scholarly journals BDNF Evokes Release of Endogenous Cannabinoids at Layer 2/3 Inhibitory Synapses in the Neocortex

2010 ◽  
Vol 104 (4) ◽  
pp. 1923-1932 ◽  
Author(s):  
Fouad Lemtiri-Chlieh ◽  
Eric S. Levine
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Cannabinoid Receptor ◽  
Gaba Release ◽  
Receptor Activation ◽  
Potential Interaction ◽  
Inhibitory Synapses ◽  
Cb1 Receptors ◽  
Layer 2 ◽  
Underlying Mechanisms

The neurotrophin brain-derived neurotrophic factor (BDNF) is a potent regulator of inhibitory synaptic transmission, although the locus of this effect and the underlying mechanisms are controversial. We explored a potential interaction between BDNF and endogenous cannabinoid (endocannabinoid) signaling because activation of type 1 cannabinoid (CB1) receptors potently regulates γ-aminobutyric acid (GABA) release and both trkB tyrosine kinase receptors and CB1 receptors are highly expressed at synapses in neocortical layer 2/3. Here, we found that the effects of BDNF at inhibitory cortical synapses are mediated by the release of endocannabinoids acting retrogradely at presynaptic CB1 receptors. Specifically, acute application of BDNF rapidly reduced the amplitude of inhibitory postsynaptic currents (IPSCs) via postsynaptic trkB receptor activation because intracellular delivery of the tyrosine kinase inhibitor K252a completely blocked the BDNF effect. Although triggered by postsynaptic trkB activation, BDNF exposure decreased presynaptic release probability, as evidenced by increases in the paired-pulse ratio and coefficient of variation of evoked responses. In addition, BDNF decreased the frequency but not the amplitude of action potential–independent miniature IPSCs and BDNF did not alter the postsynaptic response to locally applied GABA. These results suggest that BDNF induces the release of a retrograde messenger from the postsynaptic cell that regulates presynaptic neurotransmitter release. Consistent with a role for endocannabinoids as the retrograde signal, the effect of BDNF on IPSCs was blocked by CB1 receptor antagonists and was occluded by a cannabinoid receptor agonist. Furthermore, inhibiting endocannabinoid synthesis or transport also disrupted the BDNF effect, implicating postsynaptic endocannabinoid release triggered by BDNF.

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.

Lack of Depolarization-Induced Suppression of Inhibition (DSI) in Layer 2/3 Interneurons That Receive Cannabinoid-Sensitive Inhibitory Inputs

2007 ◽  
Vol 98 (5) ◽  
pp. 2517-2524 ◽  
Author(s):  
Fouad Lemtiri-Chlieh ◽  
Eric S. Levine
Keyword(s):  
Action Potentials ◽  
Pyramidal Neurons ◽  
Cannabinoid Receptor ◽  
Brain Slices ◽  
Gaba Release ◽  
Synaptic Activity ◽  
Layer 2 ◽  
Fast Spiking ◽  
Whole Cell Recordings

In layer 2/3 of neocortex, brief trains of action potentials in pyramidal neurons (PNs) induce the mobilization of endogenous cannabinoids (eCBs), resulting in a depression of GABA release from the terminals of inhibitory interneurons (INs). This depolarization-induced suppression of inhibition (DSI) is mediated by activation of the type 1 cannabinoid receptor (CB1) on presynaptic terminals of a subset of INs. However, it is not clear whether CB1 receptors are also expressed at synapses between INs, and whether INs can release eCBs in response to depolarization. In the present studies, brain slices containing somatosensory cortex were prepared from 14- to 21-day-old CD-1 mice. Whole cell recordings were obtained from layer 2/3 PNs and from INs classified as regular spiking nonpyramidal, irregular spiking, or fast spiking. For all three classes of INs, the cannabinoid agonist WIN55,212-2 suppressed inhibitory synaptic activity, similar to the effect seen in PNs. In addition, trains of action potentials in PNs resulted in significant DSI. In INs, however, DSI was not seen in any cell type, even with prolonged high-frequency spike trains that produced calcium increases comparable to that seen with DSI induction in PNs. In addition, blocking eCB reuptake with AM404, which enhanced DSI in PNs, failed to unmask any DSI in INs. Thus the lack of DSI in INs does not appear to be due to an insufficient increase in intracellular calcium or enhanced reuptake. These results suggest that layer 2/3 INs receive CB1-expressing inhibitory inputs, but that eCBs are not released by these INs.

Role of tyrosine kinase and p44/42 MAPK in D2-like receptor-mediated stimulation of Na+, K+-ATPase in kidney

2002 ◽  
Vol 282 (4) ◽  
pp. F697-F702 ◽  
Author(s):  
Vihang Narkar ◽  
Tahir Hussain ◽  
Mustafa Lokhandwala
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Mapk Pathway ◽  
Rat Kidney ◽  
Receptor Activation ◽  
Proximal Tubules ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Stimulation Of

Our laboratory has shown that dopamine D2-like receptor activation causes stimulation of Na+, K+-ATPase (NKA) activity in the proximal tubules of the rat kidney. The present study was designed to investigate the cellular signaling mechanisms mediating this response to D2-like receptor activation. We measured the stimulation of NKA activity by bromocriptine (D2-like receptor agonist) in the absence and presence of PD-98059 [p44/42 mitogen-activated protein kinase (MAPK) kinase inhibitor] and genistein (tyrosine kinase inhibitor) in renal proximal tubules. Both agents inhibited bromocriptine-mediated stimulation of NKA, suggesting the involvement of p44/42 MAPK and tyrosine kinase in this response. Additionally, we found that bromocriptine increased the phosphorylation of p44/42 MAPK in the proximal tubules, which was blocked by PD-98059 and genistein. These results show that D2-like receptor activation causes stimulation of NKA activity by means of a tyrosine kinase-p44/42 MAPK pathway in the proximal tubules of the kidney.

Modeling targeted inhibition of wild type and mutated c-MET receptor

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 14010-14010
Author(s):  
P. C. Ma ◽  
S. Jiang ◽  
R. Du ◽  
S. Dietrich ◽  
Z. Tang ◽  
...  
Keyword(s):  
Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Receptor Activation ◽  
Kinase Domain ◽  
Cell System ◽  
Tyrosine Kinase Domain ◽  
Wild Type ◽  
Juxtamembrane Domain ◽  
Met Receptor

14010 Background: c-MET belongs to the semaphorin superfamily of signaling proteins, containing three protein families (semaphorins, plexins, c-MET and RON) that have central roles in cell signaling. The c-MET receptor tyrosine kinase is involved in regulating cell growth/proliferation, survival, angiogenesis, cell scattering, cell motility and migration. Mutations in c-MET have been identified in various human cancers including lung cancer and papillary renal cell carcinomas. c-MET mutations occur within the extracellular seven-blade β-propeller fold sema domain (E168D, L229F, S325G, N375S), juxtamembrane domain (R988C, T1010I), and kinase domain (M1268T). We hypothesized that these mutations would have differential effects on the kinase inhibition. Methods: We modeled the various c-MET mutations from different functional domains of the receptor using a G418-resistant stable Cos-7 transfection cell system to determine their effect on sensitivity to a selective c-MET kinase inhibitor SU11274. Sensitivity to SU11274 inhibition was assayed by phospho-immunoblotting using phospho- specific antibody against the major tyrosine kinase phosphorylation epitopes pY1234/1235 of the c-MET kinase in vitro. Results: First, we identified that mutations in the sema and juxtamembrane domain were activating as defined by ligand-independent constitutive receptor activation. SU11274 was capable of inhibiting ligand induced signaling through the wild-type c-MET as well as mutant c-MET receptors harboring mutations in the sema, juxtamembrane and tyrosine kinase domain. However, SU11274 inhibition of mutant c-MET was mutation-dependent, with the juxtamembrane domain mutations R988C and T1010I resulting in a receptor form that was less sensitive to SU11274. Mutations in the sema and kinase domain also resulted in varying sensitivity to inhibition by SU11274 inhibition. Conclusions: Mutations in the sema and juxtamembrane domain of c-MET result in receptor activation. The small molecule inhibitor SU11274 is active against wild type and mutated c- MET receptor. Further studies to characterize the signaling effects and the mechanism of sensitivity and resistance of c-MET mutations to specific inhibitors are crucial in the successful development of therapeutic c-MET and mutant c-MET inhibitors. No significant financial relationships to disclose.

Cannabinoid Receptor Activation Differentially Modulates Ion Channels in Photoreceptors of the Tiger Salamander

2003 ◽  
Vol 89 (5) ◽  
pp. 2647-2654 ◽  
Author(s):  
Alex Straiker ◽  
Jane M. Sullivan
Keyword(s):  
Synaptic Transmission ◽  
Cannabinoid Receptor ◽  
Potassium Currents ◽  
Receptor Activation ◽  
Bipolar Cells ◽  
Calcium Currents ◽  
Cb1 Receptors ◽  
Tiger Salamander ◽  
Cone Photoreceptors ◽  
Rod And Cone Photoreceptors

Cannabinoid CB1 receptors have been detected in retinas of numerous species, with prominent labeling in photoreceptor terminals of the chick and monkey. CB1 labeling is well-conserved across species, suggesting that CB1 receptors might also be present in photoreceptors of the tiger salamander. Synaptic transmission in vertebrate photoreceptors is mediated by L-type calcium currents—currents that are modulated by CB1 receptors in bipolar cells of the tiger salamander. Presence of CB1 receptors in photoreceptor terminals would therefore be consistent with presynaptic modulation of synaptic transmission, a role seen for cannabinoids in other parts of the brain. Here we report immunohistochemical and electrophysiological evidence for the presence of functional CB1 receptors in rod and cone photoreceptors of the tiger salamander. The cannabinoid receptor agonist WIN 55212-2 enhances calcium currents of rod photoreceptors by 39% but decreases calcium currents of large single cones by 50%. In addition, WIN 55212-2 suppresses potassium currents of rods and large single cones by 44 and 48%, respectively. Thus functional CB1 receptors, present in the terminals of rod and cone photoreceptors, differentially modulate calcium and potassium currents in rods and large single cones. CB1 receptors are therefore well positioned to modulate neurotransmitter release at the first synapse of the visual system.

Dextran sulphate induces fibrinogen receptor activation through a novel Syk-independent PI-3 kinase-mediated tyrosine kinase pathway in platelets

2013 ◽  
Vol 109 (06) ◽  
pp. 1131-1140 ◽  
Author(s):  
Todd M. Getz ◽  
Bhanu Manne ◽  
Lorena Buitrago ◽  
Yingying Mao ◽  
Satya P. Kunapuli
Keyword(s):  
Platelet Aggregation ◽  
Tyrosine Kinase ◽  
Kinase Inhibitor ◽  
Receptor Activation ◽  
Dependent Manner ◽  
Akt Phosphorylation ◽  
Glycoprotein Vi ◽  
Fibrinogen Receptor ◽  
Adp Receptor Antagonists ◽  
Kinase Pathway

SummaryIn our attempt to find a physiological agonist that activates PAR3 receptors, we screened several coagulation proteases using PAR4 null platelets. We observed that FXIIa and heat inactivated FXIIa, but not FXII, caused platelet aggregation. We have identified a contaminant activating factor in FXIIa preparation as dextran sulfate (DxS), which caused aggregation of both human and mouse platelets. DxS-induced platelet aggregation was unaffected by YM254890, a Gq inhibitor, but abolished by pan-Src family kinase (SFK) inhibitor PP2, suggesting a role for SFKs in this pathway. However, DxS-induced platelet aggregation was unaffected in FcRγ-chain null murine platelets, ruling out the possibility of glycoprotein VI-mediated events. More interesting, OXSI-2 and Go6976, two structurally unrelated inhibitors shown to affect Syk, had only a partial effect on DxS-induced PAC-1 binding. DxS-induced platelet aggregation and intracellular calcium increases were abolished by the pan PI-3 kinase inhibitor LY294002, or an isoform-specific PI-3 kinase β inhibitor TGX-221. Pretreatment of platelets with Syk inhibitors or ADP receptor antagonists had little effect on Akt phosphorylation following DxS stimulation. These results, for the first time, establish a novel tyrosine kinase pathway in platelets that causes fibrinogen receptor activation in a PI-3 kinase-dependent manner without a crucial role for Syk.

scholarly journals Cholinergic mechanisms of high-frequency stimulation in entopeduncular nucleus

2016 ◽  
Vol 115 (1) ◽  
pp. 60-67 ◽  
Author(s):  
Feng Luo ◽  
Zelma H. T. Kiss
Keyword(s):  
High Frequency ◽  
Receptor Activation ◽  
Inhibitory Synapses ◽  
High Frequency Stimulation ◽  
Entopeduncular Nucleus ◽  
Cellular Mechanisms ◽  
Cholinergic Mechanism ◽  
Whole Cell Patch Clamp ◽  
Frequency Stimulation ◽  
Underlying Mechanisms

Chronic, high-frequency (>100 Hz) electrical stimulation, known as deep brain stimulation (DBS), of the internal segment of the globus pallidus (GPi) is a highly effective therapy for Parkinson's disease (PD) and dystonia. Despite some understanding of how it works acutely in PD models, there remain questions about its mechanisms of action. Several hypotheses have been proposed, such as depolarization blockade, activation of inhibitory synapses, depletion of neurotransmitters, and/or disruption/alteration of network oscillations. In this study we investigated the cellular mechanisms of high-frequency stimulation (HFS) in entopeduncular nucleus (EP; rat equivalent of GPi) neurons using whole cell patch-clamp recordings. We found that HFS applied inside the EP nucleus induced a prolonged afterdepolarization that was dependent on stimulation frequency, pulse duration, and current amplitude. The high frequencies (>100 Hz) and pulse widths (>0.15 ms) used clinically for dystonia DBS could reliably induce these afterdepolarizations, which persisted under blockade of ionotropic glutamate (kynurenic acid, 2 mM), GABAA (picrotoxin, 50 μM), GABAB (CGP 55845, 1 μM), and acetylcholine nicotinic receptors (DHβE, 2 μM). However, this effect was blocked by atropine (2 μM; nonselective muscarinic antagonist) or tetrodotoxin (0.5 μM). Finally, the muscarinic-dependent afterdepolarizations were sensitive to Ca2+-sensitive nonspecific cationic (CAN) channel blockade. Hence, these data suggest that muscarinic receptor activation during HFS can lead to feedforward excitation through the opening of CAN channels. This study for the first time describes a cholinergic mechanism of HFS in EP neurons and provides new insight into the underlying mechanisms of DBS.

Tyrosine kinase inhibitors reduce bcl-2 expression and induce apoptosis in androgen-dependent cells

2000 ◽  
Vol 278 (1) ◽  
pp. C66-C72 ◽  
Author(s):  
Takashi Ohigashi ◽  
Munehisa Ueno ◽  
Shoichi Nonaka ◽  
Takashi Nakanoma ◽  
Yusuke Furukawa ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Kinase Inhibitors ◽  
Kinase Inhibitor ◽  
Flow Cytometric Analysis ◽  
Signal Transduction Pathway ◽  
Receptor Activation ◽  
Dependent Manner ◽  
Induced Apoptosis

The signal transduction pathway showing how androgen withdrawal induces apoptosis in androgen-dependent cells has not been clearly understood. In these studies, we focused on the behavior of tyrosine kinases in androgen-dependent cells and investigated its correlation with apoptosis and bcl-2 expression. We used SC2G, an androgen-dependent mouse mammary carcinoma cell line, which had been cloned from Shionogi Carcinoma 115 (SC115). When SC2G cells were cultured with herbimycin A (HMA), a potent tyrosine kinase inhibitor, the number of viable cells decreased significantly after 24 h. Terminal deoxyribonucleotidyltransferase-mediated dUTP-biotin nick end labeling and flow cytometric analysis of annexin V staining showed that HMA induced apoptosis of SC2G cells. The level of bcl-2 mRNA in SC2G cells was suppressed by HMA in a dose-dependent manner on RT-PCR. Preincubation with caspase inhibitors protected HMA-induced apoptosis of SC2G cells. When a human bcl-2 gene was transfected in SC2G cells and overexpressed, SC2G cells seemed to acquire tolerance for HMA. These data indicate that HMA-sensitive tyrosine kinase(s) can regulate apoptosis and inhibit bcl-2 expression in SC2G mouse androgen-dependent cells. Tyrosine kinase(s) seemed to be a member of signal transduction between androgen receptor activation and bcl-2 expression.

scholarly journals Cannabinoids Depress Inhibitory Synaptic Inputs Received by Layer 2/3 Pyramidal Neurons of the Neocortex

2002 ◽  
Vol 88 (1) ◽  
pp. 534-539 ◽  
Author(s):  
Joseph Trettel ◽  
Eric S. Levine
Keyword(s):  
Pyramidal Neurons ◽  
Cannabinoid Receptor ◽  
Cell Voltage ◽  
Gaba Release ◽  
Inhibitory Postsynaptic Currents ◽  
Postsynaptic Currents ◽  
Presynaptic Site ◽  
Layer 2 ◽  
Kinetics Of

Using whole cell voltage-clamp recordings we investigated the effects of a synthetic cannabinoid (WIN55,212-2) on inhibitory inputs received by layer 2/3 pyramidal neurons in slices of the mouse auditory cortex. Activation of the type 1 cannabinoid receptor (CB1R) with WIN55,212-2 reliably reduced the amplitude of GABAergic inhibitory postsynaptic currents evoked by extracellular stimulation within layer 2/3. The suppression of this inhibition was blocked and reversed by the highly selective CB1R antagonist AM251, confirming a CB1R-mediated inhibition. Pairing evoked inhibitory postsynaptic currents (IPSCs) at short interstimulus intervals while applying WIN55,212-2 resulted in an increase in paired-pulse facilitation suggesting that the probability of GABA release was reduced. A presynaptic site of cannabinoid action was verified by an observed decrease in the frequency with no change in the amplitude or kinetics of action potential–independent postsynaptic currents (mIPSCs). When Cd2+ was added or Ca2+ was omitted from the recording solution, the remaining fraction of Ca2+-independent mIPSCs did not respond to WIN55,212-2. These data suggest that cannabinoids are capable of suppressing the inhibition of neocortical pyramidal neurons by depressing Ca2+-dependent GABA release from local interneurons.

scholarly journals Axonal CB1 receptors mediate inhibitory bouton formation via cAMP increase

2021 ◽  
Author(s):  
Jian Liang ◽  
Dennis LH Kruijssen ◽  
Aniek CJ Verschuuren ◽  
Bas JB Voesenek ◽  
Feline Benavides ◽  
...  
Keyword(s):  
Synapse Formation ◽  
Underlying Mechanism ◽  
Receptor Activation ◽  
Cb1 Receptor ◽  
Inhibitory Synapses ◽  
Cb1 Receptors ◽  
Protein Signaling ◽  
Two Photon Microscopy ◽  
Excitatory Activity ◽  
Camp Levels

AbstractExperience-dependent formation and removal of synapses are essential throughout life. For instance, GABAergic synapses are removed to facilitate learning, and strong excitatory activity is accompanied by formation of inhibitory synapses. We recently discovered that active dendrites trigger the growth of inhibitory synapses via CB1 receptor-mediated endocannabinoid signaling, but the underlying mechanism remained unclear. Using two-photon microscopy to monitor the formation of individual inhibitory boutons, we found that CB1 receptor activation mediated formation of inhibitory boutons and promoted their subsequent stabilization. Inhibitory bouton formation did not require neuronal activity and was independent of Gi/o protein signaling, but was directly induced by elevating cAMP levels using forskolin and by activating Gs proteins using DREADDs. Our findings reveal that axonal CB1 receptors signal via unconventional downstream pathways and that inhibitory bouton formation is triggered by an increase in axonal cAMP levels. Our results demonstrate a novel role for axonal CB1 receptors in axon-specific, and context-dependent, inhibitory synapse formation.

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