Potentiation of [D-ala2]enkephalinamide analgesia in rats by thiorphan.
The effect of thiorphan, an inhibitor of enkephalin dipeptidyl carboxypeptidase, was tested in the rat tail-flick test. When given alone up to 100 mg/kg s.c., thiorphan had no effect. However, thiorphan (30 mg/kg, s.c.) potentiated intraventricularly administered [D-Ala2,Met5]enkephalinamide (DEAEM) and its [Leu5]-derivative, whereas it had no effect on [D-Ala2,Met5]enkephalin, [D-Met2,Pro5]enkephalinamide, or morphine. Potentiation of DAEAM by thiorphan was dose-responsive and naloxone reversible. The most efficient enhancement of the analgesic effects of DAEAM was seen when the two drugs were co-administrated in rapid succession. Thus, thiorphan potentiation of opioid-peptide induced analgesia in the rat is similar to that seen in the mouse.
D000603:Amino Acids, Sulfur / Q000494:pharmacology*; D000700:Analgesics; D000818:Animals; D004357:Drug Synergism; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D015260:Neprilysin; D009619:Nociceptors / Q000187:drug effects; D011480:Protease Inhibitors; D051381:Rats; D011919:Rats, Inbred Strains; D015244:Thiorphan; D013997:Time Factors; D008625:Tiopronin / Q000031:analogs & derivatives / Q000494:pharmacology*
D000603:Amino Acids, Sulfur; D000700:Analgesics; D011480:Protease Inhibitors; D009270:Naloxone; D004744:Enkephalin, Methionine; C022118:enkephalinamide-Met, Ala(2)-; D015244:Thiorphan; D008625:Tiopronin; D015260:Neprilysin