Immunohistochemical assessment of the peripheral benzodiazepine receptor in human tissues

Exhaustive analysis of the location of the peripheral benzodiazepine receptor (PBR) both at the subcellular and the tissue level is warranted to gain a better understanding of its biological roles. To date, many studies have been performed in animal models, such as rat, mouse, and pig, that yielded important information. However, only a few reports were dedicated to the analysis of PBR expression in humans. To enlarge on previous studies, we investigated PBR expression in different human organs using the monoclonal antibody 8D7 that specifically recognized the human PBR. First, we performed electron microscopic analysis that for the first time unambiguously demonstrated the localization of the PBR on the outer mitochondrial membrane. Second, focusing our analysis on human tissues for which information on PBR expression is sparse (lung, stomach, small intestine, colon, thyroid, adrenal gland, pancreas, breast, prostate, ovary), we found that PBR exhibits selective localization. This characterization of PBR localization in human tissues should provide important insights for the understanding of PBR functions.