Morphine induced fighting and prior social experience

Strain differences in morphine-withdrawal-induced aggression in rats

“…On the other hand, this study reveals that the Wistar and Long-Evans strains both display significant fighting during morphine withdrawal, with the Long-Evans bcing by far the most aggressive. Such aetivity was reported for the Long-Evans strain after the eompletion of our study (Thor, Hoats, & Thor, 1970) but without a direct comparison to another strain. The present study also differs in that the peak of aggression occurred at 60 to 70 h into the withdrawal period, compared to a maximum at 75 to 95 h or 85 to 100 h. as found in previous investigations (Thor.…”

“…Several investigations have shown that the withdrawal of morphine from physically dependent rats leads to the occurrence of fighting behavior in male Sprague-Dawley rats (Boshka, Weisman, & Thor, 1966;Thor & Teel, 1968) and Long-Evans rats (Thor, Hoats, & Thor, 1970). These authors found that the fighting behavior began about 60 to 75 h after withdrawal from morphine, continued for 50 to 60 h, then subsided to negligible levels.…”

Morphine-amphetamine-induced fighting and interim socialization

“…Fighting is prolonged for rats maintained in isolation during the interdrug interval. Thor & Teel (1968) and Thor, Hoats, & Thor (1970) have indicated that laboratory rats will exhibit aggressive behavior for extended intervals during withdrawal from previous morphine administration and that the extent and intensity of fighting is positively related to prior morphine dosage. D-amphetamine in moderate dosage, given during withdrawal from the narcotic drug etonitazene, potentiates fighting among grouped rats (Florea & Thor, 1968), and a single dose of amphetamine, given 90 h after withdrawal from morphine, stimulates traumatic fighting (Thor, 1969;in press).…”