[Long-term enhancement of morphine hypalgesia as a result of periodic blockade of opiate receptors using naloxone].
A significant enhancement of the analgetic effect of morphine (6 mg/kg, subcutaneously; tail withdrawal reflex at 60 degrees C) was observed in rats 3-4 hours after single naloxone (1 mg/kg) administration. Periodical naloxone injection (0.5 mg/kg, subcutaneously, 3 times per day at 3.5-hour intervals for 3 days) led to a prominent and long-term (testing on the 20th and 105th hour after the last naloxone administration) enhancement of morphine analgesia (2.6 mg/kg subcutaneously) and insignificant inhibition of stress analgesia during two-hour immobilization of animals. These modifications of morphine and stress analgetic effects are considered a result of adaptive changes of opiate receptors after their blockade.
Kiiatkin
E A
EA
Zhukov
V N
VN
D000698:Analgesia; D000818:Animals; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009270:Naloxone / Q000494:pharmacology*; D051381:Rats; D011957:Receptors, Opioid / Q000187:drug effects*; D013997:Time Factors
D011957:Receptors, Opioid; D009270:Naloxone; D009020:Morphine
Dlitel'noe usilenie morfinovoĭ gipal'gezii kak resul'tat periodicheskoĭ blokady opiatnykh retseptorov naloksonom.