Effect of oxotremorine on local cerebral glucose utilization in motor system regions of the rat brain.

The [14C]2-deoxy-D-glucose technique was used to test the effects of central muscarinic stimulation on local cerebral glucose utilization (LCGU) in rats. Systemic administration of the muscarinic agonist oxotremorine (OXO, 0.7 mg/kg, ip) increased LCGU in brain regions involved in motor function: the sensorimotor cortex; the extrapyramidal motor system, including the striatum, globus pallidus, red nucleus, substantia nigra, subthalamus and ventral nucleus of the thalamus; the cerebellar vermis, fastigial nucleus and nucleus interpositus; and the vestibular nucleus. No effects were observed in the fibers of the pyramidal tract, internal capsule, cerebellar white matter and the dentate nucleus. Increases were not affected by methylatropine (1 mg/kg sc), but were completely antagonized by scopolamine (2.5 mg/kg, ip). The anatomic distribution and magnitude of the LCGU response to OXO were not simply correlated with the reported densities of muscarinic receptors.