THE EFFECTS OF IMMUNOLESIONS OF NERVE GROWTH FACTOR-RECEPTIVE NEURONSBY 192-IGG-SAPORIN ON SLEEP

Low-affinity nerve growth factor (NGF) receptors are present on the ch olinergic neurons of the basal forebrain. We studied the effects of 19 2 IgG-saporin, a specific immunotoxin for the NGF receptor-positive, c holinergic basal forebrain neurons, on sleep, the power spectrum of th e electroencephalogram (EEG), and body temperature. After 3 d baseline recordings, 12 male rats were injected intracerebroventricularly with 4 mu g 192 IgG-saporin. EEG, motor activity, and brain temperature we re recorded for 23 h on the first, third, fifth, and seventh day after the treatment. 192 IgG-saporin did not affect the total daily amounts but altered the circadian distribution of sleep. On days 1 and 3 afte r the injection of the immunotoxin, the amount of non-rapid-eye-moveme nt sleep (NREMS) and rapid-eye-movement sleep (REMS) increased during the dark period, whereas during the light both NREMS and REMS decrease d. On day 5, these changes were less pronounced and sleep completely r eturned to the baseline by day 7. The EEG was suppressed in each frequ ency band and each vigilance state, and, in contrast to sleep, these c hanges in EEG persisted for 7 days. Brain temperature was decreased fr om day 3. These results suggest that NGF receptor-positive, cholinergi c basal forebrain neurons are not necessary for the maintenance of tot al sleep time but contribute to the generation of normal EEG and the m aintenance of brain temperature.