DIFFERENTIAL RESPONSES OF BRAIN, LIVER, AND MUSCLE GLYCOGEN TO OPIATES AND SURGICAL STRESS

We examined the effects of intracerebroventricular (ICV) cannula impla ntation followed by the administration of morphine sulfate (MOR) and i ts metabolite, morphine-6-glucuronide (M6G), on the glycogen content o f the brain, liver, and muscle. ICV cannulation resulted in nearly a 3 0% reduction in brain glycogen, and ICV MOR resulted in a 36% reductio n in liver glycogen content compared to time-matched controls, but it had no additional effect on either the brain or muscle glycogen conten t, ICV M6G shelved a more significant reduction, to 50% of liver glyco gen, but it had no effect on either brain or muscle glycogen. Neither IV MOR nor M6G produced any significant alteration in tissue glycogen content. These results indicate that the stress response associated wi th neurosurgery, especially the placement of the ICV cannula, is assoc iated with a decrement in brain glycogen. The activation of opioid rec eptors in the brain results in enhanced hepatic glycogenolysis but has no additional effect on the brain glycogen content.