Reduced inhibitory potency of serotonin reuptake blockers on central serotoninergic neurons in rats selectively deprived of rapid eye movement sleep

Previous studies showed that chronic deprivation of rapid eye movement (REM) sleep had the same behavioral effects as antidepressant drugs in helpless rats. Since long-term treatment with antidepressants is known to affect central serotoninergic neurotransmission, we investigated whether REM sleep deprivation also exerts an influence on the activity of serotoninergic neurons within the dorsal raphe nucleus (DRN) in rats. REM sleep deprivation was performed using the platform technique. Recording of serotoninergic neurons in the DRN revealed no difference in the basal firing rate, but a reduced inhibitory response to the selective serotonin (5-HT) reuptake blockers cericlamine and citalopram after repeated but not acute REM sleep deprivation. These observations suggest that REM sleep deprivation renders serotoninergic DRN neurons less sensitive to the inhibitory effect of 5-HT reuptake blockers, probably because of functional desensitization of somatodendritic 5-HT1A autoreceptors, like that previously reported after chronic treatment with several antidepressants. Accordingly, REM sleep deprivation might alleviate depression through neurophysiological mechanisms similar to those induced by antidepressants.