Circadian variations in local cerebral glucose utilization in freely moving rats.

Sokoloff's [14C]2-deoxyglucose method has been applied to investigate circadian variations in local cerebral glucose utilization (LCGU). Freely moving rats were tested during two phases of the circadian light/dark cycle. In the rats tested during darkness, elevations in LCGU, when compared with animals tested during the light period, were observed in the primary and secondary visual cortex, the primary auditory cortex, the lateral geniculate nucleus, the amygdala, the entorhinal cortex, the hippocampus, the substantia nigra and the cerebellum. A reduction in LCGU was observed in the suprachiasmatic nucleus.