Interleukin-1β-Induced Increases of Plasma Catecholamine Levels in Rats: Enhancement by Superior Cervical Ganglionectomy

Abstract

In urethane-anesthetized rats, we examined the effect of bilateral superior cervical ganglionectomy on interleukin-1β (IL-1β)-induced elevation of plasma catecholamines. In sham-operated rats, intracerebroventricularly (i.c.v.) administered IL-1β (100 ng/animal) effectively elevated plasma noradrenaline rather than plasma adrenaline. In superior cervical ganglionectomized rats, however, IL-1β significantly elevated adrenaline to a greater extent than noradrenaline, and they were attenuated by i.c.v. administration of melatonin (100 ng/animal). Superior cervical ganglionectomy effectively reduced the plasma level of melatonin and urinary excretion of 6-sulfatoxymelatonin (a main urinary melatonin metabolite). These results suggest that superior cervical ganglia inhibit central sympatho-adrenomedullary outflow (especially adrenomedullary outflow) by increasing melatonin synthesis in the pineal gland of rats.