Interleukin-1beta-induced increases of plasma catecholamine levels in rats: enhancement by superior cervical ganglionectomy.

In urethane-anesthetized rats, we examined the effect of bilateral superior cervical ganglionectomy on interleukin-1beta (IL-1beta)-induced elevation of plasma catecholamines. In sham-operated rats, intracerebroventricularly (i.c.v.) administered IL-1beta (100 ng/animal) effectively elevated plasma noradrenaline rather than plasma adrenaline. In superior cervical ganglionectomized rats, however, IL-1beta 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.