Effect of stimulation of facial nerve on regional cerebral blood flow and glucose utilization in cats.

Regional cerebral blood flow was determined using the tracer [14C]iodoantipyrine and regional brain dissection, and regional cerebral glucose utilization was determined using the 2-deoxyglucose method in the alpha-chloralose-anesthetized cat to evaluate the effect of electrical stimulation of the facial nerve. The nerve was sectioned intracranially to isolate it from the brain stem and the distal portion stimulated before entry into the internal auditory meatus. Stimulation led to a global increase in cortical (frontal, parietal, temporal, occipital, and cingulate cortex) and white matter blood flow. This effect was predominantly ipsilateral to the side stimulated, although significant effects were also noted on the contralateral side. The latter were confined to the more anterior cortical structures. In contrast, there were no significant changes in regional metabolic activity as assessed by the rate of glucose utilization. This study provides direct evidence for a neurogenic vasodilator effect of activation of the facial-greater superficial petrosal pathway that is independent of regional brain metabolic activity.