title: Rapid intranasal delivery of chloramphenicol acetyltransferase in the active form to different brain regions as a model for enzyme therapy in the CNS.
abstract: BACKGROUND
  The blood brain barrier (BBB) is critical for maintaining central nervous system (CNS) homeostasis by restricting entry of potentially toxic substances. However, the BBB is a major obstacle in the treatment of neurotoxicity and neurological disorders due to the restrictive nature of the barrier to many medications. Intranasal delivery of active enzymes to the brain has therapeutic potential for the treatment of numerous CNS enzyme deficiency disorders and CNS toxicity caused by chemical threat agents.
  
  
  METHODS
  The aim of this work is to provide a sensitive model system for analyzing the rapid delivery of active enzymes into various regions of the brain with therapeutic bioavailability.
  
  
  RESULTS
  We tested intranasal delivery of chloramphenicol acetyltransferase (CAT), a relatively large (75kD) enzyme, in its active form into different regions of the brain. CAT was delivered intranasally to anaesthetized rats and enzyme activity was measured in different regions using a highly specific High Performance Thin Layer Chromatography (HP-TLC)-radiometry coupled assay. Active enzyme reached all examined areas of the brain within 15min (the earliest time point tested). In addition, the yield of enzyme activity in the brain was almost doubled in the brains of rats pre-treated with matrix metalloproteinase-9 (MMP-9).
  
  
  METHODS
  Intranasal administration of active enzymes in conjunction with MMP-9 to the CNS is both rapid and effective.
  
  
  CONCLUSIONS
  The present results suggest that intranasal enzyme therapy is a promising method for counteracting CNS chemical threat poisoning, as well as for treating CNS enzyme deficiency disorders.
authors.affiliation: Department of Anatomy, Physiology and Genetics and Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA.
authors.forename: Abhilash P
authors.initials: AP
authors.lastname: Appu
authors.affiliation: Department of Anatomy, Physiology and Genetics and Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA.
authors.forename: Peethambaran
authors.initials: P
authors.lastname: Arun
authors.affiliation: Department of Anatomy, Physiology and Genetics and Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA.
authors.forename: Jishnu K S
authors.initials: JKS
authors.lastname: Krishnan
authors.affiliation: Department of Anatomy, Physiology and Genetics and Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA.
authors.forename: John R
authors.initials: JR
authors.lastname: Moffett
authors.affiliation: Department of Anatomy, Physiology and Genetics and Neuroscience Program, Uniformed Services University of the Health Sciences, 4301 Jones Bridge Rd., Bethesda, MD 20814, USA. Electronic address: anamboodiri@usuhs.edu.
authors.forename: Aryan M A
authors.initials: AMA
authors.lastname: Namboodiri
mesh_terms: D000281:Administration, Intranasal; D000818:Animals; D001682:Biological Availability; D001921:Brain / Q000378:metabolism*; D015500:Chloramphenicol O-Acetyltransferase / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D057487:Enzyme Therapy / Q000379:methods*; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D015500:Chloramphenicol O-Acetyltransferase; D020780:Matrix Metalloproteinase 9
keywords: Bioavailability; Catalytic bioscavenger; Enzyme deficiency diseases; Glymphatic system; Organophosphate chemical threat agents