Expression of diazepam-binding inhibitor peptide in human skin: an immunohistochemical and ultrastructural study

Human diazepam binding inhibitor (DBI) was originally isolated from the brain and subsequently found to be present in several peripheral tissues. The various physiologic effects recently attributed to DBI include acting as an endogenous ligand for the central and peripheral (mitochondrial) benzodiazepine receptors. The present work provides, for the first time, evidence of DBI immunoreactivity in skin. DBI immunoreactivity was found in the epidermis, in the eccrine sweat and in sebaceous glands. Ultrastructurally, DBI was distributed throughout the cytoplasm. Although the physiologic role of DBI in skin is unknown, our results indicate that DBI may serve as an endogenous ligand for mitochondrial benzodiazepine receptors. Its activity could be related to the regulation of lipid and cholesterol synthesis in keratinocytes and sebaceous glands and to the secretion of sweat in sweat glands.