[Central type benzodiazepine receptor and cerebral blood flow in experimental chronic brain infarction--evaluation...

Double tracer autoradiography was performed to measure regional cerebral blood flow (rCBF) and the binding of central type benzodiazepine receptors (BZR) in infarction by means of permanent occlusion of the unilateral middle cerebral arteries (MCA) in rat. Iodine-125 Iomazenil and 99mTc-HMPAO was used to label BZR and rCBF respectively. In the chronic phase of infarction 21 to 28 days after occlusion (5 rats), rCBF in the left MCA territory was decreased to 62% of the sham control (4 rats), while BZR was more decreased to 45% of the control. In remote areas from the MCA lesion, the ipsilateral thalamus showed 28% decrease of BZR as compared to the control, though the decrease of rCBF was not significant. Iomazenil distribution may represent neuron density or BZR density on a neuron, since central type BZR is reported to be located on neurons. These results suggest that central type BZR imaging is more useful tool for the evaluation of brain tissue viability and transneuronal degeneration than rCBF imaging in brain infarction.