title: Continuous naloxone administration via osmotic minipump decreases autotomy but has no effect on nociceptive threshold in the rat.
abstract: Rats with unilaterally sectioned sciatic nerves were continuously administered naloxone HCl (80 or 800 micrograms/h) or equivalent volumes of saline (1 or 10 microliters/h) subcutaneously via osmotic minipumps over a 2 or 5 week period. Rats receiving 80 micrograms/h naloxone for 5 weeks exhibited significantly less self-mutilation (autotomy) of the denervated foot than saline controls or rats receiving 80 micrograms/h naloxone for 2 weeks. The nociceptive threshold of intact rats infused with the same dose of naloxone was tested on a hot plate. In these animals there was no influence on the nociceptive threshold during naloxone administration for 1 week. Autotomy was also reduced in rats infused with 800 micrograms/h naloxone. The nociceptive threshold of intact rats infused with this dose of naloxone or an equivalent volume of saline (10 microliters/h) was increased, suggesting that the presence of the larger osmotic pump caused analgesia.
mesh_terms: D000818:Animals; D006801:Humans; D008297:Male; D009270:Naloxone / Q000008:administration & dosage / Q000494:pharmacology*; D009995:Osmosis; D010146:Pain / Q000188:drug therapy*; D010523:Peripheral Nervous System Diseases / Q000150:complications; D051381:Rats; D011919:Rats, Inbred Strains; D012584:Sciatic Nerve / Q000503:physiopathology; D012652:Self Mutilation / Q000188:drug therapy* / Q000209:etiology; D012684:Sensory Thresholds / Q000187:drug effects; D013997:Time Factors
chemical_list: D009270:Naloxone