Effects Of REM Sleep Deprivation On Depressive-behaviors And Brain Monoamines In Rats Treated With Chronic Stress

Background and Objective: Antidepressant drugs need to be administered for several weeks before a therapeutic response is achieved. However, Sleep deprivation exerts antidepressant effects after only one night of deprivation, which suggests that a rapid antidepressant response is possible, but the exact mechanism behind this effect still remains unclear. Enhancements of serotonergic norepinephrinergic and dopaminergic neurotransmission should be responsible for it. This study is designed to investigate the effects of REM(rapid eye movement) sleep deprivation (REMSD) on depressive-behaviors and brain monoamines in rats treated with chronic mild unpredicted stresses.Materials and Methods: Sprague-Dawley rats were divided into four groups randomly:1) normal control rats . 2)chronic stress 3)72hours REM sleep deprivation and 4) tank control rats. REM sleep deprivation was performed by flowerpot technique. Rats in chronic stress group were exposed to unpredicted mild stressors for 21 consecutive days. An open field test was repeated three times to evaluate the depressive-behavior during the experiment. Concentrations of monoamines in hippocampus, frontal cortex, hypothalamus and striatum were measured by high performance liquid chromatography coupled with fluorescence detection.Results: Open field tests showed that the total activity was reduced after 21 days stresses, while 72 hours REM sleep deprivation reversed thiseffect. There were significant differences in 5-HT and NE levels in the hippocampus or hypothalamus respectively among the four groups of rats. Though there was no significant differences in tryptophan levels in the hippocampus among the four groups of rats, it seems to be increased after 21 days stresses, and a declined trend appeared after 72 hours REM sleep deprivation. There was no difference in dopamine concentrations among the four groups . Conclusions:1. Rats showed a depressive-behaviors after 21 days stresses, while 72hours REM sleep deprivation could reverse this effect;2. Chronic mild stress produced a decline in 5-HT levels in the hippocampus while 72hours REM sleep deprivation could reverse this effect. These results are consistent with a role of serotonin in the antidepressant effects of sleep deprivation;3. Chronic mild stress produced a decline in NE levels in the hypothalamus, while 72hours REM sleep deprivation can increase NE levels in some degree, though there was no significant differences. It suggests that perhaps NE play a role in the antidepressant effect of REM sleep deprivation;4. Chronic mild stress and REM sleep deprivation produced no effects in DA levels in the striatum among the four groups rats. These results do not support the hypothesis that the antidepressant effects of REM sleep deprivation are due to an increase in DA release.