Circadian Disruption of Body Core Temperature and Rest-Activity Rhythms after General (Propofol) Anesthesia in Rats

Background: General anesthesia is commonly associated with sleep disorders, fatigue, drowsiness, and mood alterations in patients. The authors examined whether general (propofol) anesthesia can impact the circadian temporal structure by disturbing circadian rest-activity and body temperature rhythms under normal light-dark conditions (light-dark 12:12 h) in rats. Methods: A group of rats was anesthetized with propofol, and another was injected with 10% Intralipid, which was used as a control lipidic solution. The authors examined six groups of rats according to die Zeitgeber time of intraperitoneal administration (ZT6, ZT10, ZT16) and the substance injected (propofol or Intralipid). Results: On the day after anesthesia, propofol induced a significant 60- to 80-min phase advance of both rest-activity and body temperature rhythms. A significant 45- to 60-min phase advance of body temperature and a significant 20-min phase advance of rest-activity were still observed on the second day after anesthesia. The amplitudes of both rest-activity and body temperature rhythms were decreased on the first and second days after anesthesia. The 24-h mean rest-activity rhythm was decreased on the day after anesthesia, whereas the 24-h mean body temperature rhythm was not modified. Conclusion: The results demonstrate the disturbing effects of propofol anesthesia on the circadian time structure in rats under normal light conditions.