NGFI-A EXPRESSION IN THE RAT-BRAIN AFTER SLEEP-DEPRIVATION

The effects of total sleep deprivation (SD) on the expression of the i mmediate-early gene NGFI-A were studied in the rat brain by in situ hy bridization. Rats were manually sleep-deprived for 3, 6, 12 and 24 h s tarting at light onset (08:00 h) and for 12 h starting at dark onset ( 20:00 h). SD performed during the day induced a marked increase in NGF I-A mRNA levels with respect to sleep controls in many cerebrocortical areas and caudate-putamen, which was most evident after 6 h SD. A dec rease was seen in hippocampus and thalamus, particularly after 12 h SD . Rats sleep-deprived for 12 h during the night showed an increase in NGFI-A expression in some cortical areas while rats sleep-deprived for 24 h showed few changes with respect to controls. The pattern of NGFI -A expression after forced wakefulness showed some differences from th at observed after spontaneous wakefulness [M. Pompeiano, C. Cirelli an d G. Tononi, Immediate early genes in spontaneous wakefulness and slee p: expression of c-fos and NGFI-A. mRNA and protein, J. Sleep Res., 3 (1994) 80-96]. These observations are discussed with respect to the fu nctional consequences of wakefulness in specific brain areas.