Evidence for the involvement of opioidergic systems in medprotine-induced analgesia in the mouse.
Intramuscular administration of medprotine, a protein fraction of human placenta (30-300 kDa), produced dose-dependent and long lasting analgesia as evaluated by various analgesic tests in mice. Activity was found in a dose range of 0.05-0.6 mg/kg in the phenylbenzoquinone and acetic acid writhing tests and 1.5-5 mg/kg in the hot-plate test. In this latter model, medprotine enhanced morphine-induced analgesia. Pretreatment with naloxone antagonized the effect of medprotine in all assays. The antinociceptive response of medprotine was not modified after a ten day pretreatment and no overt withdrawal symptom could be observed after either interruption of chronic treatment or administration of a precipitating dose of naloxone. It is concluded that the analgesic activity of medprotine may be mediated through either the opiate receptors or activation of endogenous opioidergic systems.
Caruso
A
A
Institute of Pharmacology, University of Catania Medical School, Italy.
Cutuli
V M
VM
Candido
P
P
De Bernardis
E
E
Amico-Roxas
M
M
D000085:Acetates; D000700:Analgesics / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D016227:Benzoquinones; D004723:Endorphins / Q000502:physiology*; D006358:Hot Temperature; D007273:Injections, Intramuscular; D008297:Male; D051379:Mice; D009270:Naloxone / Q000494:pharmacology; D010147:Pain Measurement / Q000187:drug effects; D011257:Pregnancy Proteins / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013375:Substance Withdrawal Syndrome / Q000523:psychology
D000085:Acetates; D000700:Analgesics; D016227:Benzoquinones; D004723:Endorphins; D011257:Pregnancy Proteins; C029322:phenylbenzoquinone; D009270:Naloxone