Chih-Cheng Wu

Protective effects of rutin on liver injury induced by biliary obstruction in rats.

Rutin has been shown to possess beneficial health effects, including hepatoprotection. However, to date, it has not been demonstrated to have a hepatoprotective effect against cholestatic liver injury. This is the first report to show a protective effect of rutin on cholestatic liver injury. Cholestasis was produced by bile duct ligation (BDL) in male Sprague-Dawley rats for 3 weeks. Daily oral administration of rutin was started 1 week before injury and was maintained for 4 weeks. In comparison with the control group, the BDL group showed liver injury as evidenced by histological changes and elevation in serum biochemicals, ductular reaction, fibrosis, inflammation, and oxidative stress. These pathophysiological changes were attenuated by rutin supplementation. Rutin alleviated BDL-induced transforming growth factor β1 (TGF-β1), interleukin-1β, connective tissue growth factor, and collagen expression. The antifibrotic effect of rutin was accompanied by reductions in α-smooth muscle actin-positive matrix-producing cells and Smad2/3 activity critical to the fibrogenic potential of TGF-β1. Rutin attenuated BDL-induced oxidative stress, leukocyte accumulation, NF-κB activation, and proinflammatory cytokine production. Further studies demonstrated an inhibitory effect of rutin on the redox-sensitive intracellular signaling molecule extracellular signal-regulated kinase (ERK). Rutin also attenuated BDL-induced reduction in NF-E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and AMP-activated protein kinase (AMPK). Taken together, the beneficial effects of rutin were shown to be associated with antioxidative and anti-inflammatory effects as well as the downregulation of NF-κB and TGF-β/Smad signaling, probably via interference of ERK activation and/or enhancement of Nrf2, HO-1, and AMPK activity.

Disruption of in vitro endothelial barrier integrity by Japanese encephalitis virus‐Infected astrocytes

Blood–brain barrier (BBB) characteristics are induced and maintained by crosstalk between brain microvascular endothelial cells and neighboring cells. Using in vitro cell models, we previously found that a bystander effect was a cause for Japanese encephalitis‐associated endothelial barrier disruption. Brain astrocytes, which neighbor BBB endothelial cells, play roles in the maintenance of BBB integrity. By extending the scope of relevant studies, a potential mechanism has been shown that the activation of neighboring astrocytes could be a cause of disruption of endothelial barrier integrity during the course of Japanese encephalitis viral (JEV) infection. JEV‐infected astrocytes were found to release biologically active molecules that activated ubiquitin proteasome, degraded zonula occludens‐1 (ZO‐1) and claudin‐5, and disrupted endothelial barrier integrity in cultured brain microvascular endothelial cells. JEV infection caused astrocytes to release vascular endothelial growth factor (VEGF), interleukin‐6 (IL‐6), and matrix metalloproteinases (MMP‐2/MMP‐9). Our data demonstrated that VEGF and IL‐6 released by JEV‐infected astrocytes were critical for the proteasomal degradation of ZO‐1 and the accompanying disruption of endothelial barrier integrity through the activation of Janus kinase‐2 (Jak2)/signal transducer and activator of transcription‐3 (STAT3) signaling as well as the induction of ubiquitin–protein ligase E3 component, n‐recognin‐1 (Ubr 1) in endothelial cells. MMP‐induced endothelial barrier disruption was accompanied by MMP‐mediated proteolytic degradation of claudin‐5 and ubiquitin proteasome‐mediated degradation of ZO‐1 via extracellular VEGF release. Collectively, these data suggest that JEV infection could activate astrocytes and cause release of VEGF, IL‐6, and MMP‐2/MMP‐9, thereby contributing, in a concerted action, to the induction of Japanese encephalitis‐associated BBB breakdown. GLIA 2015;63:1915–1932

Prenatal buprenorphine exposure decreases neurogenesis in rats.

Perinatal opioid exposure has a negative effect on neurogenesis and produces neurological consequences. However, its mechanisms of action are incompletely understood. Buprenorphine, a mixed opioid agonist/antagonist, is an alternative medication for managing pregnant opioid addicts. This study provides evidence of decreased neurogenesis and depression-like consequences following prenatal exposure to buprenorphine and sheds light on mechanisms of action in a rat model involving administration of intraperitoneal injection to pregnant rats starting from gestation day 7 and lasting for 14 days and a cultured neurosphere model. Results of forced swimming test and tail suspension test showed that pups at postnatal day 21 had worse parameters of depression-like neurobehaviors, independent of gender. Neurobehavioral changes were accompanied by reduction of neuronal composition, biochemical parameters of neural stem/progenitor cells, brain-derived neurotrophic factor (BDNF) expression, tropomyosin-related kinase receptor type B phosphorylation, protein kinase A (PKA) activity, and cAMP response element-binding protein phosphorylation. Results of parallel cell studies further demonstrated a negative impact of buprenorphine on cultured neurospheres, including proliferation, differentiation, BDNF expression and signaling, and PKA activity. Taken together, our results suggest that prenatal exposure to buprenorphine might result in depression-like phenotypes associated with impaired BDNF action and decreased neurogenesis in the developing brain of weanlings.

Autophagy contributes to gefitinib-induced glioma cell growth inhibition.

Epidermal growth factor receptor tyrosine kinase inhibitors, including gefitinib, have been evaluated in patients with malignant gliomas. However, the molecular mechanisms involved in gefitinib-mediated anticancer effects against glioma are incompletely understood. In the present study, the cytostatic potential of gefitinib was demonstrated by the inhibition of glioma cell growth, long-term clonogenic survival, and xenograft tumor growth. The cytostatic consequences were accompanied by autophagy, as evidenced by monodansylcadaverine staining of acidic vesicle formation, conversion of microtubule-associated protein-1 light chain 3-II (LC3-II), degradation of p62, punctate pattern of GFP-LC3, and conversion of GFP-LC3 to cleaved-GFP. Autophagy inhibitor 3-methyladenosine and chloroquine and genetic silencing of LC3 or Beclin 1 attenuated gefitinib-induced growth inhibition. Gefitinib-induced autophagy was not accompanied by the disruption of the Akt/mammalian target of rapamycin signaling. Instead, the activation of liver kinase-B1/AMP-activated protein kinase (AMPK) signaling correlated well with the induction of autophagy and growth inhibition caused by gefitinib. Silencing of AMPK suppressed gefitinib-induced autophagy and growth inhibition. The crucial role of AMPK activation in inducing glioma autophagy and growth inhibition was further supported by the actions of AMP mimetic AICAR. Gefitinib was shown to be capable of reducing the proliferation of glioma cells, presumably by autophagic mechanisms involving AMPK activation.

Depression-like effect of prenatal buprenorphine exposure in rats.

Studies indicate that perinatal opioid exposure produces a variety of short- and long-term neurobehavioral consequences. However, the precise modes of action are incompletely understood. Buprenorphine, a mixed agonist/antagonist at the opioid receptors, is currently being used in clinical trials for managing pregnant opioid addicts. This study provides evidence of depression-like consequence following prenatal exposure to supra-therapeutic dose of buprenorphine and sheds light on potential mechanisms of action in a rat model involving administration of intraperitoneal injection to pregnant Sprague-Dawley rats starting from gestation day 7 and lasting for 14 days. Results showed that pups at postnatal day 21 but not the dams had worse parameters of depression-like neurobehaviors using a forced swimming test and tail suspension test, independent of gender. Neurobehavioral changes were accompanied by elevation of oxidative stress, reduction of plasma levels of brain-derived neurotrophic factor (BDNF) and serotonin, and attenuation of tropomyosin-related kinase receptor type B (TrkB) phosphorylation, extracellular signal-regulated kinase (ERK) phosphorylation, protein kinase A activity, cAMP response element-binding protein (CREB) phosphorylation, and CREB DNA-binding activity. Since BDNF/serotonin and CREB signaling could orchestrate a positive feedback loop, our findings suggest that the induction of oxidative stress, reduction of BDNF and serotonin expression, and attenuation of CREB signaling induced by prenatal exposure to supra-therapeutic dose of buprenorphine provide evidence of potential mechanism for the development of depression-like neurobehavior.

Chromium supplementation improved post-stroke brain infarction and hyperglycemia

Hyperglycemia is common after acute stroke and is associated with a worse outcome of stroke. Thus, a better understanding of stress hyperglycemia is helpful to the prevention and therapeutic treatment of stroke. Chromium is an essential nutrient required for optimal insulin activity and normal carbohydrate and lipid metabolism. Beyond its nutritional effects, dietary supplement of chromium causes beneficial outcomes against several diseases, in particular diabetes-associated complications. In this study, we investigated whether post-stroke hyperglycemia involved chromium dynamic mobilization in a rat model of permanent focal cerebral ischemia and whether dietary supplement of chromium improved post-stroke injury and alterations. Stroke rats developed brain infarction, hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance. Post-stroke hyperglycemia was accompanied by elevated secretion of counter-regulatory hormones including glucagon, corticosterone, and norepinephrine, decreased insulin signaling in skeletal muscles, and increased hepatic gluconeogenesis. Correlation studies revealed that counter-regulatory hormone secretion showed a positive correlation with chromium loss and blood glucose increased together with chromium loss. Daily chromium supplementation increased tissue chromium levels, attenuated brain infarction, improved hyperglycemia, and decreased plasma levels of glucagon and corticosterone in stroke rats. Our findings suggest that stroke rats show disturbance of tissue chromium homeostasis with a net loss through urinary excretion and chromium mobilization and loss might be an alternative mechanism responsible for post-stroke hyperglycemia.

Glechoma hederacea extracts attenuate cholestatic liver injury in a bile duct-ligated rat model

ETHNOPHARMACOLOGICAL RELEVANCE In traditional Chinese medicine, Glechoma hederacea is frequently prescribed to patients with cholelithiasis, dropsy, abscess, diabetes, inflammation, and jaundice. Polyphenolic compounds are main bioactive components of Glechoma hederacea. AIM OF THE STUDY This study was aimed to investigate the hepatoprotective potential of hot water extract of Glechoma hederacea against cholestatic liver injury in rats. MATERIALS AND METHODS Cholestatic liver injury was produced by ligating common bile ducts in Sprague-Dawley rats. Saline and hot water extract of Glechoma hederacea were orally administrated using gastric gavages. Liver tissues and bloods were collected and subjected to evaluation using histological, molecular, and biochemical approaches. RESULTS Using a rat model of cholestasis caused by bile duct ligation (BDL), daily oral administration of Glechoma hederacea hot water extracts showed protective effects against cholestatic liver injury, as evidenced by the improvement of serum biochemicals, ductular reaction, oxidative stress, inflammation, and fibrosis. Glechoma hederacea extracts alleviated BDL-induced transforming growth factor beta-1 (TGF-β1), connective tissue growth factor, and collagen expression, and the anti-fibrotic effects were accompanied by reductions in α-smooth muscle actin-positive matrix-producing cells and Smad2/3 activity. Glechoma hederacea extracts attenuated BDL-induced inflammatory cell infiltration/accumulation, NF-κB and AP-1 activation, and inflammatory cytokine production. Further studies demonstrated an inhibitory effect of Glechoma hederacea extracts on the axis of high mobility group box-1 (HMGB1)/toll-like receptor-4 (TLR4) intracellular signaling pathways. CONCLUSIONS The hepatoprotective, anti-oxidative, anti-inflammatory, and anti-fibrotic effects of Glechoma hederacea extracts seem to be multifactorial. The beneficial effects of daily Glechoma hederacea extracts supplementation were associated with anti-oxidative, anti-inflammatory, and anti-fibrotic potential, as well as down-regulation of NF-κB, AP-1, and TGF-β/Smad signaling, probably via interference with the HMGB1/TLR4 axis.

Indomethacin induced glioma apoptosis involving ceramide signals.

Abstract Nonsteroidal anti‐inflammatory drugs (NSAIDs) are increasingly implicated in the prevention and treatment of cancers apart from their known inhibitory effects on eicosanoid production. One of the NSAIDs, indomethacin, in particular shows promising antineoplastic outcome against glioma. To extend such finding, we here studied in human H4 and U87 glioma cells the possible involvement of the ceramide/protein phosphatase 2 A (PP2A)/Akt axis in the indomethacin‐induced apoptosis. We found that the induced apoptosis was accompanied by a series of biochemical events, including intracellular ceramide generation, PP2A activation, Akt dephosphorylation, Mcl‐1 and FLICE inhibiting protein (FLIP) transcriptional downregulation, Bax mitochondrial distribution, and caspase 3 activation. Such events were also duplicated with a cell‐permeable C2‐ceramide and Akt inhibitor LY294002. Pharmacological inhibition of ceramide synthase by fumonisin B1 and PP2A by okadaic acid moderately attenuated indomethacin‐induced Akt dephosphorylation along with the apoptosis. Results suggested that the ceramide/PP2A/Akt axis is involved in the apoptosis and a possible cyclooxygenase‐independent target for indomethacin. Furthermore, apoptosis regulatory proteins such as Mcl‐1 and FLIP are potential downstream effectors of this axis and their downregulation could turn on the apoptotic program. HighlightsIndomethacin induced glioma cell apoptosis.Indomethacin increased intracellular ceramide levels.Ceramide induced glioma cell apoptosis.LY294002 induced glioma cell apoptosis.Ceramide/PP2A/Akt/Mcl‐1, FLIP axis involved in indomethacin‐induced apoptosis.

Treadmill exercise alleviated prenatal buprenorphine exposure-induced depression in rats

ABSTRACT Mounting evidence suggests that physical exercise shows health benefits in a range of diseases, including psychiatric disorders. Perinatal opioid exposure produces neurobehavioral abnormality, which includes depression symptoms, in patients and their offspring following chronic use of buprenorphine, a mixed agonist/antagonist with a high affinity to opioid receptors, for pain control. Previously, we demonstrated that prenatal buprenorphine exposure in pregnant Sprague‐Dawley rats starting from gestation day 7 and lasting for 14 days caused the development of depression‐like phenotypes in pups at postnatal day 21. Using the same prenatal buprenorphine exposure model, we further demonstrated that a 4‐week course of moderate treadmill exercise conducted on pups starting from postnatal day 22 improved depression‐like neurobehaviors. Prenatal buprenorphine exposure‐induced neurobehavioral changes were accompanied by reductions of neuronal survival, neural stem cell‐associated genes, plasma level of brain‐derived neurotrophic factor (BDNF) and serotonin, phosphorylated tropomyosin‐related kinase receptor type B (TrkB), phosphorylated extracellular signal‐regulated kinase (ERK), PKA activity, phosphorylated cAMP response element‐binding protein (CREB), and CREB DNA binding activity, as well as elevation of repressor element‐1 silencing transcription factor (REST), oxidative stress, and inflammatory responses. Those changes in parameters of plasma and brain were improved by treadmill exercise. In conclusion, the findings of the current study suggest that a non‐pharmacological option, i.e., moderate treadmill exercise, alleviated the development of depression‐like neurobehaviors by resolving the oxidative and inflammatory burden as well as by enhancing neurochemical and neuroendocrine signaling. HighlightsPrenatal buprenorphine exposure induces depression‐like behavior in weanlings.Treadmill exercise improves depression‐like phenotypes.Treadmill exercise increases expression of neurotrophins and neurotransmitters.Treadmill exercise decreases oxidative stress and inflammation.

Valproic acid sensitizes human glioma cells to gefitinib‐induced autophagy

Autophagy and apoptosis represent important cellular processes involved in cancer cell killing mechanisms. Epidermal growth factor receptor inhibitor gefitinib and valproic acid have been implicated in the treatment of malignancies including glioma involving autophagic and apoptotic mechanisms. Therefore, it is interesting to investigate whether a combination of gefitinib and valproic acid shows better cancer cell killing effect on human glioma cells. We found that a nontoxic concentration of valproic acid sensitized U87 and T98G glioma cells to gefitinib cytotoxicity by inhibiting cell growth and long‐term clonogenic survival. The augmented consequences were accompanied by the formation of autophagic vacuoles, conversion of microtubule‐associated protein‐1 light chain 3‐II (LC3‐II), and degradation of p62. Autophagy inhibitor 3‐methyladenosine and chloroquine and genetic silencing of LC3 but not broad‐spectrum caspase inhibitor attenuated gefitinib/valproic acid‐induced growth inhibition. Gefitinib/valproic acid‐induced autophagy was accompanied by the activation of liver kinase‐B1 (LKB1)/AMP‐activated protein kinase (AMPK)/ULK1. Silencing of AMPK and ULK1 suppressed gefitinib/valproic acid‐induced autophagy and growth inhibition. Mechanistic studies showed that gefitinib/valproic acid increased intracellular reactive oxygen species generation and N‐acetyl cysteine attenuated gefitinib/valproic acid‐caused autophagy and growth inhibition. In addition to demonstrating the autophagic mechanisms of gefitinib/valproic acid, the results of this study further suggest that intracellular oxidative stress and the LKB1/AMPK signaling might be a potential target for the development of therapeutic strategy against glioma.