Retrograde Endocannabinoid Research Articles

Genetic variations in the retrograde endocannabinoid signaling pathway in Chinese patients with major depressive disorder.

The retrograde endocannabinoid (eCB) pathway is closely associated with the etiology of major depressive disorder (MDD) at both pathophysiological and genetic levels. This study aimed to investigate the potential role of genetic mutations in the eCB pathway and underlying mechanisms in Han Chinese patients with MDD. A total of 96 drug-naïve patients with first-episode MDD and 62 healthy controls (HCs) were recruited. Whole-exome sequencing was performed to identify the gene mutation profiles in patients with MDD. Results were filtered to focus on low-frequency variants and rare mutations (minor allele frequencies <0.05) related to depressive phenotypes. Enrichment analyses were performed for 146 selected genes to examine the pathways in which the most significant enrichment occurred. A protein-protein interaction (PPI) network analysis was performed to explore the biological functions of the eCB pathway. Finally, based on current literature, a preliminary analysis was conducted to explore the effect of genetic mutations on the function of this pathway. Our analysis identified 146 (15.02%) depression-related genetic mutations in patients with MDD when compared with HCs, and 37 of the mutations were enriched in the retrograde eCB signaling pathway. Seven hub genes in the eCB pathway were closely related to mitochondrial function, including Complex I genes (NDUFS4, NDUFV2, NDUFA2, NDUFA12, NDUFB11) and genes associated with protein (PARK7) and enzyme (DLD) function in the regulation of mitochondrial oxidative stress. These results indicate that genetic mutations in the retrograde eCB pathway represent potential etiological factors associated with the pathogenesis of MDD.

Male mice exposed to chronic intermittent ethanol exposure exhibit significant upregulation or downregulation of circular RNAs

ABSTRACT B a ckground: Circular RNAs (circRNAs) have been crucially implicated in various diseases, however, their involvement in chronic intermittent ethanol (CIE) exposure remains unclear. O bjective: The present study was conducted to evaluate the circular RNA expression alteration in brain samples and to identify the molecular mechanisms underlying chronic intermittent ethanol exposure. M ethods: Male C57BL/6J mice (10 for each group) were given 4 weeks of chronic intermittent ethanol exposure. Whole brain samples were collected for high-throughput sequencing and circRNA bioinformatic analysis. Real-time quantitative PCR (RI-qPCR) and agarose electrophoresis were used to validate the differentially expressed circRNAs. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) analysis were performed. A p level < 0.05 was considered statistically significant. R esults: Compared with the control group and baseline values, the CIE group showed a significant increase in ethanol intake. High-throughput sequencing revealed 399 significantly different circRNAs in CIE mice, including 150 up-regulated circRNAs and 249 down-regulated circRNAs. GO analysis showed that the most significantly enriched term for biological process, cellular component, and molecular function were GO:0050885, GO:0016020 and GO:0005515, respectively. The most enriched pathways in KEGG analysis were GABAergic synapse (mmu04727), followed by retrograde endocannabinoid (eCB) signaling (mmu04723) and morphine addiction (mmu05032). Among the circRNAs, RT-qPCR confirmed 14 upregulated and 13 downregulated circRNAs in the brain tissues with 9 upregulated and 10 downregulated circRNAs being observed in blood samples. C onclusions: Our study suggests that chronic ethanol exposure upregulates or downregulates circRNAs in the brain, which, in turn, could alter neurotransmitter release and signal transduction.

Differential Transcriptome Profiling Unveils Novel Deregulated Gene Signatures Involved in Pathogenesis of Alzheimer's Disease.

Alzheimer’s disease (AD) is a neurodegenerative disorder that is characterized by a progressive loss of cognitive functions at a higher level than normal aging. Although the apolipoprotein (APOE) gene is a major risk factor in developing AD, other genes have also been reported to be linked with complex phenotypes. Therefore, this genome-wide expression study explored differentially expressed genes as possible novel biomarkers involved in AD. The mRNA expression dataset, GSE28146, containing 15 sample data composed of 7 AD cases from the hippocampus region with age-matched control (n = 8, >80 years), was analyzed. Using “affy” R-package, mRNA expression was calculated, while pathway enrichment analysis was performed to determine related biological processes. Of 58 differentially expressed genes, 44 downregulated and 14 upregulated genes were found to be significantly (p < 0.001) altered. The pathway enrichment analysis revealed two altered genes, i.e., dynein light chain 1 (DYNLL1) and kalirin (KLRN), associated with AD in the elderly population. The majority of genes were associated with retrograde endocannabinoid as well as vascular endothelial growth factors affecting the complex phenotypes. The DYNLL1 and KLRN genes may be involved with AD and Huntington’s disease (HD) phenotypes and represent a common genetic basis of these diseases. However, the hallmark of AD is dementia, while the classic motor sign of HD includes chorea. Our data warrant further investigation to identify the role of these genes in disease pathogenesis.

Opposing Retrograde and Astrocyte-Dependent Endocannabinoid Signaling Mechanisms Regulate Lateral Habenula Synaptic Transmission

Opposing Retrograde and Astrocyte-Dependent Endocannabinoid Signaling Mechanisms Regulate Lateral Habenula Synaptic Transmission

Plasma metabolomic profiling in workers with noise-induced hearing loss: a pilot study.

Noise-induced hearing loss (NIHL) remains a leading occupational related disease and is a serious public health problem. Hence, the identification of potential biomarkers for NIHL prevention and diagnosis has become an urgent work. To discover potential metabolic biomarkers of NIHL, plasma metabolomics analysis in 62 NIHL patients and 62 normal hearing controls was performed using ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry (UHPLC-Q-TOF MS). Orthogonal partial least square-discriminant analysis (OPLS-DA) model was applied to distinguish metabolite profile alterations in plasma samples between the two groups. The metabolites with a variable importance of projection (VIP) value > 1 and P value < 0.05 were considered to be potential metabolic biomarkers. KEGG database was performed to explore the involved pathways of potential biomarkers. Three autophagy-related genes (PI3K, AKT, and ATG5) were selected for further verification, and mRNA levels were detected using RT-qPCR analysis. Twenty plasma metabolites with VIP > 1 and P < 0.05 were significantly altered between the two groups. Totally, seven metabolic pathways involving the glycerophospholipid metabolism, glycosylphosphatidylinositol (GPI)-anchor biosynthesis, autophagy pathway, choline metabolism, the alpha-linolenic acid metabolism and linoleic acid metabolism, and retrograde endocannabinoid pathway were significantly related to NIHL. Furthermore, verification by RT-qPCR suggested that the mRNA expression levels of PI3K and AKT along with ATG5 were significantly lower in the NIHL patients compared with controls. In summary, the present study provides the first evidence that the identified aberrantly altered metabolites may be the potentially valuable biomarkers of NIHL for occupational noise-exposed workers. Autophagy signal pathway may be involved in the occurrence and development of NIHL. Moreover, this present study may be helpful to further better understand the metabolic changes in NIHL and be helpful for the understanding of pathogenic mechanism.

Insulin-Like Growth Factor 1 Increases GABAergic Neurotransmission to GnRH Neurons via Suppressing the Retrograde Tonic Endocannabinoid Signaling Pathway in Mice

Introduction: Hypophysiotropic gonadotropin-releasing hormone (GnRH) neurons orchestrate various physiological events that control the onset of puberty. Previous studies showed that insulin-like growth factor 1 (IGF-1) induces the secretion of GnRH and accelerates the onset of puberty, suggesting a regulatory role of this hormone upon GnRH neurons. Methods: To reveal responsiveness of GnRH neurons to IGF-1 and elucidate molecular pathways acting downstream to the IGF-1 receptor (IGF-1R), in vitro electrophysiological experiments were carried out on GnRH-GFP neurons in acute brain slices from prepubertal (23–29 days) and pubertal (50 days) male mice. Results: Administration of IGF-1 (13 nM) significantly increased the firing rate and frequency of spontaneous postsynaptic currents and that of excitatory GABAergic miniature postsynaptic currents (mPSCs). No GABAergic mPSCs were induced by IGF-1 in the presence of the GABA_A-R blocker picrotoxin. The increase in the mPSC frequency was prevented by the use of the IGF-1R antagonist, JB1 (1 µM), or the intracellularly applied PI3K blocker (LY294002, 50 µM), showing involvement of IGF-1R and PI3K in the mechanism. Blockade of the transient receptor potential vanilloid 1, an element of the tonic retrograde endocannabinoid machinery, by AMG9810 (10 µM) or antagonizing the cannabinoid receptor type-1 by AM251 (1 µM) abolished the effect. Discussion/Conclusion: These findings indicate that IGF-1 arrests the tonic retrograde endocannabinoid pathway in GnRH neurons, and this disinhibition increases the release of GABA from presynaptic terminals that, in turn, activates GnRH neurons leading to the fine-tuning of the hypothalamo-pituitary-gonadal axis.

Astrocytes Function as an Intermediate for Retrograde Endocannabinoid Signaling in the Suprachiasmatic Nucleus to Influence Circadian Clock Timing.

Highlighted Research Paper: Cannabinoid Signaling Recruits Astrocytes to Modulate Presynaptic Function in the Suprachiasmatic Nucleus. Lauren M. Hablitz, Ali N. Gunesch, Olga Cravetchi, Michael Moldavan and Charles N. Allen.

Cell signaling dependence of rapid glucocorticoid-induced endocannabinoid synthesis in hypothalamic neuroendocrine cells

Glucocorticoids induce a rapid synthesis of endocannabinoid in hypothalamic neuroendocrine cells by activation of a putative membrane receptor. Somato-dendritically released endocannabinoid acts as a retrograde messenger to suppress excitatory synaptic inputs to corticotropin-releasing hormone-, oxytocin-, and vasopressin-secreting cells. The non-genomic signaling mechanism responsible for rapid endocannabinoid synthesis by glucocorticoids has yet to be fully characterized. Here we manipulated cell signaling molecules pharmacologically using an intracellular approach to elucidate the signaling pathway activated by the membrane glucocorticoid receptor in hypothalamic neuroendocrine cells. We found that rapid glucocorticoid-induced endocannabinoid synthesis in magnocellular neuroendocrine cells requires the sequential activation of multiple kinases, phospholipase C, and intracellular calcium mobilization. While there remain gaps in our understanding, our findings reveal many of the critical players in the rapid glucocorticoid signaling that culminates in the retrograde endocannabinoid modulation of excitatory synaptic transmission.

Kainate Receptors Inhibit Glutamate Release Via Mobilization of Endocannabinoids in Striatal Direct Pathway Spiny Projection Neurons.

Kainate receptors are members of the glutamate receptor family that function by both generating ionotropic currents through an integral ion channel pore and coupling to downstream metabotropic signaling pathways. They are highly expressed in the striatum, yet their roles in regulating striatal synapses are not known. Using mice of both sexes, we demonstrate that GluK2-containing kainate receptors expressed in direct pathway spiny projection neurons (dSPNs) inhibit glutamate release at corticostriatal synapses in the dorsolateral striatum. This inhibition requires postsynaptic kainate-receptor-mediated mobilization of a retrograde endocannabinoid (eCB) signal and activation of presynaptic CB1 receptors. This pathway can be activated during repetitive 25 Hz trains of synaptic stimulation, causing short-term depression of corticostriatal synapses. This is the first study to demonstrate a role for kainate receptors in regulating eCB-mediated plasticity at the corticostriatal synapse and demonstrates an important role for these receptors in regulating basal ganglia circuits.SIGNIFICANCE STATEMENT The GRIK2 gene, encoding the GluK2 subunit of the kainate receptor, has been linked to several neuropsychiatric and neurodevelopmental disorders including obsessive compulsive disorder (OCD). Perseverative behaviors associated with OCD are known to result from pathophysiological changes in the striatum and kainate receptor knock-out mice have striatal-dependent phenotypes. However, the role of kainate receptors in striatal synapses is not known. We demonstrate that GluK2-containing kainate receptors regulate corticostriatal synapses by mobilizing endocannabinoids from direct pathway spiny projection neurons. Synaptic activation of GluK2 receptors during trains of synaptic input causes short-term synaptic depression, demonstrating a novel role for these receptors in regulating striatal circuits.

Identification of Driver Genes and Key Pathways of Ependymoma.

To identify ependymoma (EPN) driver genes and key pathways, and also to illuminate the connection between prognosis of EPN patients and expression levels of driver genes. The gene expression profiles of GSE50161, GSE66354, GSE74195, and GSE86574 were analyzed to figure out the differentially expressed genes (DEGs) between tissue of EPN and normal brain samples. To harvest the enrichment functions, pathways and hub genes, the Gene ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, and protein-protein interaction (PPI) network analysis were made. Subsquently, survival analysis was performed in 325 patients to illuminate the connection between prognosis of EPN and expression levels of hub genes. 20 functions and 10 pathways which were up- or downregulated between the EPN and normal samples were revealed applying GO and KEGG analysis. Mutual hub genes were TP53, TOP2A, CDK1, PCNA, and ACTA2. The pathways of Hedgehog and notch signaling, mismatch repair (MMR), and retrograde endocannabinoid were significantly abnormally regulated in EPN tissue. Survival analysis revealed favorable progression-free (PFS) and overall (OS) survival in EPN patients with low expression of TOP2A, CDK1, PCNA, and ACTA2 (p < 0.05). Patients with lower expression of TOP2A, CDK1, PCNA, and ACTA2 had a longer OS and PFS. The differential expressed genes identified and the key pathways selected in this research provided unprecedented and promising targets for diagnosis and treatment of EPN patients.

Acute Stress Suppresses Synaptic Inhibition and Increases Anxiety via Endocannabinoid Release in the Basolateral Amygdala

Stress and glucocorticoids stimulate the rapid mobilization of endocannabinoids in the basolateral amygdala (BLA). Cannabinoid receptors in the BLA contribute to anxiogenesis and fear-memory formation. We tested for rapid glucocorticoid-induced endocannabinoid regulation of synaptic inhibition in the rat BLA. Glucocorticoid application to amygdala slices elicited a rapid, nonreversible suppression of spontaneous, but not evoked, GABAergic synaptic currents in BLA principal neurons; the effect was also seen with a membrane-impermeant glucocorticoid, but not with intracellular glucocorticoid application, implicating a membrane-associated glucocorticoid receptor. The glucocorticoid suppression of GABA currents was not blocked by antagonists of nuclear corticosteroid receptors, or by inhibitors of gene transcription or protein synthesis, but was blocked by inhibiting postsynaptic G-protein activity, suggesting a postsynaptic nongenomic steroid signaling mechanism that stimulates the release of a retrograde messenger. The rapid glucocorticoid-induced suppression of inhibition was prevented by blocking CB1 receptors and 2-arachidonoylglycerol (2-AG) synthesis, and it was mimicked and occluded by CB1 receptor agonists, indicating it was mediated by the retrograde release of the endocannabinoid 2-AG. The rapid glucocorticoid effect in BLA neurons in vitro was occluded by prior in vivo acute stress-induced, or prior in vitro glucocorticoid-induced, release of endocannabinoid. Acute stress also caused an increase in anxiety-like behavior that was attenuated by blocking CB1 receptor activation and inhibiting 2-AG synthesis in the BLA. Together, these findings suggest that acute stress causes a long-lasting suppression of synaptic inhibition in BLA neurons via a membrane glucocorticoid receptor-induced release of 2-AG at GABA synapses, which contributes to stress-induced anxiogenesis. We provide a cellular mechanism in the basolateral amygdala (BLA) for the rapid stress regulation of anxiogenesis in rats. We demonstrate a nongenomic glucocorticoid induction of long-lasting suppression of synaptic inhibition that is mediated by retrograde endocannabinoid release at GABA synapses. The rapid glucocorticoid-induced endocannabinoid suppression of synaptic inhibition is initiated by a membrane-associated glucocorticoid receptor in BLA principal neurons. We show that acute stress increases anxiety-like behavior via an endocannabinoid-dependent mechanism centered in the BLA. The stress-induced endocannabinoid modulation of synaptic transmission in the BLA contributes, therefore, to the stress regulation of anxiety, and may play a role in anxiety disorders of the amygdala.

Endocannabinoids mediate the glucocorticoid‐induced inhibition of excitatory synaptic transmission to dorsal raphe serotonin neurons

Glucocorticoids play a critical role in the modulation of stress responses by controlling the function of the serotonin (5-HT) system. However, the precise effects of glucocorticoids on the excitability of dorsal raphe (DR) 5-HT neurons remain unknown. In this study, we investigated the effects of glucocorticoids on excitatory synaptic transmission to putative DR 5-HT neurons. We found that corticosterone or the synthetic glucocorticoid agonist dexamethasone rapidly suppressed glutamatergic synaptic transmission to DR 5-HT neurons by inhibiting glutamate release in the DR. This inhibitory effect was mimicked by membrane-impermeable glucocorticoids, indicating the involvement of membrane-located corticosteroid receptors. The glucocorticoid-induced inhibition of glutamatergic transmission was mediated by the activation of postsynaptic G-protein-coupled receptors and signalled by retrograde endocannabinoid (eCB) messengers. Examination of the downstream mechanisms revealed that glucocorticoids enhance eCB signalling via an inhibition of cyclooxygenase-2. Together, these findings unravel a novel mechanism by which glucocorticoids control the excitability of DR 5-HT neurons and provide new insight into the rapid effects of stress hormones on the function of the 5-HT system.

Action potential-triggered somatic exocytosis in mesencephalic trigeminal nucleus neurons in rat brain slices

The neurons in the mesencephalic trigeminal nucleus (MeV) play essential roles in proprioceptive sensation of the face and oral cavity. The somata of MeV neurons are generally assumed to carry out neuronal functions but not to play a direct role in synaptic transmission. Using whole-cell recording and membrane capacitance (C(m)) measurements, we found that the somata of MeV neurons underwent robust exocytosis (C(m) jumps) upon depolarization and with the normal firing of action potentials in brain slices. Both removing [Ca(2+)](o) and buffering [Ca(2+)](i) with BAPTA blocked this exocytosis, indicating that it was completely Ca(2+) dependent. In addition, an electron microscopic study showed synaptic-like vesicles approximated to the plasma membrane in somata. There was a single Ca(2+)-dependent releasable vesicle pool with a peak release rate of 1912 fF s(-1). Importantly, following depolarization-induced somatic exocytosis, GABA-mediated postsynaptic currents were transiently reduced by 31%, suggesting that the somatic vesicular release had a retrograde effect on afferent GABAergic transmission. These results provide strong evidence that the somata of MeV neurons undergo robust somatic secretion and may play a crucial role in bidirectional communication between somata and their synaptic inputs in the central nervous system.

Modulation of endocannabinoid-mediated long-lasting disinhibition of striatal output by cholinergic interneurons

The frequency and duration of glutamatergic inputs to the striatum are strong determinants of the net effect of retrograde endocannabinoid (eCB) signaling, and key factors in determining if long-term depression (LTD) has a net disinhibitory or inhibitory action in striatum. Low to moderate frequency stimulation in the dorsolateral striatum elevates eCB levels to an extent that primarily depresses transmitter release at inhibitory synapses, leading to a long-lasting disinhibition (DLL) of synaptic output. The aim of this study was to further characterize the basic features of endocannabinoid-mediated DLL of striatal output induced by moderate frequency stimulation (5 Hz, 60 s). DLL was inhibited in slices treated with the group 1 metabotropic glutamate receptor (mGluR) antagonists MPEP (40 μM) and CPCCOEt (40 μM), the dopamine D2 receptor antagonist sulpiride (5 μM), the L-type calcium channel blocker nifedipine (20 μM), the nicotinic receptor antagonist mecamylamine (10 μM), the muscarinic agonist oxotremorine sesquifumarate (10 μM), and strychnine (0.1 μM). Strychnine did not block DLL induced by WIN55,212-2 (250 nM), showing that glycine receptor-mediated modulation of eCB signaling occurs upstream from CB1R activation. Scopolamine (10 μM) restored DLL in strychnine-treated slices, suggesting that inhibition of glycine receptors on cholinergic interneurons could modulate eCB signaling by enhancing muscarinic receptor activation and reducing the opening of L-type calcium channels in response to depolarization. These data suggests that similar activation points are required for stimulation-induced DLL as for LTD at excitatory striatal synapses, and that cholinergic interneurons are key modulators of stimulation-induced eCB signaling in the striatum.

Retrograde Endocannabinoid Signaling Reduces Firing and GABA-ergic Synaptic Transmission to Gonadotropin-Releasing Hormone Neurons

Event Abstract Back to Event Retrograde Endocannabinoid Signaling Reduces Firing and GABA-ergic Synaptic Transmission to Gonadotropin-Releasing Hormone Neurons I. Farkas1*, I. Kalló1, L. Deli1, B. Vida1, E. Hrabovszky1, C. Fekete1, S. M. Moenter2, M. Watanabe3 and Z. Liposits1 1 Institute of Experimental Medicine, Hungarian Academy of Sciences, Department of Endocrine Neurobiology, Hungary 2 University of Virginia, Departments of Medicine and Cell Biology, United States 3 Hokkaido University School of Medicine, Department of Anatomy, Japan Cannabinoids suppress fertility via reducing hypothalamic GnRH output. GABAAR-mediated transmission is a major input to GnRH cells that can be excitatory. We hypothesized that cannabinoids act via inhibiting GABAergic input by a retrograde endocannabinoid signaling mechanism. Loose-patch studies of slices from adult male GnRH-GFP mice showed that bath application of WIN55,212 decreased GnRH neuron firing rate. This action was detectable in presence of kynurenic acid, but disappeared when bicuculline was also present, indicating GABAA-R involvement. In immunocytochemical experiments, CB1-IR axons formed contacts with GnRH neurons and a subset established symmetric synapses characteristic of GABA-ergic neurotransmission. Whole-cell patch-clamp studies revealed that WIN55,212 decreased the frequency of GABAA-R-mediated mPSCs, which was prevented with the AM251, indicating that activation of presynaptic CB1 inhibits GABA release. AM251 alone increased mPSC frequency, providing evidence that endocannabinoids tonically inhibit GABAA-R drive onto GnRH neurons. Increased mPSC frequency was absent when DAG-lipase was blocked intracellularly with THL, showing that tonic inhibition is caused by 2-AG production of GnRH neurons. When CdCl2 was applied to inhibit action potential-evoked calcium influx and endocannabinoid-mediated blockade of spontaneous vesicle fusion was blocked with AM251, GnRH neuron firing increased, revealing an endogenous endocannabinoid brake on GnRH neuron firing. Keywords: Neuroendocrinology, Neuroscience Conference: 13th Conference of the Hungarian Neuroscience Society (MITT), Budapest, Hungary, 20 Jan - 22 Jan, 2011. Presentation Type: Abstract Topic: Neuroendocrinology Citation: Farkas I, Kalló I, Deli L, Vida B, Hrabovszky E, Fekete C, Moenter SM, Watanabe M and Liposits Z (2011). Retrograde Endocannabinoid Signaling Reduces Firing and GABA-ergic Synaptic Transmission to Gonadotropin-Releasing Hormone Neurons. Front. Neurosci. Conference Abstract: 13th Conference of the Hungarian Neuroscience Society (MITT). doi: 10.3389/conf.fnins.2011.84.00116 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 03 Mar 2011; Published Online: 23 Mar 2011. * Correspondence: Dr. I. Farkas, Institute of Experimental Medicine, Hungarian Academy of Sciences, Department of Endocrine Neurobiology, Budapest, Hungary, b.farkas@richter.hu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers I. Farkas I. Kalló L. Deli B. Vida E. Hrabovszky C. Fekete S. M Moenter M. Watanabe Z. Liposits Google I. Farkas I. Kalló L. Deli B. Vida E. Hrabovszky C. Fekete S. M Moenter M. Watanabe Z. Liposits Google Scholar I. Farkas I. Kalló L. Deli B. Vida E. Hrabovszky C. Fekete S. M Moenter M. Watanabe Z. Liposits PubMed I. Farkas I. Kalló L. Deli B. Vida E. Hrabovszky C. Fekete S. M Moenter M. Watanabe Z. Liposits Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Loss of Retrograde Endocannabinoid Signaling and Reduced Adult Neurogenesis in Diacylglycerol Lipase Knock-out Mice

Endocannabinoids (eCBs) function as retrograde signaling molecules at synapses throughout the brain, regulate axonal growth and guidance during development, and drive adult neurogenesis. There remains a lack of genetic evidence as to the identity of the enzyme(s) responsible for the synthesis of eCBs in the brain. Diacylglycerol lipase-alpha (DAGLalpha) and -beta (DAGLbeta) synthesize 2-arachidonoyl-glycerol (2-AG), the most abundant eCB in the brain. However, their respective contribution to this and to eCB signaling has not been tested. In the present study, we show approximately 80% reductions in 2-AG levels in the brain and spinal cord in DAGLalpha(-/-) mice and a 50% reduction in the brain in DAGLbeta(-/-) mice. In contrast, DAGLbeta plays a more important role than DAGLalpha in regulating 2-AG levels in the liver, with a 90% reduction seen in DAGLbeta(-/-) mice. Levels of arachidonic acid decrease in parallel with 2-AG, suggesting that DAGL activity controls the steady-state levels of both lipids. In the hippocampus, the postsynaptic release of an eCB results in the transient suppression of GABA-mediated transmission at inhibitory synapses; we now show that this form of synaptic plasticity is completely lost in DAGLalpha(-/-) animals and relatively unaffected in DAGLbeta(-/-) animals. Finally, we show that the control of adult neurogenesis in the hippocampus and subventricular zone is compromised in the DAGLalpha(-/-) and/or DAGLbeta(-/-) mice. These findings provide the first evidence that DAGLalpha is the major biosynthetic enzyme for 2-AG in the nervous system and reveal an essential role for this enzyme in regulating retrograde synaptic plasticity and adult neurogenesis.

Synaptic organization of retrograde 2-arachidonoylglycerol signaling in the dorsolateral periaqueductal grey matter

Event Abstract Back to Event Synaptic organization of retrograde 2-arachidonoylglycerol signaling in the dorsolateral periaqueductal grey matter Rita Nyilas1*, Laura C. Gregg2, Jessica M. Spradley2, Ken Mackie3, Andrea G. Hohmann2 and István Katona1 1 Hungarian Academy of Sciences, Institute of Experimental Medicine, Hungary 2 University of Georgia, United States 3 Indiana University, United States The striking antinociceptive effect of cannabinoid receptor agonists in acute nociception and chronic pain states is well-documented. 2-arachidonoylglycerol (2-AG), an endogenous ligand for both CB1 and CB2 cannabinoid receptors and a candidate retrograde synaptic endocannabinoid in the brain, has been implicated in the physiological regulation of nociception. However, the molecular machinery of synaptic 2-AG signaling involved has not been identified in the periaqueductal grey matter (PAG), a key midbrain area in the descending control of pain. To uncover the molecular architecture of 2-AG synthesis and identify sites of 2-AG action, we examined the detailed anatomical distribution of diacylglycerol lipase-α (DGL-α), metabotropic glutamate receptor 5 (mGluR5) and the CB1 cannabinoid receptor in the rodent dorsolateral (dl) PAG. Using peroxidase-based immunocytochemistry, dense distribution of DGL-α enzyme and CB1 receptor was revealed at the light microscopic level. Immunogold labeling followed by high-resolution electron microscopy showed that DGL-α, the main biosynthetic enzyme of 2-AG, was located in a remarkable postsynaptic position and co-localized with metabotropic glutamate receptor 5 (mGluR5), an upstream activator of 2-AG biosynthesis, while CB1 was found presynaptically on axon terminals. This striking positioning of DGL-α and CB1 were found at both excitatory and inhibitory synapses of the dl PAG. These findings imply a key role of the retrograde 2-AG pathway, present in dl PAG neuronal synapses, in the activity-dependent regulation of nociception. Conference: IBRO International Workshop 2010, Pécs, Hungary, 21 Jan - 23 Jan, 2010. Presentation Type: Poster Presentation Topic: Cellular neuroscience Citation: Nyilas R, Gregg LC, Spradley JM, Mackie K, Hohmann AG and Katona I (2010). Synaptic organization of retrograde 2-arachidonoylglycerol signaling in the dorsolateral periaqueductal grey matter. Front. Neurosci. Conference Abstract: IBRO International Workshop 2010. doi: 10.3389/conf.fnins.2010.10.00112 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 23 Apr 2010; Published Online: 23 Apr 2010. * Correspondence: Rita Nyilas, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary, nyilasr@koki.hu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Rita Nyilas Laura C Gregg Jessica M Spradley Ken Mackie Andrea G Hohmann István Katona Google Rita Nyilas Laura C Gregg Jessica M Spradley Ken Mackie Andrea G Hohmann István Katona Google Scholar Rita Nyilas Laura C Gregg Jessica M Spradley Ken Mackie Andrea G Hohmann István Katona PubMed Rita Nyilas Laura C Gregg Jessica M Spradley Ken Mackie Andrea G Hohmann István Katona Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Developmental Alteration of Endocannabinoid Retrograde Signaling in the Hippocampus

Endocannabinoids are lipid derivatives that mediate paracrine and juxtacrine signaling between cells. In the hippocampal CA1 region, a retrograde endocannabinoid signal suppresses GABA release by acting on presynaptic cannabinoid receptor-1 (CB1) and can be functionally manifested as depolarization-induced suppression of inhibition (DSI). In the present study, whole cell patch-clamp recordings in hippocampal slices were made to examine DSI in rats from P7-P21. Robust DSI develops in rat hippocampus at postnatal ages greater than two weeks, but only modest DSI is observed in P7-9 rat. DSI in neonatal rats can be enhanced by activation of group I metabotropic glutamate receptors (mGluRs) or muscarinic acetylcholine receptors in those neonatal rats. The DSI is also enhanced by sustained low-frequency (1 Hz) stimulation (5 min). This stimulus-enhanced DSI was prevented in the presence of 6-methyl-2-(phenylethynyl)-pyridine (10 microM), a group I mGluR antagonist. WIN55212-2, a synthetic CB1 agonist, produced a similar level of inhibition of GABAergic synaptic transmission at different postnatal time points. Therefore postsynaptic mechanisms appear to be mainly responsible for developmental changes in DSI, although presynaptic mechanisms cannot be ruled out entirely. We have also obtained evidence that tonic endocannabinoid release suppresses GABAergic transmission in the mature but not the neonatal hippocampus. The differential DSI magnitude at different stages of maturation could alter synaptic plasticity and learning and memory during hippocampal development.

S17.4 Molecular reconstruction of endocannibinoid production, mobilization, and signaling in single rat sympathetic neurons

Retrograde endocannabinoid (eCB) signaling underlies numerous forms of short- and long-term plasticity in the central nervous system [1]. This form of synaptic modulation begins with the metabolic formation of an eCB agonist, e.g., 2-arachidonylglycerol (2-AG), in the postsynaptic neuron. Subsequently, 2-AG traverses the plasma membrane, crosses the synaptic cleft, and interacts with CB1 cannabinoid receptors (CB1R) on the presynaptic nerve terminal. Activation of CB1R depresses synaptic release via inhibition of voltage-gated Ca2+ channels and perhaps other mechanisms [2].

Regulation of IPSP Theta Rhythm by Muscarinic Receptors and Endocannabinoids in Hippocampus

Theta rhythms are behaviorally relevant electrical oscillations in the mammalian brain, particularly the hippocampus. In many cases, theta oscillations are shaped by inhibitory postsynaptic potentials (IPSPs) that are driven by glutamatergic and/or cholinergic inputs. Here we show that hippocampal theta rhythm IPSPs induced in the CA1 region by muscarinic acetylcholine receptors independent of all glutamate receptors can be briefly interrupted by action potential-induced, retrograde endocannabinoid release. Theta IPSPs can be recorded in CA1 pyramidal cell somata surgically isolated from CA3, subiculum, and even from their own apical dendrites. These results suggest that perisomatic-targeting interneurons whose output is subject to inhibition by endocannabinoids are the likely source of theta IPSPs. Interneurons having these properties include the cholecystokinin-containing cells. Simultaneous recordings from pyramidal cell pairs reveal synchronous theta-frequency IPSPs in neighboring pyramidal cells, suggesting that these IPSPs may help entrain or modulate small groups of pyramidal cells.