anandamide and Nerve-Degeneration

Acylethanolamides are formed in the brain "on demand" from membrane phospholipids called N-acylated phosphatidylethanolamines. The acylethanolamides are signaling molecules of lipid nature, and this lipofilicity suggests an autocrine function. The acylethanolamides include palmitoylethanolamide (PEA), oleoylethanolamide (OEA), stearoylethanolamide (SEA), and several other quantitative minor species including anandamide (= arachidonoylethanolamide). PEA and OEA can activate several different receptors and inhibit some ion channels, e.g., PPARalpha, vanilloid receptor, K(+) channels (Kv4.3, Kv1.5), and OEA can activate GPR119 and inhibit ceramidases. Targets for SEA are less clear, but it has some cannabimimetic actions in rats in vivo. All acylethanolamides accumulate during neuronal injury, and injected OEA has neuroprotective effects, and PEA has anti-inflammatory effects as studied in the peripheral system. Several of the pharmacological effects seem to be mediated via activation of PPARalpha. Recently, injected OEA has been found to consolidate memories in rats. Inhibitors of the acylethanolamide-degrading enzyme FAAH can increase levels of all acylethanolamides including annandamide, and some of the pharmacological effects caused by these inhibitors may be explained by increased cerebral levels of OEA and PEA, e.g., suppression of nicotine-induced activation of dopamine neurons. Furthermore, through activation of PPARalpha, OEA and PEA may stimulate neurosteroid synthesis, thereby modulating several biological functions mediated by GABA(A) receptors. The existence of acylethanolamides in the mammalian brain has been known for decades, but it is first within the last few years that the putative biological functions of the three most abundant acylethanolamides species are starting to emerge.

Topics: Amides; Animals; Arachidonic Acids; Brain; Cytoprotection; Endocannabinoids; Ethanolamines; Humans; Nerve Degeneration; Neurons; Oleic Acids; Palmitic Acids; Polyunsaturated Alkamides; Receptors, Cannabinoid

We studied the prolonged action of kainic acid on glutamatergic neurons in the dorsal hippocampus and the endocannabinoid-dependent protection against neurodegeneration. The pyramidal neurons of the CA3 field of the hippocampus, as well as granular and mossy cells of the dentate gyrus were examined. Light and electron microscopy revealed substantial damage to the components of the protein-synthesizing (rough endoplasmic reticulum, Golgi apparatus, and polyribosomes) and catabolic (lysosomes, autophagosomes, multivesicular structures, and lipofuscin formations) systems in all cells. Pyramidal and mossy neurons die mainly by the necrotic pathway. The death of granular cells occurred through both apoptosis and necrosis. The most vulnerable cells are mossy neurons located in the hilus. Activation of the endocannabinoid system induced by intracerebral injection of URB597, an inhibitor of degradation of endocannabinoid anandamide, protected the normal structure of the hippocampus and prevented neuronal damage and death induced by KA.

Topics: Animals; Arachidonic Acids; Autophagosomes; Benzamides; CA3 Region, Hippocampal; Carbamates; Dentate Gyrus; Endocannabinoids; Endoplasmic Reticulum; Excitatory Amino Acid Agonists; Golgi Apparatus; Kainic Acid; Lysosomes; Male; Microscopy, Electron; Necrosis; Nerve Degeneration; Polyunsaturated Alkamides; Pyramidal Cells; Rats; Rats, Wistar; Status Epilepticus

The consumption of ethanol by pregnant women may cause neurological abnormalities, affecting learning and memory processes in children, and are collectively described as fetal alcohol spectrum disorders. However, the molecular mechanisms underlying these changes are still poorly understood. In our previous studies, we found that ethanol treatment of postnatal day 7 (P7) mice significantly enhances the anandamide levels but not the 2-arachidonylglycerol (2-AG) levels and induces widespread neurodegeneration, but the reason for the lack of significant effects of ethanol on the 2-AG level is unknown. In this study, we examined developmental changes in diacylglycerol lipase-α, β (DAGL-α and β) and monoacylglycerol lipase (MAGL). We found that the levels of these proteins were significantly higher in adult brains compared to those detected early in brain development. Next, we examined the influence of P7 ethanol treatment on these enzymes, finding that it differentially altered the DAGL-α protein and mRNA levels but consistently enhanced those of the DAGL-β. Interestingly, the ethanol treatment enhanced MAGL protein and mRNA levels. Inhibition of MAGL with KML29 failed to induce neurodegeneration in P7 mice. Collectively, these findings suggest that ethanol significantly activates DAGL-β and MAGL in the neonatal brain, resulting in no net change in 2-AG levels.

Topics: Animals; Animals, Newborn; Arachidonic Acids; Brain; Central Nervous System Depressants; Chromatography, Liquid; Endocannabinoids; Ethanol; Glycerides; Immunoblotting; Lipoprotein Lipase; Mass Spectrometry; Mice; Mice, Inbred C57BL; Monoacylglycerol Lipases; Nerve Degeneration; Polyunsaturated Alkamides; Real-Time Polymerase Chain Reaction

The transient exposure of immature rodents to ethanol during postnatal day 7 (P7), which is comparable with the third trimester in human pregnancy, induces synaptic dysfunctions. However, the molecular mechanisms underlying these dysfunctions are still poorly understood. Although the endocannabinoid system has been shown to be an important modulator of ethanol sensitivity in adult mice, its potential role in synaptic dysfunctions in mice exposed to ethanol during early brain development is not examined. In this study, we investigated the potential role of endocannabinoids and the cannabinoid receptor type 1 (CB1R) in neonatal neurodegeneration and adult synaptic dysfunctions in mice exposed to ethanol at P7. Ethanol treatment at P7, which induces neurodegeneration, increased anandamide (AEA) but not 2-arachidonylglycerol biosynthesis and CB1R protein expression in the hippocampus and cortex, two brain areas that are important for memory formation and storage, respectively. N-Arachidonoyl phosphatidylethanolamine-phospholipase D (NAPE-PLD), glycerophosphodiesterase (GDE1), and CB1R protein expression were enhanced by transcriptional activation of the genes encoding NAPE-PLD, GDE1, and CB1R proteins, respectively. In addition, ethanol inhibited ERK1/2 and AKT phosphorylation. The blockade of CB1Rs before ethanol treatment at P7 relieved ERK1/2 but not AKT phosphorylation and prevented neurodegeneration. CB1R knock-out mice exhibited no ethanol-induced neurodegeneration and inhibition of ERK1/2 phosphorylation. The protective effects of CB1R blockade through pharmacological or genetic deletion resulted in normal adult synaptic plasticity and novel object recognition memory in mice exposed to ethanol at P7. The AEA/CB1R/pERK1/2 signaling pathway may be directly responsible for the synaptic and memory deficits associated with fetal alcohol spectrum disorders.

Topics: Animals; Animals, Newborn; Arachidonic Acids; Brain; Cannabinoid Receptor Antagonists; Endocannabinoids; Ethanol; Female; Gene Expression Regulation, Developmental; Glycerides; Male; Memory Disorders; Mice; Mice, Inbred C57BL; Mice, Knockout; Nerve Degeneration; Nerve Tissue Proteins; Neuronal Plasticity; Neuroprotective Agents; Phospholipase D; Phosphoric Diester Hydrolases; Phosphorylation; Piperidines; Polyunsaturated Alkamides; Pyrazoles; Receptor, Cannabinoid, CB1; Rimonabant; Signal Transduction; Synapses

Cannabinoid CB1 receptors (CB1Rs) regulate the neurodegenerative damage of experimental autoimmune encephalomyelitis (EAE) and of multiple sclerosis (MS). The mechanism by which CB1R stimulation exerts protective effects is still unclear. Here we show that pharmacological activation of CB1Rs dampens the tumor necrosis factor α (TNFα)-mediated potentiation of striatal spontaneous glutamate-mediated excitatory postsynaptic currents (EPSCs), which is believed to cogently contribute to the inflammation-induced neurodegenerative damage observed in EAE mice. Furthermore, mice lacking CB1Rs showed a more severe clinical course and, in parallel, exacerbated alterations of sEPSC duration after induction of EAE, indicating that endogenous cannabinoids activate CB1Rs and mitigate the synaptotoxic action of TNFα in EAE. Consistently, we found that mice lacking the fatty acid amide hydrolase (FAAH), and thus expressing abnormally high brain levels of the endocannabinoid anandamide, developed a less severe EAE associated with preserved TNFα-induced sEPSC alterations. CB1Rs are important modulators of EAE pathophysiology, and might play a mechanistic role in the neurodegenerative damage of MS patients.

Topics: 6-Cyano-7-nitroquinoxaline-2,3-dione; Amidohydrolases; Animals; Arachidonic Acids; Cannabinoid Receptor Modulators; Corpus Striatum; Dizocilpine Maleate; Dronabinol; Encephalomyelitis, Autoimmune, Experimental; Endocannabinoids; Etanercept; Excitatory Postsynaptic Potentials; Female; Glutamic Acid; Immunoglobulin G; Mice; Mice, Inbred C57BL; Mice, Knockout; Nerve Degeneration; Neurons; Polyunsaturated Alkamides; Receptor, Cannabinoid, CB1; Receptors, AMPA; Receptors, N-Methyl-D-Aspartate; Receptors, Tumor Necrosis Factor; Tumor Necrosis Factor-alpha

We provide evidence that TWIK-related acid-sensitive potassium channel 1 (TASK1), a member of the family of two-pore domain potassium channels relevant for setting the resting membrane potential and balancing neuronal excitability that is expressed on T cells and neurons, is a key modulator of T cell immunity and neurodegeneration in autoimmune central nervous system inflammation. After induction of experimental autoimmune encephalomyelitis, an experimental model mimicking multiple sclerosis, TASK1(-/-) mice showed a significantly reduced clinical severity and markedly reduced axonal degeneration compared with wild-type controls. T cells from TASK1(-/-) mice displayed impaired T cell proliferation and cytokine production, while the immune repertoire is otherwise normal. In addition to these effects on systemic T cell responses, TASK1 exhibits an independent neuroprotective effect which was demonstrated using both a model of acutely prepared brain slices cocultured with activated T cells as well as in vitro cultivation experiments with isolated optic nerves. Anandamide, an endogenous cannabinoid and inhibitor of TASK channels, reduced outward currents and inhibited effector functions of T cells (IFN-gamma production and proliferation); an effect completely abrogated in TASK1(-/-) mice. Accordingly, preventive blockade of TASK1 significantly ameliorated experimental autoimmune encephalomyelitis after immunization. Therapeutic application of anandamide significantly reduced disease severity and was capable of lowering progressive loss of brain parenchymal volume as assessed by magnetic resonance imaging. These data support the identification and characterization of TASK1 as potential molecular target for the therapy of inflammatory and degenerative central nervous system disorders.

Topics: Animals; Arachidonic Acids; Axons; Cells, Cultured; Coculture Techniques; Disease Progression; Encephalomyelitis, Autoimmune, Experimental; Endocannabinoids; Female; Immunophenotyping; Lymphocyte Activation; Mice; Mice, Inbred C57BL; Mice, Knockout; Multiple Sclerosis; Nerve Degeneration; Nerve Tissue Proteins; Polyunsaturated Alkamides; Potassium Channel Blockers; Potassium Channels, Tandem Pore Domain; Spinal Cord; Spleen; T-Lymphocyte Subsets; Tissue Culture Techniques

Cannabinoids (CBs) are attributed neuroprotective effects in vivo. Here, we determined the neuroprotective potential of CBs during neuronal damage in excitotoxically lesioned organotypic hippocampal slice cultures (OHSCs). OHSCs are the best characterized in vitro model to investigate the function of microglial cells in neuronal damage since blood-borne monocytes and T-lymphocytes are absent and microglial cells represent the only immunocompetent cell type. Excitotoxic neuronal damage was induced by NMDA (50 microM) application for 4 h. Neuroprotective properties of 9-carboxy-11-nor-delta-9-tetrahydrocannabinol (THC), N-arachidonoylethanolamide (AEA) or 2-arachidonoylglycerol (2-AG) in different concentrations were determined after co-application with NMDA by counting degenerating neurons identified by propidium iodide labeling (PI(+)) and microglial cells labeled by isolectin B(4) (IB(4)(+)). All three CBs used significantly decreased the number of IB(4)(+) microglial cells in the dentate gyrus but the number of PI(+) neurons was reduced only after 2-AG treatment. Application of AM630, antagonizing CB2 receptors highly expressed by activated microglial cells, did not counteract neuroprotective effects of 2-AG, but affected THC-mediated reduction of IB(4)(+) microglial cells. Our results indicate that (1) only 2-AG exerts neuroprotective effects in OHSCs; (2) reduction of IB(4)(+) microglial cells is not a neuroprotective event per se and involves other CB receptors than the CB2 receptor; (3) the discrepancy in the neuroprotective effects of CBs observed in vivo and in our in vitro model system may underline the functional relevance of invading monocytes and T-lymphocytes that are absent in OHSCs.

Topics: Animals; Animals, Newborn; Arachidonic Acids; Brain; Brain Damage, Chronic; Cannabinoids; Cell Count; Disease Models, Animal; Dronabinol; Endocannabinoids; Gliosis; Glycerides; Microglia; N-Methylaspartate; Nerve Degeneration; Neurons; Neuroprotective Agents; Neurotoxins; Organ Culture Techniques; Plant Lectins; Polyunsaturated Alkamides; Rats; Rats, Wistar; Receptor, Cannabinoid, CB2; Treatment Outcome

Type 1 vanilloid receptors (VR1) have been identified recently in the brain, in which they serve as yet primarily undetermined purposes. The endocannabinoid anandamide (AEA) and some of its oxidative metabolites are ligands for VR1, and AEA has been shown to afford protection against ouabain-induced in vivo excitotoxicity, in a manner that is only in part dependent on the type 1 cannabinoid (CB1) receptor. In the present study, we assessed whether VR1 is involved in neuroprotection by AEA and by arvanil, a hydrolysis-stable AEA analog that is a ligand for both VR1 and CB1. Furthermore, we assessed the putative involvement of lipoxygenase metabolites of AEA in conveying neuroprotection. Using HPLC and gas chromatography/mass spectroscopy, we demonstrated that rat brain and blood cells converted AEA into 12-hydroxy-N-arachidoylethanolamine (12-HAEA) and 15-hydroxy-N-arachidonoylethanolamine (15-HAEA) and that this conversion was blocked by addition of the lipoxygenase inhibitor nordihydroguaiaretic acid. Using magnetic resonance imaging we show the following: (1) pretreatment with the reduced 12-lipoxygenase metabolite of AEA, 12-HAEA, attenuated cytotoxic edema formation in a CB1 receptor-independent manner in the acute phase after intracranial injection of the Na+/K+-ATPase inhibitor ouabain; (2) the reduced 15-lipoxygenase metabolite, 15-HAEA, enhanced the neuroprotective effect of AEA in the acute phase; (3) modulation of VR1, as tested using arvanil, the VR1 agonist capsaicin, and the antagonist capsazepine, leads to neuroprotective effects in this model, and arvanil is a potent neuroprotectant, acting at both CB1 and VR1; and (4) the in vivo neuroprotective effects of AEA are mediated by CB1 but not by lipoxygenase metabolites or VR1.

Topics: Animals; Animals, Newborn; Arachidonic Acids; Blood Cells; Brain; Brain Chemistry; Brain Mapping; Cannabinoid Receptor Modulators; Cannabinoids; Capsaicin; Endocannabinoids; Ethanolamines; Fatty Acids, Unsaturated; Lipoxygenase; Male; Masoprocol; Nerve Degeneration; Neuroprotective Agents; Ouabain; Polyunsaturated Alkamides; Rats; Rats, Wistar; Receptors, Drug

Endogenous cannabinoid receptor ligands (endocannabinoids) may rescue neurons from glutamate excitotoxicity. As these substances also accumulate in cultured immature neurons following neuronal damage, elevated endocannabinoid concentrations may be interpreted as a putative neuroprotective response. However, it is not known how glutamatergic insults affect in vivo endocannabinoid homeostasis, i.e. N-arachidonoylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG), as well as other constituents of their lipid families, N-acylethanolamines (NAEs) and 2-monoacylglycerols (2-MAGs), respectively. Here we employed three in vivo neonatal rat models characterized by widespread neurodegeneration as a consequence of altered glutamatergic neurotransmission and assessed changes in endocannabinoid homeostasis. A 46-fold increase of cortical NAE concentrations (anandamide, 13-fold) was noted 24 h after intracerebral NMDA injection, while less severe insults triggered by mild concussive head trauma or NMDA receptor blockade produced a less pronounced NAE accumulation. By contrast, levels of 2-AG and other 2-MAGs were virtually unaffected by the insults employed, rendering it likely that key enzymes in biosynthetic pathways of the two different endocannabinoid structures are not equally associated to intracellular events that cause neuronal damage in vivo. Analysis of cannabinoid CB(1) receptor mRNA expression and binding capacity revealed that cortical subfields exhibited an up-regulation of these parameters following mild concussive head trauma and exposure to NMDA receptor blockade. This may suggest that mild to moderate brain injury may trigger elevated endocannabinoid activity via concomitant increase of anandamide levels, but not 2-AG, and CB(1) receptor density.

Topics: Animals; Arachidonic Acids; Brain Concussion; Cannabinoid Receptor Modulators; Cerebral Cortex; Corpus Striatum; Craniocerebral Trauma; Dizocilpine Maleate; Endocannabinoids; Ethanolamines; Excitatory Amino Acid Agonists; Excitatory Amino Acid Antagonists; Glycerides; Male; N-Methylaspartate; Nerve Degeneration; Polyunsaturated Alkamides; Rats; Rats, Sprague-Dawley; Receptors, Cannabinoid; Receptors, Drug; RNA, Messenger