Diazepam Binding Inhibitor Expression Research Articles

Octadecaneuropeptide Ameliorates Cognitive Impairments Through Inhibiting Oxidative Stress in Alzheimer's Disease Models.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by amyloid-β peptide (Aβ) deposition. Aβ accumulation induces oxidative stress, leading to mitochondrial dysfunction, apoptosis, and so forth. Octadecaneuropeptide (ODN), a diazepam-binding inhibitor (DBI)-derived peptide, has been reported to have antioxidant properties. However, it is unclear whether ODN has neuroprotective effects in AD. To profile the potential effects of ODN on AD. We established a mouse model of AD via microinjection of Aβ in the lateral ventricle. Utilizing a combination of western blotting assays, electrophysiological recordings, and behavioral tests, we investigated the neuroprotective effects of ODN on AD. DBI expression was decreased in AD model mice and cells. Meanwhile, ODN decreased Aβ generation by downregulating amyloidogenic AβPP processing in HEK-293 cells stably expressing human Swedish mutant APP695 and BACE1 (2EB2). Moreover, ODN could inhibit Aβ-induced oxidative stress in primary cultured cells and mice, as reflected by a dramatic increase in antioxidants and a decrease in pro-oxidants. We also found that ODN could reduce oxidative stress-induced apoptosis by restoring mitochondrial membrane potential, intracellular Ca2+ and cleaved caspase-3 levels in Aβ-treated primary cultured cells and mice. More importantly, intracerebroventricular injection of ODN attenuated cognitive impairments as well as long-term potentiation in Aβ-treated mice. These results suggest that ODN may exert a potent neuroprotective effect against Aβ-induced neurotoxicity and memory decline via its antioxidant effects, indicating that ODN may be a potential therapeutic agent for AD.

Inhibition of vascular endothelial growth factor alleviates neovascular retinopathy with regulated neurotrophic/proinflammatory cytokines through the modulation of DBI-TSPO signaling.

Diazepam binding inhibitor (DBI)-translocator protein (18kDa)(TSPO) signaling in the retina was reported to possess coordinated macroglia-microglia interactions. We investigated DBI-TSPO signaling and its correlation with vascular endothelial growth factor (VEGF), neurotrophic or inflammatory cytokines in neovascular retinopathy, and under hypoxic conditions. The vitreous expression of DBI, VEGF, nerve growth factor (NGF), and interleukin-1beta (IL-1β) were examined in proliferative diabetic retinopathy (PDR) patients with or without anti-VEGF therapy and nondiabetic controls. Retinal DBI-TSPO signaling and the effect of the anti-VEGF agent were evaluated in a mouse model of oxygen-induced retinopathy (OIR). Interactions between Müller cell-derived VEGF and DBI, as well as cocultured microglial cells under hypoxic conditions, were studied, using Western blot, real-time RT-PCR, enzyme-linked immunosorbent assay (ELISA), flow cytometry, and immunofluorescent labeling. Results showed that vitreous levels of DBI, VEGF, NGF, and IL-1β were significantly higher in PDR patients compared with controls, which further changed after anti-VEGF therapy. A statistical association was found between vitreous DBI and VEGF, NGF, IL-1β, and age. The application of the anti-VEGF agent in the OIR model induced retinal expression of DBI and NGF, and attenuated inflammation and microglial cell activation. Inhibition of Müller cell-derived VEGF could increase its DBI expression under hypoxic conditions, while the DBI-TSPO signaling pathway is essential for anti-VEGF agents exerting anti-inflammatory and neuroprotective effects, as well as limiting inflammatory magnitude, promoting its neurotrophin production and anti-inflammatory (M2) polarization in microglial cells. These findings suggest the beneficial effect of anti-VEGF therapy on inflammation and neurotrophy of retinal glial cells through modulation of the DBI-TSPO signaling pathway.

Phenotypic subgrouping and multi-omics analyses reveal reduced diazepam-binding inhibitor (DBI) protein levels in autism spectrum disorder with severe language impairment.

BackgroundThe mechanisms underlying autism spectrum disorder (ASD) remain unclear, and clinical biomarkers are not yet available for ASD. Differences in dysregulated proteins in ASD have shown little reproducibility, which is partly due to ASD heterogeneity. Recent studies have demonstrated that subgrouping ASD cases based on clinical phenotypes is useful for identifying candidate genes that are dysregulated in ASD subgroups. However, this strategy has not been employed in proteome profiling analyses to identify ASD biomarker proteins for specific subgroups.MethodsWe therefore conducted a cluster analysis of the Autism Diagnostic Interview-Revised (ADI-R) scores from 85 individuals with ASD to predict subgroups and subsequently identified dysregulated genes by reanalyzing the transcriptome profiles of individuals with ASD and unaffected individuals. Proteome profiling of lymphoblastoid cell lines from these individuals was performed via 2D-gel electrophoresis, and then mass spectrometry. Disrupted proteins were identified and compared to the dysregulated transcripts and reported dysregulated proteins from previous proteome studies. Biological functions were predicted using the Ingenuity Pathway Analysis (IPA) program. Selected proteins were also analyzed by Western blotting.ResultsThe cluster analysis of ADI-R data revealed four ASD subgroups, including ASD with severe language impairment, and transcriptome profiling identified dysregulated genes in each subgroup. Screening via proteome analysis revealed 82 altered proteins in the ASD subgroup with severe language impairment. Eighteen of these proteins were further identified by nano-LC-MS/MS. Among these proteins, fourteen were predicted by IPA to be associated with neurological functions and inflammation. Among these proteins, diazepam-binding inhibitor (DBI) protein was confirmed by Western blot analysis to be expressed at significantly decreased levels in the ASD subgroup with severe language impairment, and the DBI expression levels were correlated with the scores of several ADI-R items.ConclusionsBy subgrouping individuals with ASD based on clinical phenotypes, and then performing an integrated transcriptome-proteome analysis, we identified DBI as a novel candidate protein for ASD with severe language impairment. The mechanisms of this protein and its potential use as an ASD biomarker warrant further study.

Neuroprotection with the Endozepine Octadecaneuropeptide, ODN

The term endozepines designates a family of astroglia-secreted proteins including the diazepambinding inhibitor (DBI) and its processing products, which have been originally isolated and characterized as endogenous ligands of benzodiazepine receptors. It is now clearly established that the octadecaneuropeptide ODN (DBI33-50), acting through the central-type benzodiazepine receptor or a metabotropic receptor, exerts important functions such as proconflict behavior, induction of anxiety, inhibition of pentobarbital-provoked sleep, decrease of water consumption and reduction of food intake. To mediate its effects, ODN regulates both glial cell and neuronal activities by acting on neurosteroid biosynthesis and/or neuropeptide expression. In addition, ODN stimulates astrocyte proliferation and protects both neurons and astrocytes from oxidative stress-induced cell death. The antiapoptotic effect of ODN on neural cells is mediated through activation of the ODN metabotropic receptor positively coupled to PKA, PKC and MAPK/ERK transduction pathways, which ultimately reduces the pro-apoptotic gene Bax and stimulates Bcl-2 expressions, and inhibits intracellular reactive oxygen species accumulation. The imbalance in favor of Bcl2 promotes mitochondria functions and blocks in turn caspases activation while at the same time, ODN also activates the endogenous antioxidant system i.e. glutathione biosynthesis, and expression and activities of antioxidant enzymes. In cultured astrocytes, DBI expression is up-regulated during moderate oxidative stress, and authentic ODN production is increased, suggesting that ODN may act as a paracrine factor protecting neighboring neurons. Taken together, the remarkable effect of ODN on the apoptotic cascade suggests that innovative ODN derivatives could potentially be useful for treatment of cerebral injuries involving oxidative stress and neurodegeneration.

PARADOXICAL EFFECTS OF NOTCH SIGNALING IN RESPONSE TO ENVIRONMENTAL ENRICHMENT DURING CRITICAL PERIOD: MOLECULAR MECHANISM UNDERLYING COGNITIVE RESERVE?

Background: Adult neurogenesis and hippocampal function are both regulated by neuronal activity, particularly by GABAergic signals. Recently, it has been reported that an imbalance of the GABAergic ~a transmission impairs adult neurogenesis in Alzheimer’s disease (AD). This GABAergic signal is modulated by several endogenous molecules. Diazepam binding inhibitor is a small cytosolic polypeptide which is an inverse agonist of GABA A receptor. Thus, we researched the expression and the effect of diazepam binding inhibitor (DBI) on neurogenesis in the hippocampus by using AD model mice. Methods: In this study, we used AD model mice which the early onset of the symptoms of AD was induced. Our recent study showed that feeding with High Fat Diet is a viable method for inducing the early onset of the symptoms of AD in B6C3-Tg (APPswe/PSEN1dE9)85Dbo/J Alzheimer’s Disease Model Transgenic mice. Using these mice, we performed DBI knockdown experiment and immunostaing of DBI to investigate a functional role of DBI in dentate gyrus. To evaluate the effect of DBI knockdown for differentiation we observed the number and morphology of doublecortin (DCX; immature neuron marker) positive cells. Results: We immunostained DBI and dyed senile plaques to compare the expression of DBI in AD model and control mice. As a result, we observed a tendency of increased DBI expression in the hippocampus in AD model mice. Commonly, DBI is expressed in neural stem cells, however, it was also expressed in glial cell in AD model mice. Furthermore, expression of DBI was observed in astrocytes surrounding senile plaques in AD model mice. This result corroborates the report that the Ab peptide stimulates DBI biosynthesis in cultured rat astrocytes. The impairment of maturation of immature neuron in AD model mice was repaired by the inhibition of DBI expression in the dentate gyrus. Conclusions: These results suggest that increased DBI in the hippocampus inhibit normal maturation in AD model mice. This increased DBI is derived from astrocyte activated by Ab. DBI produced by astrocyte and released in the dentate gyrus cause disorder in neurogenesis in AD mice via GABA A receptor.

Gliotransmission and Brain Glucose Sensing

Hypothalamic glucose sensing is involved in the control of feeding behavior and peripheral glucose homeostasis, and glial cells are suggested to play an important role in this process. Diazepam-binding inhibitor (DBI) and its processing product the octadecaneuropeptide (ODN), collectively named endozepines, are secreted by astroglia, and ODN is a potent anorexigenic factor. Therefore, we investigated the involvement of endozepines in brain glucose sensing. First, we showed that intracerebroventricular administration of glucose in rats increases DBI expression in hypothalamic glial-like tanycytes. We then demonstrated that glucose stimulates endozepine secretion from hypothalamic explants. Feeding experiments indicate that the anorexigenic effect of central administration of glucose was blunted by coinjection of an ODN antagonist. Conversely, the hyperphagic response elicited by central glucoprivation was suppressed by an ODN agonist. The anorexigenic effects of centrally injected glucose or ODN agonist were suppressed by blockade of the melanocortin-3/4 receptors, suggesting that glucose sensing involves endozepinergic control of the melanocortin pathway. Finally, we found that brain endozepines modulate blood glucose levels, suggesting their involvement in a feedback loop controlling whole-body glucose homeostasis. Collectively, these data indicate that endozepines are a critical relay in brain glucose sensing and potentially new targets in treatment of metabolic disorders.

Expression of diazepam binding inhibitor in neural stem cells of the dentate gryus

Expression of diazepam binding inhibitor in neural stem cells of the dentate gryus

Diazepam Enhances Production of Diazepam-Binding Inhibitor (DBI), a Negative Saliva Secretion Regulator, Localized in Rat Salivary Gland

Peripheral-type benzodiazepine receptor (PBR) and central-type benzodiazepine receptor (CBR) in salivary gland play a role in the inhibitory regulation of salivary secretion in rodents. Diazepam-binding inhibitor (DBI), an endogenous ligand for PBR, produces neurosteroids, which modulate CBR activity. In this study, we investigated the effect of repetitive administration of diazepam (DZP) on salivary secretion and expression of DBI mRNA and peptide. Moreover, mRNA expression of PBR and pituitary adenylate cyclase–activating polypeptide (PACAP), a transcriptional regulator for DBI promoter, was evaluated after repetitive administration of DZP. Repetitive administration, but not single administration, of 0.4 mg/kg DZP caused inhibition of salivary secretion and enhanced expression of DBI, PACAP, and PBR mRNA in rat salivary gland, with an increase in production of DBI peptide. These results suggest that repetitive administration of DZP stimulates DBI production, which may result in an increase in the suppressive effect of DZP on salivary secretion.

Acute food deprivation reduces expression of diazepam-binding inhibitor, the precursor of the anorexigenic octadecaneuropeptide ODN, in mouse glial cells

In the central nervous system of mammals, the gene encoding diazepam-binding inhibitor (DBI) is exclusively expressed in glial cells. Previous studies have shown that central administration of a DBI processing product, the octadecaneuropeptide ODN, causes a marked inhibition of food consumption in rodents. Paradoxically, however, the effect of food restriction on DBI gene expression has never been investigated. Here, we show that in mice, acute fasting dramatically reduces DBI mRNA levels in the hypothalamus and the ependyma bordering the third and lateral ventricles. I.p. injection of insulin, but not of leptin, selectively stimulated DBI expression in the lateral ventricle area. These data support the notion that glial cells, through the production of endozepines, may relay peripheral signals to neurons involved in the central regulation of energy homeostasis.

Genoproteomic Mining of Urothelial Cancer Suggests γ-Glutamyl Hydrolase and Diazepam-Binding Inhibitor as Putative Urinary Markers of Outcome after Chemotherapy

Urinary biomarkers for the detection of bladder cancer have been developed, but no similar markers exist for prediction of clinical outcomes after receiving chemotherapy. Here we evaluate an approach that combines genomic, proteomic, and therapeutic outcome datasets to identify novel putative urinary biomarkers of clinical outcome after neoadjuvant methotrexate, vinblastine, doxorubicin, and cisplatin (MVAC). Using this method, we identified gamma-glutamyl hydrolase (GGH), emmprin, survivin, and diazepam-binding inhibitor (DBI). Interestingly, GGH is a protein associated with methotrexate resistance, whereas emmprin, survivin, and DBI had been previously identified as predictors of outcome after platinum-containing chemotherapeutic regimens when assessed on tumor tissue. Using disease-free survival as a marker for clinical outcome, we evaluated the ability of GGH, emmprin, survivin, and DBI expression in tumor tissue to stratify 27 patients treated with neoadjuvant MVAC. DBI (P = 0.046) but not GGH (P = 0.190), emmprin (P = 0.066), or survivin (P = 0.393) successfully stratified patients. When GGH was used with DBI the significance of stratification improved (P = 0.024), whereas the addition of survivin or emmprin to this latter two-gene model reduced its significance (P = 0.036 and P = 0.040, respectively). Although these predictive results were obtained on tumor tissues, the presence of GGH and DBI in urine serves as a rationale for developing them as urinary markers of clinical outcomes for patients treated with neoadjuvant MVAC.

Aged Alzheimer mice bear the increased expression of diazepam binding inhibitor in activated glial cells

Aged Alzheimer mice bear the increased expression of diazepam binding inhibitor in activated glial cells

Increase in diazepam binding inhibitor expression by sustained morphine exposure is mediated via μ‐opioid receptors in primary cultures of mouse cerebral cortical neurons

Our previous in vivo experiment demonstrates that chronic morphine treatment up-regulates diazepam binding inhibitor (DBI) transcripts in mouse cerebral cortex, although detailed mechanisms were unclear (Katsura et al. [1998] J. Neurochem. 71:2638-2641). This study sought to elucidate the precise mechanisms of DBI mRNA up-regulation by long-term treatment with morphine using primary cultures of mouse cerebral cortical neurons. A significant increase in DBI mRNA was observed after sustained exposure to 0.3 microM morphine for 2 days, and the maximal expression occurred after 2 days of exposure, whereas transient exposure to 0.3 microM morphine for 15 min, 1 hr, and 3 hr produced no changes in the expression. Continuous exposure to DAMGO also significantly increased DBI mRNA expression, which was completely abolished by a selective antagonist of mu-opioid receptors, beta-funaltrexamine (beta-FNA). The morphine-induced increase in DBI mRNA expression and its content were completely inhibited by naloxone and beta-FNA, and the inhibitory potential of naloxonazine was about half that of beta-FNA. On the other hand, kappa- and delta-opioid receptor antagonists showed no effects on the morphine-induced increase in DBI mRNA. In addition, both a calmodulin antagonist and a CaM II kinase inhibitor significantly suppressed the morphine-induced increase in DBI mRNA. These results indicate that the increase in DBI expression is induced by continuous activation of mu-opioid receptors but not of kappa- and delta-opioid receptors and is regulated by the calcium/calmodulin-related phosphorylation system.

Expressions of diazepam binding inhibitor in some selected brain regions of chronic morphine dependent rats at different time-points

目的 研究地西泮结合抑制因子(DBI)基因在慢性吗啡依赖大鼠部分脑区不同时点表达水平的变化.方法30只雄性SD大鼠随机分为研究组20只和生理盐水对照组10只.研究组:腹腔注射盐酸吗啡,2次/d,起始剂量为5 mg·kg-1·次-1,逐日递增5 mg·kg-1·次-1,至第10天为50 mg·kg-1·次-1,对照组同期注射相同体积的生理盐水.研究组于末次注射后3 h(依赖组)及72h(戒断3 d组)、第6天(戒断6 d组)、第10天(戒断10 d组)分别处死5只,对照组于末次注射后3h及72h分别各处死5只,灌注、取脑、冰冻切片并选取含有海马CA1区(HIPCA1)、中脑腹侧被盖区(VTA)、伏隔核(Nac)、前额叶皮质(PFC)、杏仁核(AMG)、中脑导水管(PAG)等结构的脑片,利用组织原位杂交技术检测DBI mRNA在各脑区的表达,进行组间比较.结果 吗啡成瘾组在HIPCA1、VTA、Nac、PFC、AMG、PAG和LC的DBI mRNA表达依次为:102.7±6.7、139.6±12.8、137.1±9.3、144.3±10.8、153.6±10.6、122.1±8.5和100.0±8.8,显著高于对照组,并均在戒断的第3天达到峰值,依次为139.7±12.4、181.1±10.2、159.3±13.3、186.6±7.6、195.1±7.0、176.9±14.7,随后出现下调,在戒断第6天各脑区仍高于对照组,在戒断第10天,除了 PFC仍为145.3±9.3,明显高于对照组(P <0.05)外,其他脑区与对照组无显著差异.结论DBIm RNA在慢性吗啡处理大鼠部分脑区的表达上调,可能参与了慢性吗啡依赖过程。

Conditioned place preference associates with the mRNA expression of diazepam binding inhibitor in brain regions of the addicted rat during withdrawal

The diazepam binding inhibitor (DBI) modulating the functions of the GABAA receptors is involved in the maladaptation of neural system during using opiate, but its role in opiate dependence is not fully understood. Using conditioned place preference (CPP) rat model and in situ hybridization technique, we examined the correlation between opiate dependence and the mRNA expression of DBI. We found that chronic morphine treatment enabled CPP and increased the DBI mRNA expression in crucial brain regions of addiction. Withdrawal for 3 days caused significant physical signs and further increased the DBI mRNA expression. Both the DBI mRNA and CPP expression remained significantly high but physical signs were at control level in the animals withdrawal for 6 days. Remarkably, the DBI mRNA expressions in the CA1 region of the hippocampus (CA1), ventral tagmental area (VTA), nucleus accumbens (NAc) and amygdala (AMG) were positively correlated to CPP during the periods from withdrawal for 3 days to withdrawal for 6 days. These findings suggest that DBI may play a role in both physical and psychological dependence of opiates.

Functional Proteins Involved in Regulation of Intracellular Ca2+ for Drug Development: Chronic Nicotine Treatment Upregulates L-Type High Voltage-Gated Calcium Channels

Neurochemical mechanisms underlying drug dependence and withdrawal syndrome remain unclear. In this review, we discuss how chronic nicotine exposure to neurons affects expression of diazepam binding inhibitor (DBI), an endogenous anxiogenic neuropeptide supposed to be a common substance participating drug dependence, and function of L-type high voltage-gated Ca2+ channels (HVCCs). We also discuss the functional interaction between DBI and L-type HVCCs in nicotine dependence. Both DBI levels and [45Ca2+] influx significantly increased in the brain from mice treated with nicotine for long term, which was further enhanced after abrupt cessation of nicotine and was abolished by nicotinic acetylcholine receptor (nAChR) antagonists. Similar responses of DBI expression and L-type HVCC function were observed in cerebral cortical neurons after sustained exposure to nicotine. In addition, increased DBI expression was inhibited by antagonists of nAChR and L-type HVCCs. Sustained exposure of neurons to nicotine significantly enhanced expression of α1 and α2/δ1 subunits for L-type HVCCs and caused an increase in the Bmax value of [3H]verapamil binding to the particulate fractions. Therefore, it is concluded that the alterations in DBI expression is mediated via increased influx of Ca2+ through upregulated L-type HVCCs and these neurochemical changes have a close relationship with development of nicotine dependence and/or its withdrawal syndrome.

Pharmacological Basis for Management of Drug Dependence

Neurochemical mechanisms underlying development of drug dependence and withdrawal syndrome remain unclear. Several clinical features of withdrawal syndrome, such as anxiety, are considered to be common among patients with drug dependence induced by different drugs of abuse. In the present study, we investigated whether diazepam-binding inhibitor (DBI), an endogenous anxiogenic neuropeptide, participates in the anxiety associated with drug dependence and its withdrawal symptoms. When we examined brain from mice dependent on alcohol, nicotine, and morphine, we observed that the levels of DBI protein and its mRNA significantly increased. Abrupt cessation of these drugs facilitated further increases in DBI expression. In the cases of nicotine- and morphine-dependent mice, concomitant administration of specific antagonists for nicotinic acetylcholine and m-opioid receptors, respectively, abolished the increased expression. Similar patterns of DBI expression were observed in the neurons after sustained exposure to these drugs and its removal from culture medium. Sustained exposure of the neurons to abused drugs significantly increased the KCl (30 mM)-induced 45Ca2+ influx and enhanced expression of alpha1 subunits for L-type high voltage-gated Ca2+ channels (HVCCs). In addition, the increase in DBI expression was completely blocked by L-type HVCC inhibitors. Therefore, these alterations in DBI expression, mediated via increased influx of Ca2+ through upregulated L-type HVCCs, are closely related to drug dependence and/or its withdrawal syndrome and are considered to be part of a common biochemical process in drug dependence induced by different drugs of abuse.

NMDA receptor activation enhances diazepam binding inhibitor and its mRNA expressions in mouse cerebral cortical neurons

Effects of N-methyl- d-aspartate (NMDA) on diazepam binding inhibitor (DBI) and its mRNA expression in mouse cerebral cortical neurons were examined. A significant increase in DBI mRNA expression was observed 1 day after the exposure to 0.1 μM NMDA and the maximal expression occurred 2 days after the exposure, whereas transient exposure to 0.1 μM NMDA for 15 min, 1 and 3 h produced no changes in the expression. Similarly, no changes in the expression were found by the concomitant exposure to NMDA and MK-801, a NMDA receptor antagonist, for 72 h subsequent to the incubation with NMDA alone for 3 h. Such NMDA-induced increases in DBI mRNA expression were dose-dependently inhibited by MK-801. Moreover, neuronal DBI content significantly increased by treatment with NMDA, which was completely abolished by MK-801. These results indicate that continuous activation of NMDA receptors is an essential factor for increasing DBI expression in the neurons.

Functional involvement of cerebral diazepam binding inhibitor (DBI) in the establishment of drug dependence

Mechanisms for formation of drug dependence and emergence of withdrawal syndrome are not yet fully understood despite of a huge accumulation of experimental and clinical data. Several clinical features of withdrawal syndrome are considered to be common (i.e., anxiety) among patients with drug dependence induced by different drugs of abuse. In this review, we have discussed the possibility of the functional involvement of diazepam binding inhibitor (DBI), an endogenous neuropeptide for benzodiazepine receptors with endogenously anxiogenic potential, in the development of drug dependence and emergence of its withdrawal symptom. The levels of DBI protein and its mRNA significantly increased in the brain derived from mice dependent on alcohol (ethanol), nicotine and morphine, and abrupt cessation of these drugs facilitated further increase in DBI expression. In the cases of nicotine- and morphine-dependent mice, concomitant administration of antagonists for nicotinic acetylcholine and opioid receptors, respectively, abolished the increase in DBI expression. Therefore, these alterations in DBI expression have a close relationship with formation of drug dependence and/or emergence of withdrawal syndrome and are considered to be a common biochemical process in drug dependence induced by different drugs of abuse.

Increased expression of peripheral benzodiazepine receptors and diazepam binding inhibitor in human tumors sited in the liver

The peripheral benzodiazepine receptor system triggers intracellular metabolic events and has been associated with cell proliferation. Its endogenous ligand, the diazepam binding inhibitor, contributes to steroidogenesis by promoting cholesterol delivery to the inner mitochondrial membrane. The present study was undertaken to verify whether this system is altered in tumors sited in the liver. Peripheral benzodiazepine receptors and diazepam binding inhibitor were studied using immunocytochemistry and in situ hybridization in 9 human tumors sited in the liver, in liver hyperplasia, cirrhotic nodular regeneration, intestinal adenocarcinoma and in surrounding non-tumoral tissue. Immunocytochemical staining and in situ hybridization demonstrated that peripheral benzodiazepine receptors and diazepam binding inhibitor were more prominently expressed in neoplastic cells than in non-tumoral tissue. They were present in the same cells, suggesting that diazepam binding inhibitor may act in an intracrine manner in these cells. Higher peripheral benzodiazepine receptors and diazepam binding inhibitor expression in tumor cells suggest an implication of this system in the metabolism of neoplastic cells. Furthermore the evaluation of peripheral benzodiazepine receptor and diazepam binding inhibitor expression might be useful in evaluating malignancy and in diagnostic approaches of tumors in liver tissue.

Continuous treatment with morphine increases diazepam binding inhibitor mRNA in mouse brain.

Effects of acute and chronic morphine treatment on the expression of diazepam binding inhibitor (DBI) mRNA in the mouse brain were examined. Cerebral DBI mRNA expression significantly increased in morphine-dependent mice, and this increase is more remarkable in morphine-withdrawn mice, whereas a single administration of morphine (50 mg/kg) produced no changes in the expression. Simultaneous administration of naloxone (3 mg/kg) with morphine completely abolished the increase in cerebral DBI mRNA expression observed in morphine-dependent and -withdrawn mice. These results indicate that a chronic functional interaction between morphine and opioid receptors has a critical role in increases in DBI mRNA expression.