[Depressive-like state and sleep in laboratory mice].
In order to induce the state of anhedonia, a key symptom of depression, mice were subjected to a one-month stress procedure comprised of various stressors. Anhedonic state was defined by a reduction of preference for sucrose solution over tap water. Conventional cortical and neck-muscle electrodes were implanted to control and stressed animals under chloral-hydrate anesthesia. After a two-week recovery and habituation period, mice from chronically stressed group were re-subjected to five-day stress, and the anhedonic state was verified. As not all the stressed mice displayed a decrease in sucrose preference, animals were divided in two groups: stressed-non-anhedonic and stressed-anhedonic animals. Seven-day continuous polygraphic recording was carried out in animals from both stressed groups and the control group in recording chambers under conditions of 12/12-hour light/dark schedule. The anhedonic mice demonstrated a significant advanced shift in circadian distribution of paradoxical sleep and increased amount of paradoxical sleep during the light period. In the course of the dark period, the anhedonic group showed a slight but significant decrease in total amount of slow-wave sleep as compared to the non-anhedonic and control groups. The results suggest that the changes in sleep structure documented in the model of anhedonia are similar to those described for human depression.
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D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D003863:Depression / Q000503:physiopathology*; D004569:Electroencephalography / Q000379:methods; D005518:Food Preferences / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D012895:Sleep, REM / Q000502:physiology*; D013312:Stress, Physiological / Q000502:physiology*