Diazepam binding inhibitor-like immunoreactivity(51-70): distribution in human brain, spinal cord and peripheral tissues.

We have used a specific radioimmunoassay to describe the distribution of diazepam binding inhibitor-like immunoreactivity (DBI-IR(51-70) in human post-mortem tissues. In brain, highest concentrations were found in the cerebellum, amygdala, hippocampus, hypothalamus and substantia nigra. In the spinal cord, DBI-IR(51-70) was evenly distributed. In peripheral tissues, highest concentrations were found in the liver and kidney. Chromatographic analysis revealed several molecular forms of DBI-IR(51-70) the major form being of greater molecular weight and hydrophobicity than the synthetic fragment peptide. In peripheral tissues, but not in the CNS, a small peak of immunoreactivity was indistinguishable from the synthetic peptide. DBI-IR(51-70) is therefore widespread, but tissue processing may be different.