Mitochondrial ATP-Sensitive Potassium Channels Play a Role in Reducing Both Myocardial Infarction and Reperfusion Arrhythmia in Remote Ischemic Preconditioned Hearts.

BACKGROUND: Mitochondrial ATP-sensitive potassium (mKATP) channels play a role in reperfusion arrhythmias (RAs) in ischemia-reperfusion (I/R) injury. Evidence suggests that remote ischemic preconditioning (RIPC) reduces RAs, however not much is known on the mechanistic role of mKATP in RIPC. We evaluated whether mKATP channels are associated with reducing arrhythmia and infarct size in RIPC. METHODS: Isolated rat hearts received 30 minutes of regional ischemia followed by 2 hours of reperfusion through the Langendorff perfusion system. RIPC was induced by 3 cycles of 5 minutes occlusion and 5 minutes release of the bilateral femoral artery. The animals were randomly divided into 4 groups as follows: 1) CON, I/R injury but not RIPC, 2) RIPC, 3) HD+RIPC, pretreatment of the selective mKATP channel blocker, 5-hydroxydecanoate (5-HD), in RIPC, and 4) HD, pretreatment of 5-HD in CON. Cardiodynamics and infarct size were determined. The severity of arrhythmia was quantitated via the Curtis and Walker scoring system as well as the Lepran scoring system. RESULTS: RIPC significantly reduced the infarct size over AR (25.7 ± 2.6%) compared to CON (37.0 ± 2.6%, P < 0.05). The selective mKATP channel blocker 5-HD significantly inhibited the infarct-reducing effect of RIPC (39.3 ± 3.0%, P < 0.05 vs. RIPC). Additionally, RIPC significantly reduced the arrhythmia score compared to CON (14.6 ± 1.9 to 8.7 ± 0.4, P = 0.023, by Curtis and Walker's system, 16.1 ± 2.1 to 9.1 ± 0.5, P = 0.006, by Lepran's system). The anti-arrhythmic effect of RIPC was blocked by 5-HD (15.5 ± 1.6 and 16.0 ± 1.2, by Curtis and Walker's and Lepran's system, respectively). CONCLUSIONS: The selective mKATP channel blocker, 5-HD, inhibited the infarct-limitation and anti-arrhythmic effect of RIPC. The mKATP channels play a role in the reduction of both infarct size and RAs in RIPC.

Palladium-Catalyzed Regioselective Synthesis of 3-Arylindoles from N-Ts-Anilines and Styrenes.

A Pd-catalyzed intermolecular oxidative annulation between N-Ts-anilines and styrenes was developed. This method offers a straightforward and robust approach to a wide range of 3-arylindoles using readily available starting materials with good functional-group tolerance and high regioselectivity and efficiency. Further elaboration of the products obtained from this process provided access to highly functionalized and structurally diverse indoles, for example, 3-(indol-3-yl)carbazoles, 1,9-dihydropyrrolo-[2,3-b]carbazoles, and 3'-aryl-3,5'-biindoles.

Remifentanil postconditioning has cross talk with adenosine receptors in the ischemic-reperfused rat heart.

BACKGROUND: Although there is a possibility of cross talk between opioid and adenosine signaling pathways in the ischemic-reperfused myocardium, it is not clear that an ultra-short-acting opioid receptor agonist remifentanil-induced postconditioning (RPostC) has cross talk with adenosine receptor (ADR). The purpose of this study was to determine whether there is cross talk with ADR in RPostC. MATERIALS AND METHODS: Isolated rat hearts were subjected to 30 min of regional ischemia and 2 h of reperfusion. RPostC was induced by 100 ng/mL of remifentanil perfusion, 5 min before reperfusion, followed by 5 min of reperfusion. The nonspecific opioid receptor antagonist naloxone (NAL) and the nonspecific ADR antagonist 8-(p-sulfophenyl) theophylline hydrate (8-SPT) were perfused for a 20-min period, 10 min before RPostC to the end of RPostC. Western blot analysis was performed to detect phospho-ERK1/2 in cultured cardiomyocytes. RESULTS: In cultured cardiomyocytes, remifentanil incubation significantly increased the phosphorylation of ERK1/2 and this effect was blocked by both NAL and 8-SPT (P < 0.01 and P < 0.05, respectively). RPostC significantly reduced infarct size over ischemic area at risk from 34.1 ± 10.5% to 16.6 ± 7.5% (P < 0.05 versus control). The infarct-limitation effect of RPostC was reversed by both NAL (33.8 ± 13.0%, P < 0.05) and 8-SPT (35.7 ± 14.5%, P < 0.01). CONCLUSIONS: This study strongly implies that the intracellular signaling pathways of cardioprotection by RPostC has cross talk with ADR in the ischemic-reperfused myocardium.

The effect of radiographic contrast media on reperfusion injury in the isolated rat heart.

BACKGROUND AND OBJECTIVES: We investigated the effects of commonly used contrast media (CM) on myocardial ischemia-reperfusion injury in isolated rat hearts. SUBJECTS AND METHODS: Isolated rat hearts were subjected to 30 minutes of regional ischemia and 2 hours of reperfusion. The following CM (1 mL/1 L Krebs-Henseleit buffer) were randomly perfused for 15 minutes beginning 5 minutes before reperfusion and ending 10 minutes after reperfusion: iohexol (n=8), iopromide (n=8), ioversol (n=8), iomeprol (n=8), iopamidol (n=7), ioxaglate (n=8), and iodixanol (n=7). The effects of a direct bolus injection of undiluted iohexol, iopromide, or ioxaglate (each n=6) via the aortic root immediately prior to reperfusion were also evaluated. The area of necrosis, expressed as the percentage of the area at risk (AN/AR), and cardiodynamic variables were measured. RESULTS: The AN/AR of the control and experimental groups in the order described in methods was 33.7±6.4%, 30.3±7.4%, 34.7±12.6%, 29.2±10.2%, 20.9±7.6%, 22.6±8.7%, 18.8±7.9%, and 19.9±11.4%, respectively. Groups that received iomeprol and ioxaglate exhibited significantly decreased AN/AR values compared to those of control hearts (p=0.042 and p=0.013). No significant differences in the AN/AR were observed between control hearts and the groups injected with a single bolus of CM. No significant hemodynamic changes were noted after reperfusion among the groups. CONCLUSION: The overall effects of the CM on coronary reperfusion were not deleterious, and better effects were noted in two CM groups. However, it is unclear whether this result was attributed to a specific physiochemical property of the CM.

Metal-free C-H amination for indole synthesis.

An effective metal-free C-H amination of N-Ts-2-alkenylanilines by using DDQ as an oxidant has been developed to afford a diverse range of substituted indoles. This protocol is operationally simple and robust, obviates the need of expensive transition-metal catalysts, and offers a broad substrate scope. A mechanism involving a radical cation generated by SET and a migratorial process via a phenonium ion intermediate is proposed.

Cardiodynamics and infarct size in regional and global ischemic isolated heart model: comparison of 1 hour and 2 hours reperfusion.

BACKGROUND AND OBJECTIVES: We investigated whether 1 hour reperfusion is enough to assess cardiodynamics and infarct size in both regional ischemia (RI) and global ischemia (GI) in isolated rat heart models. MATERIALS AND METHODS: Hearts were randomly assigned to one of the following groups (each n=14): 1) Sham hearts for 1 hour; 2) Sham hearts for 2 hours; 3) 30 minutes RI followed by 1 hour reperfusion; 4) 30 minutes of RI followed by 2 hours reperfusion; 5) 30 minutes GI followed by 1 hour reperfusion; and 6) 30 minutes GI followed by 2 hours reperfusion. RESULTS: There were no significant differences in infarct size between 1 hour and 2 hours reperfusion in both RI and GI. Left ventricular developed pressure was significantly decreased at both 1 hour and 2 hours reperfusion in groups of RI and GI compared to baseline (p<0.01). Rate-pressure product and +dP/dt(max) also significantly decreased compared to baseline level at both 1 hour and 2 hours reperfusion in groups of RI and GI (p<0.05). CONCLUSION: There was no significant difference in infarct size between 1 hour and 2 hours reperfusion in groups of RI and GI. Cardiodynamic variables measured at 1 hour and 2 hours reperfusion significantly decreased compared to baseline level. Our data suggests that reperfusion of 1 hour is sufficient to assess cardiodynamics in both regional and global ischemic isolated hearts model.

Stromal cell derived factor-1 (SDF-1) targeting reperfusion reduces myocardial infarction in isolated rat hearts.

Recent studies have shown that stromal cell derived factor-1 (SDF-1), first known as a cytokine involved in recruiting stem cells into injured organs, confers myocardial protection in myocardial infarction, which is not dependent on stem cell recruitment but related with modulation of ischemia-reperfusion (I/R) injury. However, the effect of SDF has been studied only in a preischemic exposure model, which is not clinically relevant if SDF is to be used as a therapeutic agent. Our study was aimed at evaluating whether or not SDF-1 confers cardioprotection during the reperfusion period. Hearts from SD rats were isolated and perfused with the Langendorff system. Proximal left coronary artery ligation, reperfusion, and SDF perfusion in KH buffer was done according to study protocol. Area of necrosis (AN) relative to area at risk (AR) was the primary endpoint of the study. Significant reduction of AN/AR by SDF in an almost dose-dependent manner was noted during both the preischemic exposure and reperfusion periods. In particular, infusion of a high concentration of SDF (25 nM/L) resulted in a dramatic reduction of infarct size, which was greater than that achieved with ischemic pre- or postconditioning. SDF perfusion during reperfusion was associated with a similar significant reduction of infarct size as preischemic SDF exposure. Further studies are warranted to assess the potential of SDF as a therapeutic agent for reducing I/R injury in clinical practice.

Morphine and remifentanil-induced cardioprotection: its experimental and clinical outcomes.

During the past few decades, a large number of animal studies demonstrated that commonly used opioids could provide cardioprotection against ischemia-reperfusion (I/R) injury. Opioid-induced preconditioning or postconditioning mimics ischemic preconditioning (I-Pre) or ischemic postconditioning (I-Post). Both δ- and κ-opioid receptors (OPRs) play a crucial role in opioid-induced cardioprotection (OIC). Down stream signaling effectors of OIC include ATP-sensitive potassium (K(ATP)) channels, protein kinase C (PKC), tyrosine kinase, phosphatidylinositol-3-kinase (PI3-kinase), extracellular signal regulated kinase1/2 (ERK1/2), glycogen synthase kinase-3ß (GSK-3ß), and mitochondrial permeability transition pore (MPTP), among others. Recently, various reports also suggest that opioids could provide cardioprotection in humans. This review will discuss OIC using mostly morphine and remifentanil which are widely used during cardiac anesthesia in addition to the clinical implications of OIC.

Morphine-induced postconditioning modulates mitochondrial permeability transition pore opening via delta-1 opioid receptors activation in isolated rat hearts.

BACKGROUND: It is generally accepted that morphine affords cardioprotection against ischemia/reperfusion injury. Inhibition of the mitochondrial permeability transition pore (MPTP) is considered an end target for cardioprotection. The aim of this study was to investigate the involvement of opioid receptors (OR) and MPTP in morphine-induced postconditioning (M-Post). METHODS: Isolated rat hearts were subjected to 30 min of regional ischemia and 2 h of reperfusion. Hearts were treated with 1 µM morphine, with or without the OR antagonists or a MPTP opener at early reperfusion. Infarct size was measured with 2,3,5-triphenyltetrazolium chloride staining. RESULTS: There were no significant differences in cardiodynamic variables except a decrease in heart rate in the M-Post group (P < 0.01 vs. control) after reperfusion. M-Post dramatically reduced infarct-risk volume ratio (9.8 ± 2.5%, P < 0.001 vs. 30.0 ± 3.7% in control). This beneficial effect on infarct volume by M-Post was comparable with ischemic postconditioning (11.9 ± 2.2%, P > 0.05). The nonspecific OR antagonist naloxone (25.7 ± 1.9%, P < 0.01), the δ-OR antagonist naltrindole (27.8 ± 4.3%, P < 0.05) and δ(1)-OR antagonist 7-benzylidenenaltrexone (24.7 ± 3.7%, P < 0.01) totally abrogated the anti-infarct effect of M-Post. In addition, the anti-infarct effect by M-Post was also totally blocked by the MPTP opener atractyloside (26.3 ± 5.2%, P < 0.05). CONCLUSIONS: M-Post effectively reduces myocardial infarction. The anti-infarct effect by M-Post is mediated via activation of δ-OR, especially δ(1)-OR, and inhibition of the MPTP opening.

Kappa-opioid receptor activation during reperfusion limits myocardial infarction via ERK1/2 activation in isolated rat hearts.

BACKGROUND: We investigated whether p42/p44 extracellular signal-regulated kinases (ERK1/2) and/or phosphatidylinositol-3-OH kinase (PI3K)-Akt play a crucial role in cardioprotection by κ-opioid receptor (KOP) activation. METHODS: Langendorff perfused rat hearts were subjected to 30 min of regional ischemia and 2 h of reperfusion. Antagonists of ERK1/2 and PI3K were perfused in hearts treated with the KOP agonist U50488H (U50). Infarct size was measured after 2 h of reperfusion. The phosphorylation states of ERK1/2 and Akt by Western immunoblots were determined. Drugs were perfused for a period of 5 min before and 30 min after reperfusion. RESULTS: Inhibition of ERK1/2 (26.8 ± 2.9%, P < 0.05 vs. U50) but not PI3K (15.5 ± 1.1%, P > 0.05 vs. U50) completely abrogated the anti-infarct effect of U50488H. Western blot analysis revealed a significant increase in ERK1/2 but not Akt phsophorylation in U50488H-treated hearts as compared to control hearts when measured immediately after reperfusion. CONCLUSIONS: KOP activation effectively reduces myocardial infarction. The anti-infarct effect of U50488H is mediated by the ERK1/2, but not the PI3K-Akt pathway.

Effects of postconditioning with N,N,N'N'-tetrakis-[2-pyridylmethyl]-ethylenediamine in isolated rat hearts.

BACKGROUND: It was reported that N,N,N'N'-tetrakis-[2-pyridylmethyl]-ethylenediamine (TPEN), a transition metal chelator, confers cardioprotection against myocardial ischemic injury. In this study, we investigated the effect of TPEN targeting reperfusion period in isolated rat hearts. METHODS: Langendorff perfused rat hearts were subjected to 30 min of regional ischemia and 2 h of reperfusion. Hearts were randomly assigned to either control (n = 9) or 10 microM of TPEN (n = 8) groups. TPEN was perfused for a period of 5 min before and 30 min after reperfusion. RESULTS: The ratio of infarct area/ischemic area (AN/AR) was significantly reduced in TPEN treated hearts (6.9 +/- 1.7%, P < 0.001) compared to control hearts (29.5 +/- 3.2%). Recovery of left ventricular developed pressure (LVDP), rate-pressure product (RPP), +dP/dt(max), and -dP/dt(min) in the control group after reperfusion were 53.8 +/- 6.2%, 51.0 +/- 6.3%, 51.9 +/- 5.7%, and 51.4 +/- 5.7%, respectively, of the baseline levels. In the TPEN group, LVDP, RPP, +dP/dt(max), and -dP/dt(min) returned to 58.5 +/- 4.6%, 54.8 +/- 6.4%, 61.7 +/- 4.9%, and 53.4 +/- 3.9%, respectively, of the baseline levels. There were no significant differences in the cardiodynamic variables between the two groups (P > 0.05). CONCLUSIONS: Pharmacological postconditioning with TPEN reduces myocardial infarction however, TPEN does not modify post-ischemic systolic dysfunction in isolated rat hearts.

Polyphenol (-)-epigallocatechin gallate targeting myocardial reperfusion limits infarct size and improves cardiac function.

BACKGROUND: This experiment was performed to determine the effect of polyphenolic (-)-epigallocatechin (EGCG), the most abundant catechin of green tea, given at reperfusion period. METHODS: Isolated rat hearts were subjected to 30 min of regional ischemia and 2 h of reperfusion. Green tea extract (GT) was perfused with the following concentrations; 0, 0.5, and 1 microM (GT-O, GT-0.5, and GT-1, respectively). In a next experiment, hearts were assigned randomly to one of the following groups; Control, EGCG-1 (1 microM of EGCG), and EGCG-10 (10 microM of EGCG). GT and EGCG were perfused for a period of 5 min before and 30 min after reperfusion. For comparison of cardioprotection among groups, morphometric measurement was performed by 2,3,5-triphenyltetrazolium chloride staning. RESULTS: GT 1 microM (10.3 +/- 2.1%, P < 0.05) significantly reduced infarct volume as a percentage of ischemic volume compared to untreated hearts (27.4 +/- 1.1%). EGCG 10 microM (13.2 +/- 4.0%) significantly reduced myocardial infarction compared to control hearts (27.2 +/- 1.4%, P = 0.002). After 2 h of reperfusion, cardiodynamic variables, including left ventricular developed pressure, rate-pressure produce, +dP/dt(max), and -dP/dt(min) were significantly improved by 10 microM of EGCG compared to control hearts (P = 0.01, 0.016, 0.009, and 0.019, respectively). CONCLUSIONS: EGCG treatment at an early reperfusion period reduces myocardial infarction and improves cardiodynamics in isolated rat hearts.

Cardioprotection by kappa-opioid receptor agonist U50488H is mediated by opioidergic regulation but not by calcium current modulation.

BACKGROUND: Because the kappa-opioid receptor (OR) agonist U50488H stimulates opioidergic regulation and inhibits L-type Ca(2+) channels, this study was aimed at assessing the roles of OR and L-type Ca(2+) channels on U50488H-induced cardioprotection. METHODS: Langendorff-perfused rat hearts were subjected to 30 min of regional ischemia and 2 h of reperfusion. Isolated hearts were treated with U50488H with or without the kappa-OR antagonist nor-binaltorphimine (nor-BNI) or the Ca(2+) channels activator BAY K 8644. Infarct size was measured with 2,3,5-triphenyltetrazolium chloride staining. RESULTS: U50488H treatment at reperfusion: (1) significantly reduced infarct size (11.3 +/- 1.3%) compared to control hearts (27.7 +/- 1.1%, P < 0.001), an effect that was completely blocked by nor-BNI (24.0 +/- 0.9%, P < 0.001 vs. U50488H) but not by BAY K 8644 (7.1 +/- 1.7%, P > 0.05 vs. U50488H); (2) significantly increased left ventricular developed pressure (65.3 +/- 4.8%) after 2 h of reperfusion compared to control hearts (44.8 +/- 3.6%, P < 0.05), an effect that was abrogated by nor-BNI (40.5 +/- 4.5%, P > 0.05 vs. control) but not by BAY K 8644 (64.3 +/- 5.6%, P < 0.01 vs. control); and (3) significantly decreased heart rate (P < 0.01 vs. control), an effect that was completely abrogated by both nor-BNI and BAY K 8644. CONCLUSIONS: U50488H significantly limits myocardial infarction and stunning in isolated rat hearts after ischemia-reperfusion induction. The infarct size limitation and contractility improvement observed with U50488H treatment during reperfusion are entirely mediated by OR stimulation and not by Ca(2+) channel modulation.

Rocuronium bromide induced anaphylaxis in a child -A case report-.

Anaphylaxis or anaphylactoid reaction in pediatric patient during anesthesia is rare. We report a rocuronium induced anaphylactic reaction in a 33-month-old female. The patient was scheduled to undergo escharectomy due to injuries suffered from a major burn. Shortly after administration of rocuronium, the patient developed severe hypotension, tachycardia, and hypoxia. A similar reaction occurred after administration of rocuronium on subsequent anesthesia. She underwent uneventful anesthesia with volatile induction and maintenance of anesthesia with sevoflurane on her next 7 operations without using of muscle relaxant.

False positive immunoglobulin m antibody to cytomegalovirus in child with infectious mononucleosis caused by epstein-barr virus infection.

A 16-month-old boy was admitted because of cough that had lasted for 10 days. The patient showed severe hepatomegaly incidentally, and dual positivity of Immunoglobulin (Ig) M to Epstein-Barr virus (EBV) viral capsid antigen (VCA) and cytomegalovirus (CMV). On the basis of seroconversion to Epstein-Barr nuclear antigen (EBNA) Ig G positivity and reduced CMV Ig M titer with persistently negative CMV Ig G, a definite diagnosis of EBV-induced infectious mononucleosis was established 1 year 2 month later.

Rapid injection of rocuronium reduces withdrawal movement on injection.

STUDY OBJECTIVE: To test whether rapid injection of rocuronium reduces withdrawal movement on injection. DESIGN: Randomized, prospective trial. SETTING: Operating room in a university hospital. PATIENTS: 150 ASA physical status I and II patients aged 18 to 60 years, undergoing general anesthesia. INTERVENTIONS: Patients were randomized to three groups. After undergoing anesthesia induction with thiopental sodium, then 5 seconds later receiving a rubber tourniquet applied to the mid-forearm to stop intravenous (IV) flow by gravity, the pretreatment drug was injected. The tourniquet was held for 15 seconds then released, and 1.0 mg/kg of 1% rocuronium was injected IV. Group C patients (n = 50) were pretreated with 0.1 mL/kg of 0.9% NaCl and then injected with rocuronium slowly within 10 seconds. Group L patients (n = 50) were pretreated with 0.1 mL/kg of preservative-free 1% lidocaine and then injected with rocuronium slowly within 10 seconds. Group R patients (n = 50) were pretreated with 0.1 mL/kg of 0.9% NaCl and then rapidly injected with rocuronium within approximately one second (as quickly as possible). MEASUREMENTS: After injection of the patient with the study drug, a single anesthesiologist with no knowledge of the study protocol graded each patient's response as follows: 0 = no response; 1 = mild movement limited to the wrist only; 2 = moderate movement involving the elbow and shoulder; and 3 = severe movement involving more than one extremity. MAIN RESULTS: Group C had the most intense and frequent withdrawal response. The frequency and intensity of withdrawal movement was significantly less in Groups L and R than Group C. No significant difference in withdrawal response between Groups L and R was noted. CONCLUSIONS: Withdrawal response can be significantly reduced for rocuronium injection without lidocaine pretreatment, simply through rapid injection.

Cardiomyopathy after local infiltration or application of epinephrine for plastic surgery under general anesthesia : Two cases report.

Catecholamine-induced cardiomyopathy rarely occurs after local epinephrine infiltration. We experienced two patients with catecholamine induced cardiomyopathies. An 8-yr-old girl was scheduled for closed reduction of a nasal bone fracture. Propofol and rocuronium bromide were used for induction of anesthesia. After induction, lidocaine mixed with epinephrine was infiltrated to the block of supratrochlear and infraorbital nerves. About 10 sec later ventricular tachycardia, hypotension, hypoxemia, and pulmonary edema developed. The other case was a 23-yr-old woman with a nasal bone fracture. Propofol, rocuronium bromide, and fentanyl were used for the induction of anesthesia. After induction, epinephrine-containing wet gauze was packed in the nasal cavity for mucosal shrinkage. About 1 minute later, hypertension, tachycardia, and hypoxemia developed. After each operation, a transthorcic echo-cardiogram revealed hypokynesia of the myocardium.

Green tea polyphenol (-)-epigallocatechin gallate reduces neuronal cell damage and up-regulation of MMP-9 activity in hippocampal CA1 and CA2 areas following transient global cerebral ischemia.

Previous studies have demonstrated that (-)-epigallocatechin gallate (EGCG), a green tea polyphenol, protects against ischemia and reperfusion-induced injury in many organ systems. Here, we test the hypothesis that part of EGCG's neuroprotective effects may involve a modulation of matrix metalloproteinases (MMPs) after cerebral ischemia. C57BL/6 mice were subjected to 20 min of transient global cerebral ischemia. EGCG (50 mg/kg) or vehicle (saline) was administered i.p. immediately after ischemia. Brains were examined 3 days after ischemia. The effects of EGCG on MMP (gelatinase) activity and neuronal damage in the hippocampus were assessed. Gelatin gel zymography showed induction of active forms of MMP-9 protein after transient global cerebral ischemia. In situ zymography showed that ischemic gelatinase activity occurred primarily in pyramidal neuronal areas after brain ischemia. Mice treated with EGCG showed significantly reduced gelatinase levels. Neuronal damage was evident in CA1 and CA2 pyramidal sectors, corresponding to TUNEL-positive signals. In EGCG-treated mice, delayed neuronal damage was significantly reduced compared with vehicle-treated mice. These results demonstrate that the green tea polyphenol EGCG suppresses MMP-9 activation and reduces the development of delayed neuronal death after transient global cerebral ischemia in mouse brain.

PPARgamma agonist pioglitazone reduces [corrected] neuronal cell damage after transient global cerebral ischemia through matrix metalloproteinase inhibition.

Previous studies have demonstrated that pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, inhibits ischemia-induced injury in various tissues including neural tissue. Pioglitazone has also been shown to reduce matrix metalloproteinase (MMP) activity. Because MMP is known to play a major role in the pathophysiology of brain ischemia, the present study was undertaken to test whether pioglitazone attenuates ischemic neuronal damage through MMP inhibition. C57BL/6 mice were subjected to global brain ischemia for 20 min. Animals were killed 72 h after ischemia. Oral pioglitazone (40 mg/kg/day, as a suspension in 0.5% carboxymethylcellulose) was administered to mice twice daily for 3 days before ischemia and twice daily after ischemia until the animals were killed. We investigated gelatinase activity by zymography and laminin immunohistochemistry. Histological analysis was also performed to test the protective effect of pioglitazone on neuronal damage. Mice treated with pioglitazone had attenuated gelatinase activity. Gelatin gel and in situ zymography showed up-regulation of gelatinase activity after ischemia. Pioglitazone significantly inhibited ischemia-induced elevation of the active form of MMP-9. Pioglitazone also reduced up-regulation of in situ gelatinase activity and laminin breakdown induced by ischemia in the hippocampus. There was marked neuronal damage in the CA1 and CA2 areas after ischemia. Neuronal damage in mice was significantly decreased by pioglitazone treatment, compared with vehicle-treated mice. Pioglitazone also inhibited TdT-mediated dUTP nick end labeling staining in CA1 and CA2 areas. Pioglitazone, a PPARgamma agonist, reduces delayed neuronal damage induced by global ischemia through inhibition of MMP-9 activity.

Protective effect of quercetin, a natural flavonoid against neuronal damage after transient global cerebral ischemia.

Previous studies have demonstrated that quercetin, a bioflavonoid shows the inhibitory effect against ischemia and reperfusion-induced injury in various tissues including neural tissue. Quercetin is also reported to have an inhibitory effect against matrix metalloproteinases (MMPs). Because MMPs are known to play a main role in the pathophysiology of brain ischemic insult, their mechanisms of possible protective effect of quercetin against brain ischemia remain to be clarified. In the present study, C57BL/6 mice were subjected to 20 min transient global brain ischemia. Cerebral blood flow was monitored by laser doppler flowmeter. Animals were sacrificed 72 h after ischemia. Quercetin (50 mg/kg, dissolved in saline) was intraperitoneally administered to mice at 30 min before and immediately after ischemia and from the second day, quercetin was then administered once daily until sacrifice. The present study was undertaken to test the effect of quercetin on neuronal damage after transient cerebral ischemia. Neuronal damages were remarkable in the medial portion of CA1 and CA2 areas after ischemic insult. In quercetin-treated mice, delayed neuronal damage was significantly decreased compared with vehicle-treated mice. Mice treated with quercetin showed attenuated brain MMP-9 activity. Gelatin gel zymography showed an induction of MMP-9 protein after ischemia. Quercetin significantly inhibited ischemia-induced elevation of MMP-9. In situ zymography showed elevations in gelatinase activities after brain ischemia. Quercetin also inhibited TdT-mediated dUTP nick end labeling (TUNEL) staining in CA1 and CA2 areas. These results demonstrate that quercetin, a natural flavonoid reduces global ischemia-induced neuronal damage through inhibition of MMP-9 activity.