EFFECTS OF PROLONGED SLEEP-DEPRIVATION ON LOCAL-RATES OF CEREBRAL ENERGY-METABOLISM IN FREELY MOVING RATS

Although sleep deprivation interferes with biological processes essent ial for performance, health, and longevity, previous studies have fail ed to reveal any structural or functional changes in brain. We have th erefore measured local rates of cerebral glucose utilization (ICMR(glc )) with the quantitative autoradiographic 2-C-14-deoxyglucose method i n an effort to determine if and, if so, where sleep deprivation might affect function in sleep-deprived rats. Sleep deprivation was maintain ed for 11-12 d, long enough to increase whole body energy metabolism, thus confirming that pathophysiological processes that might involve b rain functions were evolving. Deep brain temperature was also measured in similarly treated rats and found to be mildly elevated relative to core body temperature. Despite the increased deep brain temperature, systemic hypermetabolism, and sympathetic activation, ICMR(glc) was no t elevated in any of the 60 brain structures examined. Average glucose utilization in the brain as a whole was unchanged in the sleep-depriv ed rats, but regional decreases were found. The most marked decreases in ICMR(glc) were in regions of the hypothalamus, thalamus, and limbic system. Mesencephalic and pontine regions were relatively unaffected except for the central gray area. The medulla was entirely normal. The effects of sleep deprivation on brain tended, therefore, to be unidir ectional toward decreased energy metabolism, primarily in regions asso ciated with mechanisms of thermoregulation, endocrine regulation, and sleep. Correspondence was found between the hypometabolic brain region s and some aspects of peripheral symptoms.