DENSITIES OF BINDING-SITES FOR THE PERIPHERAL-TYPE BENZODIAZEPINE RECEPTOR-LIGAND H-3 PK11195 ARE INCREASED IN BRAIN 24 HOURS FOLLOWING PORTACAVAL ANASTOMOSIS

Quantitative receptor autoradiography was used to measure the densitie s of binding sites for the ''peripheral-type'' benzodiazepine receptor ligand H-3-PK11195 in regions of the rat brain 1, 3, 7 and 28 days fo llowing portacaval anastomosis (PCA) and in sham-operated control anim als. The results demonstrate that densities of H-3-PK11195 binding sit es were significantly increased in the cerebral cortex (by 40%, p<0.05 ) as early as 24 hours following PCA. In the thalamus significant incr eases in densities of H-3-PK11195 binding sites were seen 3 days after PCA, whereas in brain regions such as the striatum and cerebellum, si gnificant increases in H-3-PK11195 binding sites were not evident unti l 7 days following PCA. By 28 days following PCA increased densities o f H-3-PK11195 binding sites were well established and widespread throu ghout the brain. Previous studies demonstrate early increases of brain ammonia following PCA. PTBRs or their endogenous ligands could play a n important role in the early astrocytic response (mitochondrial proli feration, swelling) to ammonia following PCA.