scholarly journals BDNF-endocannabinoid interactions at neocortical inhibitory synapses require phospholipase C signaling

2014 ◽  
Vol 111 (5) ◽  
pp. 1008-1015 ◽  
Author(s):  
Liangfang Zhao ◽  
Eric S. Levine
Keyword(s):  
Protein Kinase ◽  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Metabotropic Glutamate Receptor ◽  
Glutamate Release ◽  
Brain Slices ◽  
Receptor Activation ◽  
Inhibitory Synapses ◽  
Trkb Receptor ◽  
Layer 2

Endogenous cannabinoids (endocannabinoids) and neurotrophins, particularly brain-derived neurotrophic factor (BDNF), are potent synaptic modulators that are expressed throughout the forebrain and play critical roles in many behavioral processes. Although the effects of BDNF at excitatory synapses have been well characterized, the mechanisms of action of BDNF at inhibitory synapses are not well understood. Previously we have found that BDNF suppresses presynaptic GABA release in layer 2/3 of the neocortex via postsynaptic tropomyosin-related kinase receptor B (trkB) receptor-induced release of endocannabinoids. To examine the intracellular signaling pathways that underlie this effect, we used pharmacological approaches and whole cell patch-clamp techniques in layer 2/3 pyramidal neurons of somatosensory cortex in brain slices from juvenile Swiss CD1 mice. Our results indicated that phospholipase Cγ (PLCγ) is involved in the CB1 receptor-mediated synaptic effect of BDNF, because the BDNF effect was blocked in the presence of the broad-spectrum PLC inhibitors U-73122 and edelfosine, whereas the inactive analog U-73343 did not alter the suppressive effect of BDNF at inhibitory synapses. Endocannabinoid release can also be triggered by metabotropic glutamate receptor (mGluR)-mediated activation of PLCβ, and BDNF has been shown to enhance spontaneous glutamate release. An mGluR antagonist, E4CPG, however, did not block the BDNF effect. In addition, the effect of BDNF was independent of other signaling pathways downstream of trkB receptor activation, namely, mitogen-activated protein kinase and phosphoinositide 3-kinase pathways, as well as protein kinase C signaling.

Physiology, Pharmacology, and Topography of Cholinergic Neocortical Oscillations In Vitro

1997 ◽  
Vol 77 (5) ◽  
pp. 2427-2445 ◽  
Author(s):  
Heath S. Lukatch ◽  
M. Bruce Maciver
Keyword(s):  
Current Source ◽  
Brain Slices ◽  
Receptor Activation ◽  
Brain Regions ◽  
Oscillatory Activity ◽  
Cortical Layers ◽  
Eeg Activity ◽  
Layer 2

Lukatch, Heath S. and M. Bruce MacIver. Physiology, pharmacology, and topography of cholinergic neocortical oscillations in vitro. J. Neurophysiol. 77: 2427–2445, 1997. Rat neocortical brain slices generated rhythmic extracellular field [microelectroencephalogram (micro-EEG)] oscillations at theta frequencies (3–12 Hz) when exposed to pharmacological conditions that mimicked endogenous ascending cholinergic and GABAergic inputs. Use of the specific receptor agonist and antagonist carbachol and bicuculline revealed that simultaneous muscarinic receptor activation and γ-aminobutyric acid-A (GABAA)-mediated disinhibition werenecessary to elicit neocortical oscillations. Rhythmic activity was independent of GABAB receptor activation, but required intact glutamatergic transmission, evidenced by blockade or disruption of oscillations by 6-cyano-7-nitroquinoxaline-2,3-dione and (±)-2-amino-5-phosphonovaleric acid, respectively. Multisite mapping studies showed that oscillations were localized to areas 29d and 18b (Oc2MM) and parts of areas 18a and 17. Peak oscillation amplitudes occurred in layer 2/3, and phase reversals were observed in layers 1 and 5. Current source density analysis revealed large-amplitude current sinks and sources in layers 2/3 and 5, respectively. An initial shift in peak inward current density from layer 1 to layer 2/3 indicated that two processes underlie an initial depolarization followed by oscillatory activity. Laminar transections localized oscillation-generating circuitry to superficial cortical layers and sharp-spike-generating circuitry to deep cortical layers. Whole cell recordings identified three distinct cell types based on response properties during rhythmic micro-EEG activity: oscillation-on (theta-on) and -off (theta-off) neurons, and transiently depolarizing glial cells. Theta-on neurons displayed membrane potential oscillations that increased in amplitude with hyperpolarization (from −30 to −90 mV). This, taken together with a glutamate antagonist-induced depression of rhythmic micro-EEG activity, indicated that cholinergically driven neocortical oscillations require excitatory synaptic transmission. We conclude that under the appropriate pharmacological conditions, neocortical brain slices were capable of producing localized theta frequency oscillations. Experiments examining oscillation physiology, pharmacology, and topography demonstrated that neocortical brain slice oscillations share many similarities with the in vivo and in vitro theta EEG activity recorded in other brain regions.

scholarly journals TRAF6-Dependent Mitogen-Activated Protein Kinase Activation Differentially Regulates the Production of Interleukin-12 by Macrophages in Response to Toxoplasma gondii

2004 ◽  
Vol 72 (10) ◽  
pp. 5662-5667 ◽  
Author(s):  
Nicola J. Mason ◽  
Jim Fiore ◽  
Takashi Kobayashi ◽  
Katherine S. Masek ◽  
Yongwon Choi ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Toxoplasma Gondii ◽  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Interleukin 12 ◽  
Wild Type ◽  
Kinase Activation ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

ABSTRACT The production of interleukin-12 (IL-12) is critical to the development of innate and adaptive immune responses required for the control of intracellular pathogens. Many microbial products signal through Toll-like receptors (TLR) and activate NF-κB family members that are required for the production of IL-12. Recent studies suggest that components of the TLR pathway are required for the production of IL-12 in response to the parasite Toxoplasma gondii; however, the production of IL-12 in response to this parasite is independent of NF-κB activation. The adaptor molecule TRAF6 is involved in TLR signaling pathways and associates with serine/threonine kinases involved in the activation of both NF-κB and mitogen-activated protein kinase (MAPK). To elucidate the intracellular signaling pathways involved in the production of IL-12 in response to soluble toxoplasma antigen (STAg), wild-type and TRAF6−/− mice were inoculated with STAg, and the production of IL-12(p40) was determined. TRAF6−/− mice failed to produce IL-12(p40) in response to STAg, and TRAF6−/− macrophages stimulated with STAg also failed to produce IL-12(p40). Studies using Western blot analysis of wild-type and TRAF6−/− macrophages revealed that stimulation with STAg resulted in the rapid TRAF6-dependent phosphorylation of p38 and extracellular signal-related kinase, which differentially regulated the production of IL-12(p40). The studies presented here demonstrate for the first time that the production of IL-12(p40) in response to toxoplasma is dependent upon TRAF6 and p38 MAPK.

scholarly journals Nanodelivery Systems Targeting Epidermal Growth Factor Receptors for Glioma Management

Pharmaceutics ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1198
Author(s):  
Sathishbabu Paranthaman ◽  
Meghana Goravinahalli Shivananjegowda ◽  
Manohar Mahadev ◽  
Afrasim Moin ◽  
Shivakumar Hagalavadi Nanjappa ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Growth Factor ◽  
Protein Kinase ◽  
Cell Surface ◽  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Future Research ◽  
Extensive Literature ◽  
Egfr Tkis

A paradigm shift in treating the most aggressive and malignant form of glioma is continuously evolving; however, these strategies do not provide a better life and survival index. Currently, neurosurgical debulking, radiotherapy, and chemotherapy are the treatment options available for glioma, but these are non-specific in action. Patients invariably develop resistance to these therapies, leading to recurrence and death. Receptor Tyrosine Kinases (RTKs) are among the most common cell surface proteins in glioma and play a significant role in malignant progression; thus, these are currently being explored as therapeutic targets. RTKs belong to the family of cell surface receptors that are activated by ligands which in turn activates two major downstream signaling pathways via Rapidly Accelerating Sarcoma/mitogen activated protein kinase/extracellular-signal-regulated kinase (Ras/MAPK/ERK) and phosphatidylinositol 3-kinase/a serine/threonine protein kinase/mammalian target of rapamycin (PI3K/AKT/mTOR). These pathways are critically involved in regulating cell proliferation, invasion, metabolism, autophagy, and apoptosis. Dysregulation in these pathways results in uncontrolled glioma cell proliferation, invasion, angiogenesis, and cancer progression. Thus, RTK pathways are considered a potential target in glioma management. This review summarizes the possible risk factors involved in the growth of glioblastoma (GBM). The role of RTKs inhibitors (TKIs) and the intracellular signaling pathways involved, small molecules under clinical trials, and the updates were discussed. We have also compiled information on the outcomes from the various endothelial growth factor receptor (EGFR)–TKIs-based nanoformulations from the preclinical and clinical points of view. Aided by an extensive literature search, we propose the challenges and potential opportunities for future research on EGFR–TKIs-based nanodelivery systems.

scholarly journals Activation of Intracellular Signaling Pathways by the Murine Cytomegalovirus G Protein-Coupled Receptor M33 Occurs via PLC-β/PKC-Dependent and -Independent Mechanisms

2009 ◽  
Vol 83 (16) ◽  
pp. 8141-8152 ◽  
Author(s):  
Joseph D. Sherrill ◽  
Melissa P. Stropes ◽  
Olivia D. Schneider ◽  
Diana E. Koch ◽  
Fabiola M. Bittencourt ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Kinase ◽  
Signaling Pathways ◽  
G Protein ◽  
Intracellular Signaling ◽  
Murine Cytomegalovirus ◽  
Dependent Manner ◽  
G Protein Coupled Receptor ◽  
G Protein Coupled

ABSTRACT The presence of numerous G protein-coupled receptor (GPCR) homologs within the herpesvirus genomes suggests an essential role for these genes in viral replication in the infected host. Such is the case for murine cytomegalovirus (MCMV), where deletion of the M33 GPCR or replacement of M33 with a signaling defective mutant has been shown to severely attenuate replication in vivo. In the present study we utilized a genetically altered version of M33 (termed R131A) in combination with pharmacological inhibitors to further characterize the mechanisms by which M33 activates downstream signaling pathways. This R131A mutant of M33 fails to support salivary gland replication in vivo and, as such, is an important tool that can be used to examine the signaling activities of M33. We show that M33 stimulates the transcription factor CREB via heterotrimeric Gq/11 proteins and not through promiscuous coupling of M33 to the Gs pathway. Using inhibitors of signaling molecules downstream of Gq/11, we demonstrate that M33 stimulates CREB transcriptional activity in a phospholipase C-β and protein kinase C (PKC)-dependent manner. Finally, utilizing wild-type and R131A versions of M33, we show that M33-mediated activation of other signaling nodes, including the mitogen-activated protein kinase family member p38α and transcription factor NF-κB, occurs in the absence of Gq/11 and PKC signaling. The results from the present study indicate that M33 utilizes multiple mechanisms to modulate intracellular signaling cascades and suggest that signaling through PLC-β and PKC plays a central role in MCMV pathogenesis in vivo.

Abstract 515: Aldosterone Modulates Endothelial Paracellular Permeability by Opening Intercellular Junctions

Hypertension ◽  
2012 ◽  
Vol 60 (suppl_1) ◽  
Author(s):  
Torsten Kirsch ◽  
Uwe Klinge ◽  
Joon-Keun Park ◽  
Marion Haubitz ◽  
Hermann Haller ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Signaling Pathways ◽  
Intracellular Signaling ◽  
Ex Vivo ◽  
Umbilical Vein ◽  
Intercellular Junctions ◽  
Paracellular Permeability ◽  
Cortical Actin ◽  
Umbilical Vein Endothelial Cells ◽  
Endothelial Integrity

Aldosterone (Ald) is involved in vascular remodeling and inflammation; however, the mechanisms are imperfectly defined. We hypothesized that Ald alters endothelial integrity and modifies paracellular permeability. Human umbilical vein endothelial cells (HUVEC) were exposed to Ald (10 -9 mol/L) and alterations in paracellular permeability, assembly of tight and adherens junctions, and activation of intracellular signaling pathways were determined. Ald increased endothelial paracellular permeability for molecules up to 70 kDa within 60 min. A transient loss of cortical actin with formation of actin stress fibers, and disruption of continuous adherens and tight junction strands, accompanied the changes. Mineralocorticoid receptor (MR) blockade, inhibition of RhoA or disruption of extracellular regulated protein kinase (ERK) 1/2 signaling pathways attenuated the Ald-related effects. Moreover, the observed changes of the actin cytoskeleton and intercellular junction architecture were accompanied by a rapid dephosphorylation of protein kinase B (AKT) as well as deactivation of endothelial NO synthase (eNOS). Ex vivo tracer flux experiments with Evans Blue (EB)-conjugated albumin demonstrated concordant response to Ald in freshly isolated umbilical arteries. In summary, Ald leads to increased permeability of endothelial monolayer or isolated arteries. These alterations are associated with a temporal opening of Intercellular junctions and diminished eNOS activity, and depend on activation of the RhoA/ERK pathway. We conclude that these mechanisms could contribute to Ald-induced vasculopathy.

Low-frequency stimulation evokes serotonin release in the nucleus accumbens and induces long-term depression via production of endocannabinoid

2014 ◽  
Vol 111 (5) ◽  
pp. 1046-1055 ◽  
Author(s):  
Costanza Burattini ◽  
Giulia Battistini ◽  
Francesco Tamagnini ◽  
Giorgio Aicardi
Keyword(s):  
Nucleus Accumbens ◽  
Glutamate Release ◽  
Brain Slices ◽  
Low Frequency ◽  
Receptor Activation ◽  
Serotonin Release ◽  
Long Term Depression ◽  
Voltage Gated ◽  
Frequency Stimulation

The nucleus accumbens (NAc), a major component of the mesolimbic system, is involved in the mediation of reinforcing and addictive properties of many dependence-producing drugs. Glutamatergic synapses within the NAc can express plasticity, including a form of endocannabinoid (eCB)-long-term depression (LTD). Recent evidences demonstrate cross talk between eCB signaling pathways and those of other receptor systems, including serotonin (5-HT); the extensive colocalization of CB1 and 5-HT receptors within the NAc suggests the potential for interplay between them. In the present study, we found that 20-min low-frequency (4 Hz) stimulation (LFS-4Hz) of glutamatergic afferences in rat brain slices induces a novel form of eCB-LTD in the NAc core, which requires 5-HT2 and CB1 receptor activation and L-type voltage-gated Ca2+ channel opening. Moreover, we found that exogenous 5-HT application (5 μM, 20 min) induces an analogous LTD (5-HT-LTD) at the same synapses, requiring the activation of the same receptors and the opening of the same Ca2+ channels; LFS-4Hz-LTD and 5-HT-LTD were mutually occlusive. Present results suggest that LFS-4Hz induces the release of 5-HT, which acts at 5-HT2 postsynaptic receptors, increasing Ca2+ influx through L-type voltage-gated channels and 2-arachidonoylglycerol production and release; the eCB travels retrogradely and binds to presynaptic CB1 receptors, causing a long-lasting decrease of glutamate release, resulting in LTD. These observations might be helpful to understand the neurophysiological mechanisms underlying drug addiction, major depression, and other psychiatric disorders characterized by dysfunction of 5-HT neurotransmission in the NAc.

scholarly journals Enhanced Parenchymal Arteriole Tone and Astrocyte Signaling Protect Neurovascular Coupling Mediated Parenchymal Arteriole Vasodilation in the Spontaneously Hypertensive Rat

2015 ◽  
Vol 35 (7) ◽  
pp. 1127-1136 ◽  
Author(s):  
Jennifer A Iddings ◽  
Ki Jung Kim ◽  
Yiqiang Zhou ◽  
Haruki Higashimori ◽  
Jessica A Filosa
Keyword(s):  
Smooth Muscle ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cell ◽  
Muscle Cell ◽  
Vascular Smooth Muscle Cell ◽  
Metabotropic Glutamate Receptor ◽  
Brain Slices ◽  
Neurovascular Coupling ◽  
Receptor Activation ◽  
Spontaneously Hypertensive

Functional hyperemia is the regional increase in cerebral blood flow upon increases in neuronal activity which ensures that the metabolic demands of the neurons are met. Hypertension is known to impair the hyperemic response; however, the neurovascular coupling mechanisms by which this cerebrovascular dysfunction occurs have yet to be fully elucidated. To determine whether altered cortical parenchymal arteriole function or astrocyte signaling contribute to blunted neurovascular coupling in hypertension, we measured parenchymal arteriole reactivity and vascular smooth muscle cell Ca2+ dynamics in cortical brain slices from normotensive Wistar Kyoto (WKY) and spontaneously hypertensive (SHR) rats. We found that vasoconstriction in response to the thromboxane A2 receptor agonist U46619 and basal vascular smooth muscle cell Ca2+ oscillation frequency were significantly increased in parenchymal arterioles from SHR. In perfused and pressurized parenchymal arterioles, myogenic tone was significantly increased in SHR. Although K+-induced parenchymal arteriole dilations were similar in WKY and SHR, metabotropic glutamate receptor activation-induced parenchymal arteriole dilations were enhanced in SHR. Further, neuronal stimulation-evoked parenchymal arteriole dilations were similar in SHR and WKY. Our data indicate that neurovascular coupling is not impaired in SHR, at least at the level of the parenchymal arterioles.

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