Subarachnoid Hemorrhage in the Rat: Cerebral Blood Flow and Glucose Metabolism after Selective Lesions of the Catecholamine Systems in the Brainstem

A double-isotope autoradiographic technique was used to evaluate CBF and glucose metabolism 2 days after a subarachnoid hemorrhage (SAH) in rats with lesions in the lower brainstem. Lesioning in the mesencephalon of the ascending catecholamine pathways from locus ceruleus and from the A₁ and A₂ nuclei, or lesioning in the medulla oblongata of the ascending fibers from A₁ and A₂, prevents the development of the global changes in flow and metabolism seen in normal animals post SAH. Also the focal low-flow areas with markedly elevated deoxyglucose uptake, which can develop in normal animals 2 days post SAH, were not seen in the lesioned animals after the SAH. The findings indicate that the A₁ and A₂ nuclei, which project to the hypothalamus–pituitary, are essential for the flow and metabolic changes after an SAH. The lesions per se did not change baseline flow and metabolism as compared with sham-lesioned animals.