BLOOD GLUCOSE AND BRAIN CATECHOLAMINE LEVELS IN THE CAT FOLLOWING THE INJECTION OF MORPHINE INTO THE CEREBROSPINAL FLUID

¹ Department of Pharmacology and Toxicology, Dartmouth Medical School, Hanover, New Hampshire

In unanesthetized cats intravenous and intraventricular but not intracisternal injections of morphine evoked marked hyperglycemia and partial depletion of hypothalamic stores of norepinephrine. Although the depletion of hypothalamic norepinephrine occurred in 1 hour, a significant reduction of the norepinephrine content did not occur in other brain areas. The dopamine content of the caudate nucleus also remained unchanged. Ablation of area postrema did not interfere with either hyperglycemia or the norepinephrine depletion evoked by morphine.

Since hyperglycemia and norepinephrine depletion occurred after intraventricular injections of morphine that were approximately [unknown] the required intravenous dose, and since these effects were related in their occurrence and time course, it is proposed that they are initiated by an action of morphine on a receptor area located on or near the surface of the cerebroventricular system.