Central or peripheral norepinephrine depletion enhances MK-801-induced plasma corticosterone level in mice

To investigate the involvement of central or peripheral catecholaminergic systems in the MK-801-induced increase in plasma corticosterone and interleukin-6 levels, we pretreated mice either intracerebroventricularly (i.c.v.) or intraperitoneally (i.p.) with 6-hydroxydopamine (6-OHDA) which depletes catecholamines. Pretreatment of animals with 6-OHDA (50 microg i.c.v. or 100 mg/kg i.p.) significantly enhanced the MK-801 (1 microg i.c.v.)-induced increase in plasma corticosterone level. On the other hand, pretreatment of mice with 6-OHDA (50 microg i.c.v. or 100 mg/kg i.p.) did not affect the MK-801 (1 microg i.c.v.)-induced increase in plasma IL-6 level. These results suggest that central and peripheral catecholaminergic systems are involved in the suppressive regulation of MK-801-induced plasma corticosterone level.