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      Oral Ultramicronized Palmitoylethanolamide: Plasma and Tissue Levels and Spinal Anti-hyperalgesic Effect

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          Palmitoylethanolamide (PEA) is a pleiotropic lipid mediator with established anti-inflammatory and anti-hyperalgesic activity. Ultramicronized PEA (PEA-um) has superior oral efficacy compared to naïve (non-micronized) PEA. The aim of the present study was two-fold: (1) to evaluate whether oral PEA-um has greater absorbability compared to naïve PEA, and its ability to reach peripheral and central tissues under healthy and local inflammatory conditions (carrageenan paw edema); (2) to better characterize the molecular pathways involved in PEA-um action, particularly at the spinal level. Rats were dosed with 30 mg/kg of [ 13C] 4-PEA-um or naïve [ 13C] 4-PEA by oral gavage, and [ 13C] 4-PEA levels quantified, as a function of time, by liquid chromatography/atmospheric pressure chemical ionization/mass spectrometry. Overall plasma levels were higher in both healthy and carrageenan-injected rats administered [ 13C] 4-PEA-um as compared to those receiving naïve [ 13C] 4-PEA, indicating the greater absorbability of PEA-um. Furthermore, carrageenan injection markedly favored an increase in levels of [ 13C] 4-PEA in plasma, paw and spinal cord. Oral treatment of carrageenan-injected rats with PEA-um (10 mg/kg) confirmed beneficial peripheral effects on paw inflammation, thermal hyperalgesia and tissue damage. Notably, PEA-um down-regulated distinct spinal inflammatory and oxidative pathways. These last findings instruct on spinal mechanisms involved in the anti-hyperalgesic effect of PEA-um in inflammatory pain.

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          The endogenous cannabinoid system controls extinction of aversive memories.

          Acquisition and storage of aversive memories is one of the basic principles of central nervous systems throughout the animal kingdom. In the absence of reinforcement, the resulting behavioural response will gradually diminish to be finally extinct. Despite the importance of extinction, its cellular mechanisms are largely unknown. The cannabinoid receptor 1 (CB1) and endocannabinoids are present in memory-related brain areas and modulate memory. Here we show that the endogenous cannabinoid system has a central function in extinction of aversive memories. CB1-deficient mice showed strongly impaired short-term and long-term extinction in auditory fear-conditioning tests, with unaffected memory acquisition and consolidation. Treatment of wild-type mice with the CB1 antagonist SR141716A mimicked the phenotype of CB1-deficient mice, revealing that CB1 is required at the moment of memory extinction. Consistently, tone presentation during extinction trials resulted in elevated levels of endocannabinoids in the basolateral amygdala complex, a region known to control extinction of aversive memories. In the basolateral amygdala, endocannabinoids and CB1 were crucially involved in long-term depression of GABA (gamma-aminobutyric acid)-mediated inhibitory currents. We propose that endocannabinoids facilitate extinction of aversive memories through their selective inhibitory effects on local inhibitory networks in the amygdala.
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            Molecular characterization of an enzyme that degrades neuromodulatory fatty-acid amides.

            Endogenous neuromodulatory molecules are commonly coupled to specific metabolic enzymes to ensure rapid signal inactivation. Thus, acetylcholine is hydrolysed by acetylcholine esterase and tryptamine neurotransmitters like serotonin are degraded by monoamine oxidases. Previously, we reported the structure and sleep-inducing properties of cis-9-octadecenamide, a lipid isolated from the cerebrospinal fluid of sleep-deprived cats. cis-9-Octadecenamide, or oleamide, has since been shown to affect serotonergic systems and block gap-junction communication in glial cells (our unpublished results). We also identified a membrane-bound enzyme activity that hydrolyses oleamide to its inactive acid, oleic acid. We now report the mechanism-based isolation, cloning and expression of this enzyme activity, originally named oleamide hydrolase, from rat liver plasma membranes. We also show that oleamide hydrolase converts anandamide, a fatty-acid amide identified as the endogenous ligand for the cannabinoid receptor, to arachidonic acid, indicating that oleamide hydrolase may serve as the general inactivating enzyme for a growing family of bioactive signalling molecules, the fatty-acid amides. Therefore we will hereafter refer to oleamide hydrolase as fatty-acid amide hydrolase, in recognition of the plurality of fatty-acid amides that the enzyme can accept as substrates.
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              I kappa B: a specific inhibitor of the NF-kappa B transcription factor.

              In cells that do not express immunoglobulin kappa light chain genes, the kappa enhancer binding protein NF-kappa B is found in cytosolic fractions and exhibits DNA binding activity only in the presence of a dissociating agent such as sodium deoxycholate. The dependence on deoxycholate is shown to result from association of NF-kappa B with a 60- to 70-kilodalton inhibitory protein (I kappa B). The fractionated inhibitor can inactivate NF-kappa B from various sources--including the nuclei of phorbol ester-treated cells--in a specific, saturable, and reversible manner. The cytoplasmic localization of the complex of NF-kappa B and I kappa B was supported by enucleation experiments. An active phorbol ester must therefore, presumably by activation of protein kinase C, cause dissociation of a cytoplasmic complex of NF-kappa B and I kappa B by modifying I kappa B. this releases active NF-kappa B which can translocate into the nucleus to activate target enhancers. The data show the existence of a phorbol ester-responsive regulatory protein that acts by controlling the DNA binding activity and subcellular localization of a transcription factor.

                Author and article information

                Front Pharmacol
                Front Pharmacol
                Front. Pharmacol.
                Frontiers in Pharmacology
                Frontiers Media S.A.
                20 March 2018
                : 9
                1Endocannabinoid Research Group, Institute of Biomolecular Chemistry, CNR , Napoli, Italy
                2Epitech Group SpA , Padova, Italy
                3Department of Chemical, Biological, Pharmaceutical and Environmental Science University of Messina , Messina, Italy
                4Innovative Statistical Research SRL , Padova, Italy
                Author notes

                Edited by: Annalisa Bruno, Università degli Studi G. d'Annunzio Chieti e Pescara, Italy

                Reviewed by: Andrea Moriondo, University of Insubria, Italy; Caterina Scuderi, Sapienza Università di Roma, Italy

                *Correspondence: Stefania Petrosino spetrosino@ 123456icb.cnr.it

                This article was submitted to Inflammation Pharmacology, a section of the journal Frontiers in Pharmacology

                †These authors have contributed equally to this work.

                Copyright © 2018 Petrosino, Cordaro, Verde, Schiano Moriello, Marcolongo, Schievano, Siracusa, Piscitelli, Peritore, Crupi, Impellizzeri, Esposito, Cuzzocrea and Di Marzo.

                This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

                Page count
                Figures: 11, Tables: 0, Equations: 0, References: 106, Pages: 17, Words: 11836
                Original Research


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