title: Inhibition of growth in young mice treated with pentazocine: reversal by naltrexone.
abstract: One week old mice were injected subcutaneously once daily with d,1-methadone (5 mg/kg), pentazocine, naltrexone, naloxone, nalorphine or nalbuphine, each at 10 mg/kg. The remaining half of each litter was used as control. Only methadone and pentazocine groups showed reduced weight gain after 3 weeks of treatment (P < 0.01). Injection of pentazocine in dosages of 5-20 mg/kg inhibited weight gain and protein synthesis in a dose-related manner. The incorporation of labeled leucine was followed in brain, liver and muscles. Methadone and pentazocine groups showed a significant decrease in protein synthesis in all tissues studied. The nalbuphine, nalorphine, naloxone, and naltrexone-treated groups incorporated leucine normally, correlating with normal weight gain. These data suggest that pentazocine, unlike the other mixed agonist-antagonists and antagonists, adversely affects the growth of very young animals when administered chronically. A specific opioid effect is suggested by the fact that naltrexone given concomitantly with the pentazocine prevents development of the biochemical lesion.
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001921:Brain / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006128:Growth / Q000187:drug effects*; D008099:Liver / Q000378:metabolism; D051379:Mice; D009124:Muscle Proteins / Q000096:biosynthesis; D009270:Naloxone / Q000031:analogs & derivatives*; D009271:Naltrexone / Q000494:pharmacology*; D010423:Pentazocine / Q000037:antagonists & inhibitors*; D014176:Protein Biosynthesis; D011957:Receptors, Opioid / Q000187:drug effects
chemical_list: D009124:Muscle Proteins; D011957:Receptors, Opioid; D009270:Naloxone; D009271:Naltrexone; D010423:Pentazocine