title: N-arachidonoyl-L-serine is neuroprotective after traumatic brain injury by reducing apoptosis.
abstract: N-arachidonoyl-L-serine (AraS) is a brain component structurally related to the endocannabinoid family. We investigated the neuroprotective effects of AraS following closed head injury induced by weight drop onto the exposed fronto-parietal skull and the mechanisms involved. A single injection of AraS following injury led to a significant improvement in functional outcome, and to reduced edema and lesion volume compared with vehicle. Specific antagonists to CB2 receptors, transient receptor potential vanilloid 1 (TRPV1) or large conductance calcium-activated potassium (BK) channels reversed these effects. Specific binding assays did not indicate binding of AraS to the GPR55 cannabinoid receptor. N-arachidonoyl-L-serine blocked the attenuation in phosphorylated extracellular-signal-regulated kinase 1/2 (ERK) levels and led to an increase in pAkt in both the ipsilateral and contralateral cortices. Increased levels of the prosurvival factor Bcl-xL were evident 24 hours after injury in AraS-treated mice, followed by a 30% reduction in caspase-3 activity, measured 3 days after injury. Treatment with a CB2 antagonist, but not with a CB1 antagonist, reversed this effect. Our results suggest that administration of AraS leads to neuroprotection via ERK and Akt phosphorylation and induction of their downstream antiapoptotic pathways. These protective effects are related mostly to indirect signaling via the CB2R and TRPV1 channels but not through CB1 or GPR55 receptors.
authors.affiliation: Department of Pharmacology, Institute of Drug Research, Medical Faculty, Hebrew University of Jerusalem, Jerusalem, Israel.
authors.forename: Ayelet
authors.initials: A
authors.lastname: Cohen-Yeshurun
authors.forename: Victoria
authors.initials: V
authors.lastname: Trembovler
authors.forename: Alexander
authors.initials: A
authors.lastname: Alexandrovich
authors.forename: Erik
authors.initials: E
authors.lastname: Ryberg
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Greasley
authors.forename: Raphael
authors.initials: R
authors.lastname: Mechoulam
authors.forename: Esther
authors.initials: E
authors.lastname: Shohami
authors.forename: Ronen R
authors.initials: RR
authors.lastname: Leker
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001095:Arachidonic Acids / Q000494:pharmacology* / Q000627:therapeutic use; D001930:Brain Injuries / Q000188:drug therapy* / Q000473:pathology; D008297:Male; D051379:Mice; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D018696:Neuroprotective Agents; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D043885:Receptor, Cannabinoid, CB2 / Q000378:metabolism; D020127:Recovery of Function; D012694:Serine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D050916:TRPV Cation Channels / Q000378:metabolism
chemical_list: D001095:Arachidonic Acids; C509235:N-arachidonoyl L-serine; D018696:Neuroprotective Agents; D043885:Receptor, Cannabinoid, CB2; D050916:TRPV Cation Channels; C494484:TRPV1 receptor; D012694:Serine; D051057:Proto-Oncogene Proteins c-akt; D048052:Mitogen-Activated Protein Kinase 3