title: Effects of methylprednisolone on axonal depression induced by hypoxia, gamma-aminobutyric acid, and (+/-)-8-hydroxy-dipropylaminotetralin hydrobromide.
abstract: OBJECTIVE
  We sought to confirm the effects of methylprednisolone (MP) on axonal depression induced by hypoxia, gamma-aminobutyric acid (GABA), and (+/-)-8-hydroxy-dipropylaminotetralin hydrobromide (8-OH-DPAT).
  
  
  METHODS
  Compound action potentials were recorded to assess the effects of MP in neonatal rat spinal cord axons. Longitudinally hemisected spinal cords were superfused for 120 minutes in Ringer's solution saturated with 95% N2 and 5% CO2. The effect of MP on GABA- and 8-OH-DPAT-induced axonal depression was analyzed with oxygenated isolated dorsal columns.
  
  
  RESULTS
  Hypoxia (120 min) significantly reduced the response amplitudes in hemicord preparations. MP (30 micromol/L) prevented hypoxia-induced depression of action potential amplitudes. In oxygenated dorsal column preparations, GABA (50 micromol/L) significantly reduced action potential amplitudes. At 10, 30, and 100 micromol/L, MP had no effect on axonal excitability and GABA-induced axonal depression. 8-OH-DPAT (100 micromol/L) significantly reduced the action potential amplitude. MP (10, 30, 50, and 100 micromol/L) reduced 8-OH-DPAT-induced amplitude depression in a dose-dependent manner.
  
  
  CONCLUSIONS
  At the higher concentrations, MP protected spinal cord axons against hypoxia-induced excitability loss. It had an effect on serotonin 1A-induced axonal depression but not on GABA-induced depression.
authors.affiliation: W.M. Keck Center for Collaborative Neuroscience, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA. tsasaki@fmu.ac.jp
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sasaki
authors.forename: Jun
authors.initials: J
authors.lastname: Sakuma
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Ichikawa
authors.forename: Masato
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Pankaj
authors.initials: P
authors.lastname: Tiwari
authors.forename: Wise
authors.initials: W
authors.lastname: Young
authors.forename: Namio
authors.initials: N
authors.lastname: Kodama
mesh_terms: D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology*; D000818:Animals; D001369:Axons / Q000187:drug effects* / Q000502:physiology; D000860:Hypoxia / Q000503:physiopathology*; D066298:In Vitro Techniques; D008775:Methylprednisolone / Q000494:pharmacology*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D051381:Rats; D020318:Rats, Long-Evans; D013116:Spinal Cord / Q000187:drug effects* / Q000503:physiopathology; D005680:gamma-Aminobutyric Acid / Q000494:pharmacology*
chemical_list: D018696:Neuroprotective Agents; D005680:gamma-Aminobutyric Acid; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D008775:Methylprednisolone