Morphine analgesia and tolerance in mice selectively bred for divergent swim stress-induced analgesia.
Morphine-induced analgesia and tolerance were examined in Swiss Webster mice selectively bred for high and low swim stress-induced analgesia. Morphine produced a dose-dependent analgesia in both lines; it was 4-fold more potent in the high analgesia line than in the low analgesia line. Despite the differences in morphine-induced analgesia, the degree of tolerance was the same in both lines. Together, these data suggest that selective breeding of mice for high and low swim stress-induced analgesia produced a striking difference in morphine-induced analgesia without affecting the degree of tolerance. Thus, while there is a common genetic determination in swim stress-induced and morphine-induced analgesia, the development of tolerance to morphine possibly relies on a different genetic background.
Lutfy
K
K
Department of Pharmacology, School of Medicine, University of California, Irvine 92717.
Sadowski
B
B
Kwon
I S
IS
Weber
E
E
D000698:Analgesia; D000704:Analysis of Variance; D000818:Animals; D001947:Breeding; D004361:Drug Tolerance / Q000235:genetics*; D008297:Male; D051379:Mice; D009020:Morphine / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000235:genetics* / Q000502:physiology; D013045:Species Specificity; D013312:Stress, Physiological / Q000503:physiopathology; D013550:Swimming
D011957:Receptors, Opioid; D009020:Morphine