title: A reassessment of P2X7 receptor inhibition as a neuroprotective strategy in rat models of contusion injury.
abstract: These experiments were completed as part of an NIH "Facilities of Research Excellence in Spinal Cord Injury" contract to support independent replication of published studies that could be considered for eventual clinical testing. Recent studies have reported that selective inhibition of the P2X7 receptor improves both the functional and histopathological consequences of a contusive spinal cord injury (SCI) in rats. We repeated two published studies reporting the beneficial effects of pyridoxal-5'-phosphate-6-azophenyl-2'-4'-disulphonic acid (PPADS) or Brilliant blue G (BBG) treatment after SCI (Wang et al., 2004 and Peng et al., 2009). Mild thoracic SCI was first produced in Experiment 1 by means of the MASCIS impactor at T10 (height 6.25 mm, weight 10 g) followed by intraspinal administration of a P2X7 antagonist (2 μl/10 mM) after injury. Treatment with PPADS or another highly selective P2X7R antagonist Brilliant Blue G (BBG) (2 μl/02 mM) did not improve locomotive (BBB rating scale) over a 7 week period compared to vehicle treated rats. Also, secondary histopathological changes in terms of overall lesion and cavity volume were not significantly different between the PPADS, BBG, and vehicle treated animals. In the second experiment, the systemic administration of BBG (10 or 50 mg/kg, iv) 15 min, 24 and 72 h after moderate (12.5 mm) SCI failed to significantly improve motor recovery or histopathological outcome over the 6 week observational period. Although we cannot conclude that there will be no long-term beneficial effects in other spinal cord injury models using selective P2X7 receptor antagonists at different doses or treatment durations, we caution researchers that this potentially exciting therapy requires further preclinical investigations before the implementation of clinical trials targeting severe SCI patients.
authors.affiliation: The Miami Project to Cure Paralysis, Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Marcillo
authors.forename: Beata
authors.initials: B
authors.lastname: Frydel
authors.forename: Helen M
authors.initials: HM
authors.lastname: Bramlett
authors.forename: W Dalton
authors.initials: WD
authors.lastname: Dietrich
mesh_terms: D000818:Animals; D003288:Contusions / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control*; D004195:Disease Models, Animal; D004353:Drug Evaluation, Preclinical / Q000379:methods; D005260:Female; D018696:Neuroprotective Agents / Q000008:administration & dosage* / Q000494:pharmacology; D058920:Purinergic P2X Receptor Antagonists / Q000008:administration & dosage*; D011732:Pyridoxal Phosphate / Q000008:administration & dosage / Q000031:analogs & derivatives; D051381:Rats; D011916:Rats, Inbred F344; D017207:Rats, Sprague-Dawley; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism* / Q000502:physiology; D012394:Rosaniline Dyes / Q000008:administration & dosage; D013119:Spinal Cord Injuries / Q000378:metabolism* / Q000473:pathology / Q000517:prevention & control*
chemical_list: D018696:Neuroprotective Agents; D058920:Purinergic P2X Receptor Antagonists; D058486:Receptors, Purinergic P2X7; D012394:Rosaniline Dyes; C077792:pyridoxal phosphate-6-azophenyl-2',4'-disulfonic acid; D011732:Pyridoxal Phosphate; C004692:coomassie Brilliant Blue
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