Effect of lethal doses of morphine on brain amines in isolated and aggregated mice.

Brain levels of norepinephrine, dopamine and serotonin were measured in isolated and aggregated mice after lethal doses of morphine. Although morphine significantly lowered all three brain monoamines there were no significant differences between isolated and aggregated mice. Measurements of brain morphine concentrations also failed to demonstrate any differences which could account for the difference in lethality observed in isolated and aggregated mice.