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Genetic Deletion of Neuronal PPARγ Enhances the Emotional Response to Acute Stress and Exacerbates Anxiety: An Effect Reversed by Rescue of Amygdala PPARγ Function. J Neurosci 2016; 36:12611-12623. [PMID: 27810934 DOI: 10.1523/jneurosci.4127-15.2016] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 10/18/2016] [Accepted: 10/29/2016] [Indexed: 01/01/2023] Open
Abstract
PPARγ is one of the three isoforms of the Peroxisome Proliferator-Activated Receptors (PPARs). PPARγ is activated by thiazolidinediones such as pioglitazone and is targeted to treat insulin resistance. PPARγ is densely expressed in brain areas involved in regulation of motivational and emotional processes. Here, we investigated the role of PPARγ in the brain and explored its role in anxiety and stress responses in mice. The results show that stimulation of PPARγ by pioglitazone did not affect basal anxiety, but fully prevented the anxiogenic effect of acute stress. Using mice with genetic ablation of neuronal PPARγ (PPARγNestinCre), we demonstrated that a lack of receptors, specifically in neurons, exacerbated basal anxiety and enhanced stress sensitivity. The administration of GW9662, a selective PPARγ antagonist, elicited a marked anxiogenic response in PPARγ wild-type (WT), but not in PPARγNestinCre knock-out (KO) mice. Using c-Fos immunohistochemistry, we observed that acute stress exposure resulted in a different pattern of neuronal activation in the amygdala (AMY) and the hippocampus (HIPP) of PPARγNestinCre KO mice compared with WT mice. No differences were found between WT and KO mice in hypothalamic regions responsible for hormonal response to stress or in blood corticosterone levels. Microinjection of pioglitazone into the AMY, but not into the HIPP, abolished the anxiogenic response elicited by acute stress. Results also showed that, in both regions, PPARγ colocalizes with GABAergic cells. These findings demonstrate that neuronal PPARγ is involved the regulation of the stress response and that the AMY is a key substrate for the anxiolytic effect of PPARγ. SIGNIFICANCE STATEMENT Peroxisome Proliferator-Activated Receptor Gamma (PPARγ) is a classical target for antidiabetic therapies with thiazolidinedione compounds. PPARγ agonists such as rosiglitazone and pioglitazone are in clinical use for the treatment of insulin resistance. PPARγ has recently attracted attention for its involvement in the regulation of CNS immune response and functions. Here, we demonstrate that neuronal PPARγ activation prevented the negative emotional effects of stress and exerted anxiolytic actions without influencing hypothalamic-pituitary-adrenal axis function. Conversely, pharmacological blockade or genetic deletion of PPARγ enhanced anxiogenic responses and increased vulnerability to stress. These effects appear to be controlled by PPARγ neuronal-mediated mechanisms in the amygdala.
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Pro-Resolving Lipid Mediators Improve Neuronal Survival and Increase Aβ42 Phagocytosis. Mol Neurobiol 2015; 53:2733-49. [PMID: 26650044 DOI: 10.1007/s12035-015-9544-0] [Citation(s) in RCA: 134] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 11/15/2015] [Indexed: 12/31/2022]
Abstract
Inflammation in the brain is a prominent feature in Alzheimer's disease (AD). Recent studies suggest that chronic inflammation can be a consequence of failure to resolve the inflammation. Resolution of inflammation is mediated by a family of lipid mediators (LMs), and the levels of these specialized pro-resolving mediators (SPMs) are reduced in the hippocampus of those with AD. In the present study, we combined analysis of LMs in the entorhinal cortex (ENT) from AD patients with in vitro analysis of their direct effects on neurons and microglia. We probed ENT, an area affected early in AD pathogenesis, by liquid chromatography-tandem mass spectrometry (LC-MS-MS), and found that the levels of the SPMs maresin 1 (MaR1), protectin D1 (PD1), and resolvin (Rv) D5, were lower in ENT of AD patients as compared to age-matched controls, while levels of the pro-inflammatory prostaglandin D2 (PGD2) were higher in AD. In vitro studies showed that lipoxin A4 (LXA4), MaR1, resolvin D1 (RvD1), and protectin DX (PDX) exerted neuroprotective activity, and that MaR1 and RvD1 down-regulated β-amyloid (Aβ)42-induced inflammation in human microglia. MaR1 exerted a stimulatory effect on microglial uptake of Aβ42. Our findings give further evidence for a disturbance of the resolution pathway in AD, and indicate that stimulating this pathway is a promising treatment strategy for AD.
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Liu Y, Huang Y, Lee S, Bookout AL, Castorena CM, Wu H, Gautron L. PPARγ mRNA in the adult mouse hypothalamus: distribution and regulation in response to dietary challenges. Front Neuroanat 2015; 9:120. [PMID: 26388745 PMCID: PMC4558427 DOI: 10.3389/fnana.2015.00120] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/20/2015] [Indexed: 11/13/2022] Open
Abstract
Peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcription factor that was originally identified as a regulator of peroxisome proliferation and adipocyte differentiation. Emerging evidence suggests that functional PPARγ signaling also occurs within the hypothalamus. However, the exact distribution and identities of PPARγ-expressing hypothalamic cells remains under debate. The present study systematically mapped PPARγ mRNA expression in the adult mouse brain using in situ hybridization histochemistry. PPARγ mRNA was found to be expressed at high levels outside the hypothalamus including the neocortex, the olfactory bulb, the organ of the vasculosum of the lamina terminalis (VOLT), and the subfornical organ. Within the hypothalamus, PPARγ was present at moderate levels in the suprachiasmatic nucleus (SCh) and the ependymal of the 3rd ventricle. In all examined feeding-related hypothalamic nuclei, PPARγ was expressed at very low levels that were close to the limit of detection. Using qPCR techniques, we demonstrated that PPARγ mRNA expression was upregulated in the SCh in response to fasting. Double in situ hybridization further demonstrated that PPARγ was primarily expressed in neurons rather than glia. Collectively, our observations provide a comprehensive map of PPARγ distribution in the intact adult mouse hypothalamus.
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Affiliation(s)
- Yang Liu
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA ; Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China
| | - Ying Huang
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Syann Lee
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Angie L Bookout
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Carlos M Castorena
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
| | - Hua Wu
- Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology Wuhan, China
| | - Laurent Gautron
- Division of Hypothalamic Research, Department of Internal Medicine, University of Texas Southwestern Medical Center Dallas, TX, USA
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Nagamoto-Combs K, Kulas J, Combs CK. A novel cell line from spontaneously immortalized murine microglia. J Neurosci Methods 2014; 233:187-98. [PMID: 24975292 DOI: 10.1016/j.jneumeth.2014.05.021] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 05/14/2014] [Accepted: 05/15/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Purified microglia cultures are useful tools to study microglial behavior in vitro. Microglial cell lines serve as an attractive alternative to primary microglia culture, circumventing the costly and lengthy preparation of the latter. However, immortalization by genetic or pharmacologic manipulations may show altered physiology from primary microglia. NEW METHOD A novel microglial cell line was isolated from a primary glial culture of postnatal murine cerebral cortices. The culture contained a population of spontaneously transformed microglia that continued to divide without genetic or pharmacological manipulations. After several clones were isolated, one particular clone, SIM-A9, was analyzed for its microglial characteristics. RESULTS SIM-A9 cells expressed macrophage/microglia-specific proteins, CD68 and Iba1. SIM-A9 cells were responsive to exogenous inflammatory stimulation with lipopolysaccharide and β-amyloid, triggering tyrosine kinase-based and NFκB signaling cascades as well as TNFα secretion. SIM-A9 cells also exhibited phagocytic uptake of fluorescent labeled β-amyloid and bacterial bioparticles. Furthermore, lipopolysaccharide increased the levels of inducible nitric oxide synthase and cyclooxygenase-2, whereas IL-4 stimulation increased arginase-1 levels demonstrating that SIM-A9 cells are capable of switching their profiles to pro- or anti-inflammatory phenotypes, respectively. COMPARISON WITH EXISTING METHODS The use of SIM-A9 cells avoids expensive and lengthy procedures required for the preparation of primary microglia. Spontaneously immortalized SIM-A9 cells are expected to behave more comparably to primary microglia than virally transformed or pharmacologically induced microglial cell lines. CONCLUSIONS SIM-A9 cells exhibit key characteristics of cultured primary microglia and may serve as a valuable model system for the investigation of microglial behavior in vitro.
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Affiliation(s)
- Kumi Nagamoto-Combs
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, 501 North Columbia Road, Stop 9037, Grand Forks, ND 58202-9037, USA.
| | - Joshua Kulas
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, 504 Hamline Street, Neuroscience Building, Grand Forks, ND 58202, USA.
| | - Colin K Combs
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, 504 Hamline Street, Neuroscience Building, Grand Forks, ND 58202, USA.
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Rosiglitazone regulates anti-inflammation and growth inhibition via PTEN. BIOMED RESEARCH INTERNATIONAL 2014; 2014:787924. [PMID: 24757676 PMCID: PMC3971553 DOI: 10.1155/2014/787924] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 01/18/2014] [Accepted: 02/01/2014] [Indexed: 12/13/2022]
Abstract
Peroxisome proliferator-activated receptor gamma (PPARγ) agonist has anti-inflammatory and anticancer properties. However, the mechanisms by which PPARγ agonist rosiglitazone interferes with inflammation and cancer via phosphatase and tensin homolog-(PTEN)-dependent pathway remain unclear. We found that lower doses (<25 μ M) of rosiglitazone significantly inhibited lipopolysaccharide-(LPS)-induced nitric oxide (NO) release (via inducible nitric oxide synthase, iNOS), prostaglandin E2 (PGE2) production (via cyclooxygenase-2, COX-2), and activation of Akt in RAW 264.7 murine macrophages. However, rosiglitazone did not inhibit the production of reactive oxygen species (ROS). In PTEN knockdown (shPTEN) cells exposed to LPS, rosiglitazone did not inhibit NO release, PGE2 production, and activation of Akt. These cells had elevated basal levels of iNOS, COX-2, and ROS. However, higher doses (25-100 μ M) of rosiglitazone, without LPS stimulation, did not block NO release and PGE2 productions, but they inhibited p38 MAPK phosphorylation and blocked ROS generation in shPTEN cells. In addition, rosiglitazone caused G1 arrest and reduced the number of cells in S + G2/M phase, leading to growth inhibition. These results indicate that the anti-inflammatory property of rosiglitazone is related to regulation of PTEN independent of inhibition on ROS production. However, rosiglitazone affected the dependence of PTEN-deficient cell growth on ROS.
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Carta AR, Pisanu A, Carboni E. Do PPAR-Gamma Agonists Have a Future in Parkinson's Disease Therapy? PARKINSON'S DISEASE 2011; 2011:689181. [PMID: 21603186 PMCID: PMC3096077 DOI: 10.4061/2011/689181] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2010] [Accepted: 01/27/2011] [Indexed: 12/24/2022]
Abstract
Thiazolidinediones (TZDs) are peroxisome proliferator-activated receptor (PPAR)-γ agonists commonly used as insulin-sensitizing drugs for the treatment of type 2 diabetes. In the last decade, PPAR-γ agonists have received increasing attention for their neuroprotective properties displayed in a variety of neurodegenerative diseases, including Parkinson's disease (PD), likely related to the anti-infammatory activity of these compounds. Recent studies indicate that neuroinflammation, specifically reactive microglia, plays important roles in PD pathogenesis. Moreover, after the discovery of infiltrating activated Limphocytes in the substantia nigra (SN) of PD patients, most recent research supports a role of immune-mediated mechanisms in the pathological process leading to chronic neuroinflammation and dopaminergic degeneration. PPAR-γ are highly expressed in cells of both central and peripheral immune systems, playing a pivotal role in microglial activation as well as in monocytes and T cells differentiation, in which they act as key regulators of immune responses. Here, we review preclinical evidences of PPAR-γ-induced neuroprotection in experimental PD models and highlight relative anti-inflammatory mechanisms involving either central or peripheral immunomodulatory activity. Specific targeting of immune functions contributing to neuroinflammation either directly (central) or indirectly (peripheral) may represent a novel therapeutic approach for disease modifying therapies in PD.
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Affiliation(s)
- Anna R. Carta
- Department of Toxicology, University of Cagliari, Via Ospedale 72, 09124 Cagliari, Italy
| | - Augusta Pisanu
- Department of Toxicology, University of Cagliari, Via Ospedale 72, 09124 Cagliari, Italy
| | - Ezio Carboni
- Department of Toxicology, University of Cagliari, Via Ospedale 72, 09124 Cagliari, Italy
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Tufekci KU, Genc S, Genc K. The endotoxin-induced neuroinflammation model of Parkinson's disease. PARKINSON'S DISEASE 2011; 2011:487450. [PMID: 21331154 PMCID: PMC3034925 DOI: 10.4061/2011/487450] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2010] [Revised: 11/18/2010] [Accepted: 12/16/2010] [Indexed: 01/22/2023]
Abstract
Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the progressive loss of dopaminergic (DA) neurons in the substantia nigra. Although the exact cause of the dopaminergic neurodegeneration remains elusive, recent postmortem and experimental studies have revealed an essential role for neuroinflammation that is initiated and driven by activated microglial and infiltrated peripheral immune cells and their neurotoxic products (such as proinflammatory cytokines, reactive oxygen species, and nitric oxide) in the pathogenesis of PD. A bacterial endotoxin-based experimental model of PD has been established, representing a purely inflammation-driven animal model for the induction of nigrostriatal dopaminergic neurodegeneration. This model, by itself or together with genetic and toxin-based animal models, provides an important tool to delineate the precise mechanisms of neuroinflammation-mediated dopaminergic neuron loss. Here, we review the characteristics of this model and the contribution of neuroinflammatory processes, induced by the in vivo administration of bacterial endotoxin, to neurodegeneration. Furthermore, we summarize the recent experimental therapeutic strategies targeting endotoxin-induced neuroinflammation to elicit neuroprotection in the nigrostriatal dopaminergic system. The potential of the endotoxin-based PD model in the development of an early-stage specific diagnostic biomarker is also emphasized.
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Affiliation(s)
- Kemal Ugur Tufekci
- Department of Neuroscience, Health Science Institute, Dokuz Eylul University, Inciralti, 35340 Izmir, Turkey
| | - Sermin Genc
- Department of Neuroscience, Health Science Institute, Dokuz Eylul University, Inciralti, 35340 Izmir, Turkey
| | - Kursad Genc
- Department of Neuroscience, Health Science Institute, Dokuz Eylul University, Inciralti, 35340 Izmir, Turkey
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Zhu M, Flynt L, Ghosh S, Mellema M, Banerjee A, Williams E, Panettieri RA, Shore SA. Anti-inflammatory effects of thiazolidinediones in human airway smooth muscle cells. Am J Respir Cell Mol Biol 2010; 45:111-9. [PMID: 20870897 DOI: 10.1165/rcmb.2009-0445oc] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Airway smooth muscle (ASM) cells have been reported to contribute to the inflammation of asthma. Because the thiazolidinediones (TZDs) exert anti-inflammatory effects, we examined the effects of troglitazone and rosiglitazone on the release of inflammatory moieties from cultured human ASM cells. Troglitazone dose-dependently reduced the IL-1β-induced release of IL-6 and vascular endothelial growth factor, the TNF-α-induced release of eotaxin and regulated on activation, normal T expressed and secreted (RANTES), and the IL-4-induced release of eotaxin. Rosiglitazone also inhibited the TNF-α-stimulated release of RANTES. Although TZDs are known to activate peroxisome proliferator-activated receptor-γ (PPARγ), these anti-inflammatory effects were not affected by a specific PPARγ inhibitor (GW 9662) or by the knockdown of PPARγ using short hairpin RNA. Troglitazone and rosiglitazone each caused the activation of adenosine monophosphate-activated protein kinase (AMPK), as detected by Western blotting using a phospho-AMPK antibody. The anti-inflammatory effects of TZDs were largely mimicked by the AMPK activators, 5-amino-4-imidazolecarboxamide ribose (AICAR) and metformin. However, the AMPK inhibitors, Ara A and Compound C, were not effective in preventing the anti-inflammatory effects of troglitazone or rosiglitzone, suggesting that the effects of these TZDs are likely not mediated through the activation of AMPK. These data indicate that TZDs inhibit the release of a variety of inflammatory mediators from human ASM cells, suggesting that they may be useful in the treatment of asthma, and the data also indicate that the effects of TZDs are not mediated by PPARγ or AMPK.
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Affiliation(s)
- Ming Zhu
- Molecular and Integrative Physiological Sciences Program, Department of Environmental Health, Harvard School of Public Health, 665 Huntington Ave., Boston, MA 02115-6021, USA
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Kumari R, Willing LB, Patel SD, Krady JK, Zavadoski WJ, Gibbs EM, Vannucci SJ, Simpson IA. The PPAR-gamma agonist, darglitazone, restores acute inflammatory responses to cerebral hypoxia-ischemia in the diabetic ob/ob mouse. J Cereb Blood Flow Metab 2010; 30:352-60. [PMID: 19861974 PMCID: PMC2949120 DOI: 10.1038/jcbfm.2009.221] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Diabetes is an increased risk factor for stroke and results in increased brain damage in experimental animals and humans. The precise mechanisms are unclear, but our earlier studies in the db/db mice suggested that the cerebral inflammatory response initiating recovery was both delayed and diminished in the diabetic mice compared with the nondiabetic db/+ mice. In this study, we investigated the actions of the peroxisome proliferator-activated receptor (PPAR)-gamma agonist darglitazone in treating diabetes and promoting recovery after a hypoxic-ischemic (H/I) insult in the diabetic ob/ob mouse. Male ob/+ and ob/ob mice received darglitazone (1 mg/kg) for 7 days before induction of H/I. Darglitazone restored euglycemia and normalized elevated corticosterone, triglycerides, and very-low-density lipoprotein levels. Darglitazone dramatically reduced the infarct size in the ob/ob mice at 24 h of recovery compared with the untreated group (30+/-13% to 3.3+/-1.6%, n=6 to 8) but did not show any significant effect in the ob/+ mice. Microglial and astrocytic activation monitored by cytokine expression (interleukin-1beta and tumor necrosis factor-alpha) and in situ hybridization studies (bfl1 and glial fibrillary acidic protein) suggest a biphasic inflammatory response, with darglitazone restoring the compromised proinflammatory response(s) in the diabetic mouse at 4 h but suppressing subsequent inflammatory responses at 8 and 24 h in both control and diabetic mice.
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Affiliation(s)
- Rashmi Kumari
- Department of Neural and Behavioral Sciences, College of Medicine, Hershey Medical Center, Pennsylvania State University, Hershey, Pennsylvania 17033, USA
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