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Pharmacol Ther. 2019 Jul 5:107386. doi: 10.1016/j.pharmthera.2019.06.008. [Epub ahead of print]

Endozepines and their receptors: Structure, functions and pathophysiological significance.

Author information

1
Normandy University, Neuronal and Neuroendocrine Differentiation and Communication, Inserm, U1239 Rouen, France.
2
Normandy University, Neuronal and Neuroendocrine Differentiation and Communication, Inserm, U1239 Rouen, France; Normandy University, Regional Platform for Cell Imaging of Normandy (PRIMACEN), Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France. Electronic address: hubert.vaudry@univ-rouen.fr.
3
Aix Marseille University, Cognitive Neuroscience Laboratory (LNC), UMR CNRS, 7291 Marseille, France.
4
McGill University, The Research Institute of the McGill University Health Centre and Department of Medicine, Montreal, Quebec, Canada.
5
University Tunis El Manar, Faculty of Sciences of Tunis, LR18ES03, Laboratory of Neurophysiology, Cellular Physiopathology and Biomolecule Valorisation, Tunis, Tunisia.
6
Normandy University, Neuronal and Neuroendocrine Differentiation and Communication, Inserm, U1239 Rouen, France; Normandy University, Regional Platform for Cell Imaging of Normandy (PRIMACEN), Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France.
7
University of Lille, Development and Plasticity of the Neuroendocrine Brain, Inserm, U1172, CHU Lille, School of Medicine, Lille, France.
8
McGill University, The Research Institute of the McGill University Health Centre and Department of Medicine, Montreal, Quebec, Canada; University of Southern California, Department of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, Los Angeles, CA, United States of America.
9
Normandy University, Neuronal and Neuroendocrine Differentiation and Communication, Inserm, U1239 Rouen, France; Normandy University, Regional Platform for Cell Imaging of Normandy (PRIMACEN), Institute for Research and Innovation in Biomedicine (IRIB), Rouen, France. Electronic address: jerome.leprince@univ-rouen.fr.

Abstract

The existence of specific binding sites for benzodiazepines (BZs) in the brain has prompted the search for endogenous BZ receptor ligands designated by the generic term « endozepines ». This has led to the identification of an 86-amino acid polypeptide capable of displacing [3H]diazepam binding to brain membranes, thus called diazepam-binding inhibitor (DBI). It was subsequently found that the sequence of DBI is identical to that of a lipid carrier protein termed acyl-CoA-binding protein (ACBP). The primary structure of DBI/ACBP has been well preserved, suggesting that endozepines exert vital functions. The DBI/ACBP gene is expressed by astroglial cells in the central nervous system, and by various cell types in peripheral organs. Endoproteolytic cleavage of DBI/ACBP generates several bioactive peptides including a triakontatetraneuropeptide that acts as a selective ligand of peripheral BZ receptors/translocator protein (PBR/TSPO), and an octadecaneuropeptide that activates a G protein-coupled receptor and behaves as an allosteric modulator of the GABAAR. Although DBI/ACBP is devoid of a signal peptide, endozepines are released by astrocytes in a regulated manner. Consistent with the diversity and wide distribution of BZ-binding sites, endozepines appear to exert a large array of biological functions and pharmacological effects. Thus, intracerebroventricular administration of DBI or derived peptides induces proconflict and anxiety-like behaviors, and reduces food intake. Reciprocally, the expression of DBI/ACBP mRNA is regulated by stress and metabolic signals. In vitro, endozepines stimulate astrocyte proliferation and protect neurons and astrocytes from apoptotic cell death. Endozepines also regulate neurosteroid biosynthesis and neuropeptide expression, and promote neurogenesis. In peripheral organs, endozepines activate steroid hormone production, stimulate acyl chain ceramide synthesis and trigger pro-inflammatory cytokine secretion. The expression of the DBI/ACBP gene is enhanced in addiction/withdrawal animal models, in patients with neurodegenerative disorders and in various types of tumors. We review herein the current knowledge concerning the various actions of endozepines and discusses the physiopathological implications of these regulatory gliopeptides.

KEYWORDS:

Acyl-CoA-binding protein; Benzodiazepines; Diazepam-binding inhibitor; Octadecaneuropeptide; Translocator protein; Triakontatetraneuropeptide

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