Widespread reductions in cerebral blood flow and metabolism elicited by electrical stimulation of the parabrachial nucleus in rat

We have studied the effect of electrical stimulation of the parabrachial nucleus (PBN) and adjacent areas of dorsal pons on regional cerebral blood flow (rCBF) and glucose utilization (rCGU) in anesthetized (chloralose), paralyzed (tubocurarine) rats. rCBF and rCGU were measured in dissected tissue samples of 9 brain regions by the [ 14C]iodoantipyrine and [ 14C]2-deoxyglucose method, respectively. Electrical stimulation restricted to the medial parabrachial nucleus (PBNm, n=5) elicited significant ( P < 0.05) reductions in rCBF in 7 out of 9 brain regions. Reductions were greatest in cerebral cortex (up to 35% in occipital cortex) and least in the white matter of the corpus callosum (23%). The effect on rCBF persisted after transection of the cervical sympathetic trunk (n=5). In contrast, stimulation of the lateral portion of PBN (n=5), periventricular gray (n=5) and interestingly, the nucleus locus coeruleus (n=5) failed to elicit similar changes in rCBF. PBNm stimulation also elicited decreases in rCGU (n=4) in 5 out of 9 brain areas, most notably regions of cerebral cortex. The decreases in rCGU (ΔrCGU) were linearly related to the decreases in rCBF (ΔrCBF) according to the equationΔrCBF=2.37 ΔrCGU+2.1 (r=0.72; P