| Literature DB >> 2169936 |
Abstract
1. The availability of the non-peptide delta-opioid receptor antagonist naltrindole has provided the possibility for in vivo studies on the function of delta-opioid receptors. We have studied the effects of naltrindole on swim-stress-induced antinociception in adult and neonatal rats. 2. Adult, 25 and 20 day old rats were stressed by warm water (20 degrees C) swimming for 3 min periods and antinociception was assessed by the tail immersion test (50 degrees C). 3. Naltrindole (0.5 and 1 mg kg-1) antagonized swim-stress-induced antinociception in adult and 25 day old rats but in 20 day old rats naltrindole (1 mg kg-1) was without effect. 4. Antinociception induced by the highly mu-opioid receptor selective agonist alfentanil was completely antagonized by naloxone (1 mg kg-1) but virtually unaffected by naltrindole (1 mg kg-1). 5. Neither naloxone nor naltrindole (1 mg kg-1) antagonized swim-stress-induced rises in plasma corticosterone in adult rats at the time of peak antinociception. 6. In conclusion, naltrindole shows in vivo antagonism of opioid-mediated responses. Swim-stress-induced antinociception is mediated through the delta-opioid receptor in 25 day old and adult rats and through the mu-opioid site in 20 day old animals.Entities:
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Year: 1990 PMID： 2169936 PMCID： PMC1917588 DOI： 10.1111/j.1476-5381.1990.tb14076.x
Source DB: PubMed Journal: Br J Pharmacol ISSN： 0007-1188 Impact factor: 8.739