Actions of microelectrophoretically applied glucocorticoid hormones on reticular formation neurones in the rat

The effects of microelectrophoretic application of hydrocortisone (HC) and corticosterone (CS) on single neurones of the brainstem reticular formation (RF) were investigated in rats under urethane anaesthesia. Ejecting currents generally ranged from 5 to 20nA. HC and CS behaved similarly in that they produced an excitatory effect in 26% and 24% of the neurones, respectively, an inhibition in 15% and 17% and no effect in 59% of neurones. The excitatory effects predominated in the caudal portion of the FR and the inhibitory effects in the rostral RF. The different distribution of the effects may be related to functional differences between the two RF areas.