gw9662 and Brain-Ischemia

Neuroinflammation plays an important role in the pathophysiological process of acute cerebral infarction, which may aggravate brain injury and hinder neuro-repair. Microglia are innate immune cells in the brain. Ginkgetin has anti-inflammatory and neuroprotective effects, but the mechanism remains unclear. This study aims to explore the regulatory effects of ginkgetin on microglia polarization in brain ischemia. Oxygen glucose deprivation (OGD) cellular model and middle cerebral artery occlusion (MCAO) animal model was used in this study. We first observed the dynamic process of microglia polarization in ischemic stroke, and then investigated the effect of ginkgetin treatment on microglia polarization. Finally, we studied the role of PPARγ signaling pathway and the blocking effect of PPARγ antagonist GW9662 in this process. OGD and cerebral ischemia polarized microglia mainly to M1 type. However, ginkgetin treatment converted microglia from M1 type to M2 type, inhibited neuroinflammation, and exerted neuronal protective effects. PPARγ signaling pathway was activated during this process. The above effects could be blocked by GW9662. Ginkgetin can promote M2 polarization of microglia through PPARγ signaling pathway, thereby inhibiting neuroinflammation and promoting recovery of neurological functions in ischemic stroke.

Topics: Anilides; Animals; Biflavonoids; Brain Ischemia; Infarction, Middle Cerebral Artery; Ischemic Stroke; Microglia; Neuroprotection; PPAR gamma; Stroke

It is known that cerebral ischemia can cause brain inflammation and adiposome can serve as a depot of inflammatory mediators. In the study, the pro-inflammatory and pro-death role of adiposome in ischemic microglia and ischemic brain was newly investigated. The contribution of PPARγ to adiposome formation was also evaluated for the first time in ischemic microglia. Focal cerebral ischemia/reperfusion (I/R) animal model and the in vitro glucose-oxygen-serum deprivation (GOSD) cell model were both applied in the study. GOSD- or I/R-induced adiposome formation, inflammatory activity, cell death of microglia, and brain infarction were, respectively, determined, in the absence or presence of NS-398 (adiposome inhibitor) or GW9662 (PPARγ antagonist). GOSD-increased adiposome formation played a critical role in stimulating the inflammatory activity (production of TNF-α and IL-1β) and cell death of microglia. Similar results were also found in ischemic brain tissues. GOSD-induced PPARγ partially contributed to the increase of adiposomes and adiposome-mediated inflammatory responses of microglia. Blockade of adiposome formation with NS-398 or GW9662 significantly reduced not only the inflammatory activity and death rate of GOSD-treated microglia but also the brain infarct volume and motor function deficit of ischemic rats. The pathological role of microglia-derived adiposome in cerebral ischemia has been confirmed and attributed to its pro-inflammatory and/or pro-death effect upon ischemic brain cells and tissues. Adiposome and its upstream regulator PPARγ were therefore as potential targets for the treatment of ischemic stroke. Therapeutic values of NS-398 and GW9662 have been suggested.

Topics: Anilides; Animals; Animals, Newborn; Brain Ischemia; Cell Death; Culture Media, Serum-Free; Cyclooxygenase 2; Down-Regulation; Glucose; Inflammation; Interleukin-1beta; Lipid Droplets; Male; Microglia; Motor Activity; Neurons; Nitrobenzenes; Oxygen; PPAR gamma; Rats, Sprague-Dawley; Reperfusion Injury; Stroke; Sulfonamides; Tumor Necrosis Factor-alpha

The enzyme 12/15-lipoxygenase (LOX) oxidizes various free fatty acids, including arachidonic acid (AA). In the brain, the principal 12/15-LOX metabolites of AA are 12(S)-HETE and 15(S)-HETE. PPARγ is a nuclear receptor whose activation is neuroprotective through its anti-inflammatory properties. In this study, we investigate the involvement of 12(S)- and 15(S)-HETE in the regulation of PPARγ following cerebral ischemia and their effects on ischemia-induced inflammatory response. We show here the increased expression of 12/15-LOX, predominantly in neurons, and elevated production of 12(S)-HETE and 15(S)-HETE in ischemic brain. The exogenous 12(S)- and 15(S)-HETE increase PPARγ protein level, nuclear translocation, and DNA-binding activity in ischemic rats, suggesting the activation of PPARγ. This effect was further confirmed by showing the increased PPARγ transcriptional activity in primary cortical neurons when incubated with 12(S)- or 15(S)-HETE. Moreover, both 12(S)- and 15(S)-HETE potently inhibited the induction of nuclear factor-κB, inducible NO synthase, and cyclooxygenase-2 in ischemic rats, and elicited neuroprotection. The reversal of the effects of 12(S)- and 15(S)-HETE on pro-inflammatory factors by PPARγ antagonist GW9662 indicated their actions were mediated via PPARγ. Thus, the induction of 12(S)- and 15(S)-HETE during brain ischemia suggests that endogenous signals of neuroprotection may be generated.

Topics: 12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; Active Transport, Cell Nucleus; Anilides; Animals; Arachidonate 12-Lipoxygenase; Arachidonate 15-Lipoxygenase; Arachidonic Acid; Brain Ischemia; Cell Nucleus; Enzyme Activation; Hydroxyeicosatetraenoic Acids; Male; Neurons; PPAR gamma; Rats; Rats, Sprague-Dawley

High mobility group box 1 (HMGB1) elevation after cerebral ischemia activates inflammatory pathways via receptors such as the receptor for advanced glycation end products (RAGE) and toll-like receptors (TLRs) and leads to brain damage. Eicosapentaenoic acid (EPA), a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, attenuates postischemic inflammation and brain damage in male animals. However, postischemic HMGB1 signaling and the effects of EPA on ovariectomized (OVX(+)) rats remain unclear. We hypothesized that EPA attenuates brain damage in OVX(+) rats via the inhibition of HMGB1 signaling in a PPARγ-dependent manner. Seven-week-old female Sprague-Dawley rats were divided into 3 groups; nonovariectomized (OVX(-)) rats and EPA-treated and EPA-untreated OVX(+) rats before cerebral ischemia induction. Another set of EPA-treated OVX(+) rats was injected with the PPARγ inhibitor GW9662. OVX(+) decreased the messenger RNA level of PPARγ and increased that of HMGB1, RAGE, TLR9, and tumor necrosis factor alpha (TNFα) in parallel with ischemic brain damage. EPA restored the PPARγ expression, downregulated the HMGB1 signal-related molecules, and attenuated the ischemic brain damage. Neither OVX(+) nor EPA affected the expression of TLR2 or TLR4. Interestingly, GW9662 partially abrogated the EPA-induced neuroprotection and the downregulation of RAGE and TLR9. In contrast, GW9662 did not affect HMGB1 or TNFα. These results suggest that EPA exerts PPARγ-dependent and PPARγ-independent effects on postischemic HMGB1/TLR9 pathway. The cortical infarct volume exacerbated by OVX(+) is associated with the upregulation of the HMGB1/TLR9 pathway. Suppression of this pathway may help to limit ischemic brain damage in postmenopausal women.

Topics: Anilides; Animals; Brain; Brain Ischemia; Eicosapentaenoic Acid; Female; HMGB1 Protein; Ovariectomy; PPAR gamma; Rats; Rats, Sprague-Dawley; Signal Transduction; Toll-Like Receptor 9; Up-Regulation

Telmisartan, an angiotensin type 1 receptor blocker, is used in the management of hypertension to control blood pressure. In addition, telmisartan has a partial agonistic effect on peroxisome proliferator activated receptor γ (PPARγ). Recently, the effects of telmisartan on spatial memory or the inflammatory response were monitored in a mouse model of Alzheimer's disease (AD). However, to date, no studies have investigated the ameliorative effects of telmisartan on impaired spatial memory and the inflammatory response in an AD animal model incorporating additional cerebrovascular disease factors. In this study, we examined the effect of telmisartan on spatial memory impairment and the inflammatory response in a rat model of AD incorporating additional cerebrovascular disease factors. Rats were subjected to cerebral ischemia and an intracerebroventricular injection of oligomeric or aggregated amyloid-β (Aβ). Oral administration of telmisartan (0.3, 1, 3 mg/kg/d) seven days after ischemia and Aβ treatment resulted in better performance in the eight arm radial maze task in a dose-dependent manner. Telmisartan also reduced tumor necrosis factor α mRNA expression in the hippocampal region of rats with impaired spatial memory. These effects of telmisartan were antagonized by GW9662, an antagonist of PPARγ. These results suggest that telmisartan has ameliorative effects on the impairment of spatial memory in a rat model of AD incorporating additional cerebrovascular disease factors via its anti-inflammatory effect.

Topics: Alzheimer Disease; Amyloid; Angiotensin II Type 1 Receptor Blockers; Anilides; Animals; Anti-Inflammatory Agents; Benzimidazoles; Benzoates; Brain Ischemia; Cerebrovascular Disorders; Cerebrum; Disease Models, Animal; Dose-Response Relationship, Drug; Hippocampus; Inflammation; Male; Maze Learning; Memory; Memory Disorders; PPAR gamma; Rats; Rats, Wistar; Telmisartan; Tumor Necrosis Factor-alpha

Telmisartan, an angiotensin type 1 receptor blocker (ARB), is used for hypertension to control blood pressure and has been shown to have a partial agonistic effect on peroxisome proliferator-activated receptor gamma (PPARgamma). Recently, the ligand of PPARgamma has been implicated in cerebroprotection due to its anti-inflammatory effect. In this study, we investigated whether telmisartan has a cerebroprotective effect on memory impairment and neuronal cell death induced by repeated cerebral ischemia. Repeated cerebral ischemia (RI: 10 min x 2) significantly induced impairment of spatial memory and hippocampal apoptosis in rats. Fourteen-day pre- and post-ischemic administration of telmisartan (0.3, 1, 3mg/kg/day, p.o.) increased the number of correct choices and reduced the number of errors made in the eight-arm radial maze task in a dose-dependent manner in RI treated rats. TUNEL-positive cells in the hippocampus CA1 areas were also reduced following 14-day administration of telmisartan (3mg/kg/day, p.o.). Seven-day post-ischemic administration of telmisartan improved spatial memory and reduced TUNEL-positive cells while 7-day pre-ischemic administration of telmisartan did not. These effects of telmisartan were inhibited by the PPARgamma antagonist, GW9662. On further experiment, 7-day post-ischemic administration of telmisartan reduced the expression of caspase-3 in the hippocampus, and this effect was also inhibited by GW9662. These results suggest that telmisartan improves memory impairment and reduces neuronal apoptosis via a PPARgamma-dependent caspase-3 inhibiting mechanism. Telmisartan, which has the unique character of having both ARB and PPARgamma agonistic effect, will be useful for preventing memory impairment after cerebrovascular disease.

Topics: Analysis of Variance; Anilides; Animals; Apoptosis; Benzimidazoles; Benzoates; Brain Ischemia; Caspase 3; Dose-Response Relationship, Drug; Hippocampus; In Situ Nick-End Labeling; Male; Maze Learning; Memory Disorders; PPAR gamma; Rats; Rats, Wistar; Spatial Behavior; Telmisartan; Time Factors

We have previously reported that prostaglandin A(1) (PGA(1)) reduces infarct size in rodent models of focal ischemia. This study seeks to elucidate the possible molecular mechanisms underlying PGA(1)'s neuroprotective effects against ischemic injury. Rats were subjected to permanent middle cerebral artery occlusion (pMCAO) by intraluminal suture blockade. PGA(1) was injected intracerebroventricularly (icv) immediately after ischemic onset. Western blot analysis was employed to determine alterations in IkappaBalpha, pIKKalpha, and peroxisome proliferator-activated receptor-gamma (PPAR-gamma). Immunohistochemistry was used to confirm the nuclear translocation of nuclear factor-kappaB (NF-kappaB) p65 and the expression of PPAR-gamma. RT-PCR was used to detect levels of c-Myc mRNA. The contribution of PPAR-gamma to PGA(1)'s neuroprotection was evaluated by pretreatment with the PPAR-gamma irreversible antagonist GW9662. A brief increase in pIKKalpha levels and rapid reduction in IkappaBalpha were observed after ischemia. PGA(1) blocked ischemia-induced increases in pIKKalpha levels and reversed the decline in IkappaBalpha levels. Ischemia-induced nuclear translocation of NF-kappaB p65 was attenuated by PGA(1). PGA(1) also repressed the ischemia-induced increase in expression of NF-kappaB target gene c-Myc mRNA. Immunohistochemistry demonstrated an increase in PPAR-gamma immunoreactivity in the nucleus of striatal cells at 3 hr after pMCAO. Western blot analysis revealed that the expression of PPAR-gamma protein significantly increased at 12 hr and peaked at 24 hr. PGA(1) enhanced the ischemia-triggered induction of PPAR-gamma protein. Pretreatment with the irreversible PPAR-gamma antagonist GW9662 attenuated PGA(1)'s neuroprotection against ischemia. These findings suggest that PGA(1)-mediated neuroprotective effect against ischemia appears to be associated with blocking NF-kappaB activation and likely with up-regulating PPAR-gamma expression.

Topics: Active Transport, Cell Nucleus; Anilides; Animals; Brain Infarction; Brain Ischemia; Corpus Striatum; Cytoprotection; Disease Models, Animal; I-kappa B Proteins; Infarction, Middle Cerebral Artery; Male; Nerve Degeneration; Neuroprotective Agents; NF-kappa B; PPAR gamma; Prostaglandins A; Proto-Oncogene Proteins c-myc; Rats; Rats, Sprague-Dawley; RNA, Messenger; Transcription Factor RelA; Up-Regulation

Peroxisome proliferator-activated receptor gamma (PPAR-gamma) is a nuclear membrane-associated transcription factor that governs the expression of various inflammatory genes. PPAR-gamma agonists protect peripheral organs from ischemic injury. In the present study, we investigated whether the PPAR-gamma agonist rosiglitazone is neuroprotective against focal ischemic brain injury. C57/B6 mice underwent 1.5-h middle cerebral artery occlusion, and received either vehicle or rosiglitazone treatment of 0.75, 1.5, 3, 6 or 12 mg/kg (n = 9 per group). Cerebral infarct volume, neurological function, expression of pro-inflammatory proteins and neutrophil accumulation were assessed after ischemia and reperfusion. At 48 h after ischemia, infarct volume was significantly decreased with 3-12 mg/kg of rosiglitazone, with a time window of efficacy of 2 h after ischemia at the optimal dose (6 mg/kg). Neutrophil accumulation was significantly decreased in the brain parenchyma of rosiglitazone-treated mice. Ischemia-induced expression of several inflammatory cytokines and chemokines was markedly reduced in rosiglitazone-treated brains, as determined using proteomic-array analysis. Rosiglitazone treatment improved neurological function at 7 days after ischemia. Moreover, in cultured cortical primary microglia, rosiglitazone attenuated inflammatory responses by decreasing lipopolysaccharide-induced release of tumor necrosis factor-alpha, interleukin (IL)-1beta and IL-6. These results suggest that the PPAR-gamma agonist rosiglitazone has neuroprotective properties that are at least partially mediated via anti-inflammatory actions, and is thus a potential novel therapeutic agent for stroke.

Topics: Anilides; Animals; Animals, Newborn; Behavior, Animal; Blood Pressure; Body Temperature; Brain Ischemia; Cells, Cultured; Cerebral Infarction; Cytokines; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Interactions; Gene Expression; Gene Expression Regulation; Granulocyte Colony-Stimulating Factor; Immunohistochemistry; Infarction, Middle Cerebral Artery; Intercellular Adhesion Molecule-1; Interleukin-3; Lectins; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Microglia; Neuroprotective Agents; Peroxidase; PPAR gamma; Psychomotor Performance; Recombinant Fusion Proteins; Recombinant Proteins; Reperfusion; Rosiglitazone; Thiazolidinediones