Changed morphine sensitivity of morphine-dependent rats after laser exposure of the cerebral prefrontal cortex.

We studied the effect of bilateral laser exposure of the cerebral prefrontal cortex in morphine-dependent rats on their sensitivity to positive reinforcing and toxic effect of morphine. Laser exposure led to partial deafferentation of the cingulum. Exposure of the anterior and central areas of the prefrontal cortex stimulated self-administration of low morphine doses and had no effect on self-administration of high concentrations.

Effect of destruction of gyrus cinguli in rat brain on the development of tolerance to the analgesic effect of morphine and physical dependence on morphine.

We studied the effect of bilateral laser destruction of rat anterior cingulate gyrus on the analgesic effect of morphine and development of tolerance and physical dependence on morphine. Bilateral laser destruction of the anterior cingulate gyrus did not modulate pain sensitivity, analgesic effect of morphine, and development of morphine tolerance. Destruction of the cingulate gyrus alleviated symptoms of the abstinence syndrome in morphine-dependent animals.