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 densities 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 following portacaval anastomosis (PCA) and in sham-operated control animals. The results demonstrate that densities of H-3-PK11195 binding sites were significantly increased in the cerebral cortex (by 40%, p<0.05) as early as 24 hours following PCA. In the thalamus significant increases in densities of H-3-PK11195 binding sites were seen 3 days after PCA, whereas in brain regions such as the striatum and cerebellum, significant increases in H-3-PK11195 binding sites were not evident until 7 days following PCA. By 28 days following PCA increased densities of H-3-PK11195 binding sites were well established and widespread throughout the brain. Previous studies demonstrate early increases of brain ammonia following PCA. PTBRs or their endogenous ligands could play an important role in the early astrocytic response (mitochondrial proliferation, swelling) to ammonia following PCA.