Cellular localization of the diazepam binding inhibitor in glial cells with special reference to its coexistence with brain-type fatty acid binding protein.
The diazepam binding inhibitor (DBI) was originally isolated from the brain as an intrinsic ligand of the benzodiazepine binding site on the type-A gamma-aminobutyric acid receptor (GABA(A) receptor). Its wide-spread distribution in non-neural tissues outside the brain suggests that DBI has various functions other than GABA-mediated neurotransmission. Since DBI is identical with the acyl-CoA binding protein, which has the ability to bind long chain acyl-CoA esters, the major function of DBI may possibly be related to lipid metabolism. This idea was supported by our previous study showing the consistent coexpression of DBI and fatty acid binding proteins (FABPs) in epithelia throughout the gastrointestinal tract. The present histochemical study focused on the distribution of DBI in neural tissues, and revealed a definite existence of DBI in non-neuronal supporting cells in both the central and peripheral nervous systems. In the brain, intense immunoreactivity for DBI was detected in the cerebellar Bergmann glia, olfactory ensheathing glia, subgranular layer of the dentate gyrus, and retinal Muller cells. In the peripheral nervous system, satellite cells in sensory/autonomic ganglia, Schwann cells, and sustentacular cells in the adrenal medulla were immunoreactive to a DBI antibody. Moreover, the colocalization of DPI and brain-type FABP (B-FABP) was observed in most of the non-neuronal supporting cells mentioned above, indicating that DBI and B-FABP are cooperatively involved in the energy metabolism of astrocytes and related cells, which are thought to support neuronal development and functions.
Yanase
Haruko
H
Laboratory of Anatomy, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
Shimizu
Hidemi
H
Yamada
Keiko
K
Iwanaga
Toshihiko
T
D000313:Adrenal Medulla / Q000737:chemistry / Q000166:cytology; D000818:Animals; D001253:Astrocytes / Q000166:cytology / Q000378:metabolism; D002352:Carrier Proteins / Q000032:analysis; D002490:Central Nervous System / Q000737:chemistry* / Q000166:cytology; D002831:Choroid Plexus / Q000737:chemistry / Q000166:cytology; D018891:Dentate Gyrus / Q000737:chemistry / Q000166:cytology; D026261:Diazepam Binding Inhibitor / Q000032:analysis*; D004805:Ependyma / Q000737:chemistry / Q000166:cytology; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D005725:Ganglia, Autonomic / Q000737:chemistry / Q000166:cytology; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins; D009457:Neuroglia / Q000737:chemistry*; D009830:Olfactory Bulb / Q000737:chemistry / Q000166:cytology; D017933:Peripheral Nervous System / Q000737:chemistry* / Q000166:cytology; D012160:Retina / Q000737:chemistry / Q000166:cytology; D012583:Schwann Cells / Q000737:chemistry / Q000166:cytology
D002352:Carrier Proteins; D026261:Diazepam Binding Inhibitor; C082667:Fabp5 protein, mouse; C086936:Fabp7 protein, mouse; D000071438:Fatty Acid-Binding Protein 7; D050556:Fatty Acid-Binding Proteins; D009363:Neoplasm Proteins; D009419:Nerve Tissue Proteins