[The enkephalinase mechanisms of the resistance and tolerance to the analgesic effect of morphine in rats. Differences in the effects of the action of D-phenylalanine in morphine-sensitive, morphine-tolerant and morphine-resistant rats].
In morphine-sensitive (s.c. 1.5 mg/kg) Wistar rats (60%) i.p. inoculation of 300-600 mg/kg d-Phenylalanine (d-Pha) did not change the nociception (tail-flick test), but in morphine-resistant rats (40%) evoked a dose-dependent analgetic effect. In morphine-sensitive rats (40%) chronic morphine administration induced the tolerance and d-Pha injection evoked analgetic effect. Morphine injection just after d-Pha analgesia was over evoked analgetic effect in morphine-resistant and -tolerant rats. It is suggested that morphine-resistant rats have a congenital and morphine-tolerant rats an acquired high level of enkephalinase activity which blocked the morphine analgetic action.
S V
SV
Litvinova
A Iu
AIu
Kozlov
L V
LV
Kaliuzhnyĭ
D000698:Analgesia; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D004361:Drug Tolerance; D008297:Male; D009020:Morphine / Q000037:antagonists & inhibitors* / Q000494:pharmacology*; D015260:Neprilysin / Q000037:antagonists & inhibitors / Q000187:drug effects* / Q000502:physiology; D010146:Pain / Q000503:physiopathology; D010649:Phenylalanine / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D010649:Phenylalanine; D009020:Morphine; D015260:Neprilysin