Exercise-Induced Changes in Local Cerebral Glucose Utilization in the Rat

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Abstract
In exercise, little is known about local cerebral glucose utilization (LCGU), which is an index of functional neurogenic activity. We measured LCGU in resting and running (≈85% of maximum O2 uptake) rats (n = 7 in both groups) previously equipped with a tail artery catheter. LCGU was measured quantitatively from 2-deoxy-D-[1-14C]glucose autoradiographs. During exercise, total cerebral glucose utilization (TCGU) increased by 38% (p < 0.005). LCGU increased (p < 0.05) in areas involved in motor function (motor cortex 39%, cerebellum ≈110%, basal ganglia ≈30%, substantia nigra ≈37%, and in the following nuclei: subthalamic 47%, posterior hypothalamic 74%, red 61%, ambiguus 43%, pontine 61%), areas involved in sensory function (somatosensory 27%, auditory 32%, and visual cortex 42%, thalamus ≈75%, and in the following nuclei: Darkschewitsch 22%, cochlear 51%, vestibular 30%, superior olive 23%, cuneate 115%), areas involved in autonomic function (dorsal raphe nucleus 30%, and areas in the hypothalamus ≈35%, amygdala ≈35%, and hippocampus 29%), and in white matter of the corpus callosum (36%) and cerebellum (52%). LCGU did not change with exercise in prefrontal and frontal cortex, cingulum, inferior olive, nucleus of solitary tract and median raphe, lateral septal and interpenduncular nuclei, or in areas of the hippocampus, amygdala, and hypothalamus. Glucose utilization did not decrease during exercise in any of the studied cerebral regions. In summary, heavy dynamic exercise increases TCGU and evokes marked differential changes in LCGU. The findings provide clues to the cerebral areas that participate in the large motor, sensory, and autonomic adaptation occurring in exercise.