Effects of morphine on cortex, hippocampus and medial thalamus: a comparison between urethane-anaesthetized and paralyzed-awake rats.

Urethane is often used as a central anaesthetic in neurophysiological studies of drug effects. In this experiment, the effect of morphine on cortical EEG and single units of hippocampus and medial thalamus were compared in urethane-anaesthetized and paralyzed-awake rats. In each case, there was evidence of a morphine-urethane interaction, suggesting caution in the interpretation of drug studies using urethane-anaesthetized animals.