Methyl-d-Aspartate receptors (NMDA receptors, NRs, NR1/NR2B) and downstream activation of the CaMKIV/CREB pathway and final production of neurotrophic factors were triggered by insulin, but impaired in the MHE rats. Additionally, CNS IR, memory impairment, the desensitization of the PI3K/AKT/NMDA receptor (NR)/CaMKIV/CREB pathway and decreased production of BDNF/NT3 in MHE rats were improved by rosiglitazone (RSG). These results suggested that IR, which induces the deficits in the insulin-mediated PI3K/AKT/NR/CaMKIV/CREB/neurotrophin pathway and subsequent memory decline, contributes to the pathogenesis of MHE.

The Multiple Roles of XBP1 in Regulation of Glucose and Lipid Metabolism.

X-box binding protein1 (XBP1) especially exerts its fundamental effects in the cellular organelle endoplasmic reticulum (ER) via affecting three trans-membrane stress sensor proteins: PKRlike ER kinase (PERK), inositol-requiring enzyme 1(IRE1) and activating transcription factor 6(ATF6). At the center of XBP1's broad effects is its remarkable metabolic housekeeper function. XBP1 decreased glucose dysfunction via funneling its effects on improving insulin sensitivity and stimulating insulin secretion. However, XBP1 also yields its double-edged effects, driving the transformation from excess glucose to lipid, which is a key contribution to obesity and T2DM. In this review, we highlight the vital mechanism of XBP1 in manipulating glucose and lipid metabolism involved by multiple signaling pathways.

The Involvement of the Decrease of Astrocytic Wnt5a in the Cognitive Decline in Minimal Hepatic Encephalopathy.

Wnt signaling plays a key role in neuroprotection and synaptic plasticity. We speculate that the impairment of Wnt signaling may mediate astrocytic neurotrophins (NTs) production and the impairment of Wnt signaling to astrocytic NTs production contributes to the pathogenesis of minimal hepatic encephalopathy (MHE). Here, we found that induction of astrocytic NTs synthesis was by Wnt5a via the calcium/calmodulin-sensitive protein kinase II (CaMK II)-cAMP-response element-binding protein (CREB) pathway in PCAs. The decrease of spatial learning and memory and downregulation of astrocytic BDNF and NT-3 were reversed by Wnt5a in MHE rat model. The increased association between CaMK II and CREB followed by phosphorylation of CREB in response to Wnt5a stimulation was suppressed in the MHE rat model. Our results highlight a novel pathogenesis of the contribution of downregulation of NTs to the inhibition of the interaction between Wnt5a and Frizzled-2 in astrocytes in MHE.

Interleukin-4 Ameliorates the Functional Recovery of Intracerebral Hemorrhage Through the Alternative Activation of Microglia/Macrophage.

Neuro-inflammation plays an important role in the recovery of brain injury after stroke. Microglia/macrophage is the major executor in the neuro-inflammation, which can be polarized into two distinct phenotypes: injurious/toxic classical activation (M1 phenotype) and protective alternative activation (M2 phenotype). Here, we investigated whether intracerebral administration of interleukin-4 (IL-4) at an early stage could affect the activation of microglia/macrophage and the corresponding outcome after intracerebral hemorrhage (ICH). The neuro-behavior was recorded between different groups in the rat ICH model. The M1 and M2 markers were then determined by qRT-PCR, western blotting, ELISA, and immunofluorescence, respectively. We observed aberrant activation of microglia/macrophage after ICH. After intracerebral injection of IL-4, M1 activation was greatly inhibited while M2 activation was enhanced, along with improving neurobehavioral recovery from deficits after ICH. Our study showed that early intracerebral injection of IL-4 potentially promotes neuro-functional recovery, probably through enhancing the alternative activation of microglia/macrophage.

Dopamine Burden Triggers Neurodegeneration via Production and Release of TNF-α from Astrocytes in Minimal Hepatic Encephalopathy.

Dopamine (DA)-induced learning and memory impairment is well documented in minimal hepatic encephalopathy (MHE), but the contribution of DA to neurodegeneration and the involved underlying mechanisms are not fully understood. In this study, the effect of DA on neuronal apoptosis was initially detected. The results showed that MHE/DA (10 µg)-treated rats displayed neuronal apoptosis. However, we found that DA (10 µM) treatment did not induce evident apoptosis in primary cultured neurons (PCNs) but did produce TNF-α in primary cultured astrocytes (PCAs). Furthermore, co-cultures between PCAs and PCNs exposed to DA exhibited increased astrocytic TNF-α levels and neuronal apoptosis compared with co-cultures exposed to the vehicle, indicating the attribution of the neuronal apoptosis to astrocytic TNF-α. We also demonstrated that DA enhanced TNF-α production from astrocytes by activation of the TLR4/MyD88/NF-κB pathway, and secreted astrocytic TNF-α-potentiated neuronal apoptosis through inactivation of the PI3K/Akt/mTOR pathway. Overall, the findings from this study suggest that DA stimulates substantial production and secretion of astrocytic TNF-α, consequently and indirectly triggering progressive neurodegeneration, resulting in cognitive decline and memory loss in MHE.

The inactivation of JAK2/STAT3 signaling and desensitization of M1 mAChR in minimal hepatic encephalopathy (MHE) and the protection of naringin against MHE.

BACKGROUND: We previously reported that elevation of intracranial dopamine (DA) levels from cirrhotic livers is implicated in the pathogenesis of minimal hepatic encephalopathy (MHE). Intracellular events in neurons, which lead to memory loss in MHE by elevated DA, however, remain elusive. METHODS: In our present study, an MHE rat model, a DA - intracerebroventricularly (i.c.v.) injected rat model and DA-treated primary cortical neurons (PCNs) were used to study this issue using behavioral tests, double-labeled fluorescent staining, immunoblotting, and semi-quantitative RT-PCR. RESULTS: Cognitive impairment was observed in MHE rats and DA (10 µg, i.c.v.)-treated rats. The levels of DA in the cerebral cortex of both MHE and DA (10 µg)-treated rats were increased. DA conversely modulated the p-JAK2/p-STAT3 levels in PCNs. In accordance, DA downregulated an anacetylcholine-producing enzyme, choline acetyltransferase (ChAT), and desensitized the M1-type muscarinic acetylcholine receptor (M1 mAChR). Furthermore, naringin completely restored cognitive function in MHE/DA (10 µg)-treated models by activating the JAK2/STAT3 axis, paralleling the upregulation of ChAT and sensitization of M1 mAChR. CONCLUSIONS: We propose a hypothesis accounting for memory impairment related to MHE: DA-dependent inactivation of the JAK2/STAT3 axis causes memory loss through cholinergic dysfunction. Our findings provide not only a novel pathological hallmark in MHE but also a novel target in MHE therapy.