AJP - Regulatory, Integrative and Comparative Physiology, Vol 253, Issue 1 25-R30, Copyright © 1987 by American Physiological Society
Effects of corticosterone on neurons of reticular formation in rats
G. L. Avanzino, R. Ermirio, P. Ruggeri and C. E. Cogo
The effects of microelectrophoretic application of corticosterone (CS) on
single neurons of the brain stem reticular formation (RF) were investigated
and then compared with the effects produced on the same neurons by
intravenous administration of CS. The experiments were done in two groups
of rats, one anesthetized with urethan and the other with pentobarbital
sodium because these anesthetics cause different increases of basal
concentration of plasma CS. Microelectrophoretic application of CS to
neurons in the caudal portion of RF caused primarily excitatory effects,
whereas inhibitory effects were observed in neurons of the rostral portion
of the RF. The intravenous injection of CS (5 micrograms/100 g body wt)
always produced the same effects as microelectrophoretic application. Under
our experimental conditions the increase in plasma CS concentration
produced by the intravenous injection of CS was found to be within the
physiological range for the rat. The different anatomical distribution of
units within the RF responding with either excitation or inhibition may be
related to functional differences of the two RF areas.
