title: Oral administration of cytosolic PLA2 inhibitor arachidonyl trifluoromethyl ketone ameliorates cauda equina compression injury in rats.
abstract: BACKGROUND
  Phospholipase A2 (PLA2)-derived proinflammatory lipid mediators such as prostaglandin E2 (PGE2), leukotrienes B4 (LTB4), lysophosphatidylcholine (LPC), and free fatty acids (FFA) are implicated in spinal cord injury (SCI) pathologies. Reducing the levels of these injurious bioactive lipid mediators is reported to ameliorate SCI. However, the specific role of the group IVA isoform of PLA2 cytosolic PLA2 (cPLA2) in lumbar spinal canal stenosis (LSS) due to cauda equina compression (CEC) injury is not clear. In this study, we investigated the role of cPLA2 in a rat model of CEC using a non-toxic cPLA2-preferential inhibitor, arachidonyl trifluoromethyl ketone (ATK).
  
  
  METHODS
  LSS was induced in adult female rats by CEC procedure using silicone blocks within the epidural spaces of L4 to L6 vertebrae. cPLA2 inhibitor ATK (7.5 mg/kg) was administered by oral gavage at 2 h following the CEC. cPLA2-derived injurious lipid mediators and the expression/activity of cPLA2, 5-lipoxygenase (5-LOX), and cyclooxygenase-2 (COX-2) were assessed. ATK-treated (CEC + ATK) were compared with vehicle-treated (CEC + VEH) animals in terms of myelin levels, pain threshold, and motor function.
  
  
  RESULTS
  ATK treatment of CEC animals reduced the phosphorylation of cPLA2 (pcPLA2) determined by Western blot, improved locomotor function evaluated by rotarod task, and reduced pain threshold evaluated by mechanical hyperalgesia method. Levels of FFA and LPC, along with PGE2 and LTB4, were reduced in CEC + ATK compared with CEC + VEH group. However, ATK treatment reduced neither the activity/expression of 5-LOX nor the expression of COX-2 in CEC + VEH animals. Increased cPLA2 activity in the spinal cord from CEC + VEH animals correlated well with decreased spinal cord as well as cauda equina fiber myelin levels, which were restored after ATK treatment.
  
  
  CONCLUSIONS
  The data indicate that cPLA2 activity plays a significant role in tissue injury and pain after LSS. Reducing the levels of proinflammatory and tissue damaging eicosanoids and the deleterious lipid mediator LPC shows therapeutic potential. ATK inhibits cPLA2 activity, thereby decreasing the levels of injurious lipid mediators, reducing pain, improving functional deficits, and conferring protection against LSS injury. Thus, it shows potential for preclinical evaluation in LSS.
authors.affiliation: Department of Pediatrics, Medical University of South Carolina, Charleston, SC, 29425, USA. khanm@musc.edu.
authors.forename: Mushfiquddin
authors.initials: M
authors.lastname: Khan
authors.affiliation: Department of Pediatrics, Medical University of South Carolina, Charleston, SC, 29425, USA. anandak@musc.edu.
authors.forename: Anandakumar
authors.initials: A
authors.lastname: Shunmugavel
authors.affiliation: Department of Pediatrics, Medical University of South Carolina, Charleston, SC, 29425, USA. dhammu@musc.edu.
authors.forename: Tajinder S
authors.initials: TS
authors.lastname: Dhammu
authors.affiliation: Department of Pediatrics, Medical University of South Carolina, Charleston, SC, 29425, USA. fumiyo@health.nop.kagoshima-u.ac.jp.|School of Health Science, Kagoshima University, Kagoshima, Japan. fumiyo@health.nop.kagoshima-u.ac.jp.
authors.forename: Fumiyo
authors.initials: F
authors.lastname: Matsuda
authors.affiliation: Department of Pathology and Laboratory Medicine, Medical University of South Carolina, Charleston, SC, USA. singha@musc.edu.|Ralph H. Johnson VA Medical Center, Charleston, SC, USA. singha@musc.edu.
authors.forename: Avtar K
authors.initials: AK
authors.lastname: Singh
authors.affiliation: Department of Pediatrics, Medical University of South Carolina, Charleston, SC, 29425, USA. singhi@musc.edu.
authors.forename: Inderjit
authors.initials: I
authors.lastname: Singh
mesh_terms: D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism; D001095:Arachidonic Acids / Q000008:administration & dosage*; D051546:Cyclooxygenase 2 / Q000378:metabolism; D015232:Dinoprostone / Q000378:metabolism; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000008:administration & dosage*; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D006930:Hyperalgesia / Q000188:drug therapy / Q000209:etiology; D007975:Leukotriene B4 / Q000378:metabolism; D008124:Locomotion / Q000187:drug effects; D008244:Lysophosphatidylcholines / Q000378:metabolism; D059225:Nociception / Q000187:drug effects; D011128:Polyradiculopathy / Q000150:complications / Q000188:drug therapy*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D001095:Arachidonic Acids; D004791:Enzyme Inhibitors; D005227:Fatty Acids; D008244:Lysophosphatidylcholines; C081565:arachidonyltrifluoromethane; D007975:Leukotriene B4; D001094:Arachidonate 5-Lipoxygenase; D051546:Cyclooxygenase 2; D015232:Dinoprostone