Effects of naloxone and nalmefene in rat spinal cord injury induced by the ventral compression technique.
The neural injury prevention capabilities of narcotic antagonists have previously been reported. Of the available narcotic antagonists, naloxone has been the most widely studied. Other agents with higher potency, longer half-lives, and greater specificity, however, may be more desirable for the prevention of the "secondary injury" following a primary neural insult. The relative neural injury prevention efficacies of the various narcotic antagonists is not known. The establishment of the relative effectiveness of these drugs is warranted and is of potential clinical importance. Therefore, a study was undertaken to compare the effects of the two narcotic antagonists, naloxone and nalmefene, with respect to their neuro-protective efficacy following experimental spinal cord injury (SCI) in rats. Ninety adult Sprague-Dawley rats were divided into three groups--control; naloxone (2 mg/kg i.p., 45 min following injury); and nalmefene (0.1 mg/kg i.p., 45 min following injury)--following lesioning with the ventral SCI technique. Results were evaluated by the inclined-plane technique and neurologic examination at 1 day and 1 week following injury. Histomorphological evaluation of the injured segment of spinal cord was performed following euthanasia at 1 week following injury. A significant improvement (compared with the control group) was noted in both treatment groups. This was observed with respect to neurological examination and inclined-plane scores in both treatment groups at 24 h and 1 week following lesioning (with a significance level of at least p less than 0.001; analysis of variance). The nalmefene group demonstrated a greater level of function than the naloxone group at both 24 h and 1 week following injury (not significant; p greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Benzel
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Division of Neurosurgery, University of New Mexico School of Medicine, Albuquerque 87131.
Khare
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Fowler
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D000818:Animals; D004353:Drug Evaluation, Preclinical; D007405:Intervertebral Disc Displacement / Q000150:complications; D009270:Naloxone / Q000627:therapeutic use*; D009271:Naltrexone / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D009409:Nerve Crush; D010243:Paralysis / Q000209:etiology / Q000517:prevention & control*; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects; D017473:Receptors, Opioid, kappa; D013119:Spinal Cord Injuries / Q000150:complications / Q000188:drug therapy*; D016103:Spinal Fractures / Q000150:complications
D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D009270:Naloxone; D009271:Naltrexone; C038981:nalmefene