DIFFERENTIAL VULNERABILITY IN THE HINDBRAIN NEURONS AND LOCAL CEREBRAL BLOOD-FLOW DURING BILATERAL VERTEBRAL OCCLUSION IN GERBILS

Differential vulnerability in the hindbrain neurons was examined immun ohistochemically during hindbrain ischemia in the gerbil. Hindbrain is chemia was produced by extracranial occlusion of the bilateral vertebr al arteries just before their entry into the transverse foramen of the cervical vertebra. Local cerebral blood flow was measured by quantita tive autoradiographic technique after 5 min of ischemia and was reduce d to less than 5 ml/100 g per min in the cerebellum, the pons, and the medulla, indicating that severe and reproducible hindbrain ischemia w as induced immediately after occlusion. For immunohistochemical invest igation, four gerbils each were used for each ischemic period of 5, 10 , 15, and 30 min. Immunohistochemical lesions, detected by the reactio n for microtubule-associated protein 2, were visible in the lateral ve stibular nucleus and the cerebellar interpositus nucleus even after 5 min of ischemia. These results suggested that these areas were more vu lnerable than others, although blood flow was markedly reduced in vari ous regions of the hindbrain. In contrast, areas related to respirator y or cardiovascular control were rather resistant to ischemia. The pre sent study suggests that selective vulnerability during hindbrain isch emia depends mainly on different metabolic characteristics inherent to various neurons in the hindbrain.