Benzodiazepine receptors and diazepam binding inhibitor: a possible link between stress, anxiety and the immune system

The Triad of Sleep, Immunity, and Cancer: A Mediating Perspective

The triadic interplay between sleep, immunity, and cancer represents a growing area of biomedical research with significant clinical implications. This review synthesizes the current knowledge on how sleep influences immune function, the immune system's role in cancer dynamics, and the direct connections between sleep patterns and cancer risk. After a comprehensive overview of the interrelationships among these three domains, the mechanisms of sleep in immune function are described, detailing how sleep regulates the immune system, the effects of sleep duration and quality on immune responses, and the underlying molecular and cellular mechanisms. Also, the complex relationship between immunity and cancer is explored, highlighting the immune system's role in cancer prevention and progression, immune surveillance, tumor microenvironment, and the implications of immunodeficiency and immune modulation on cancer risk. The direct connections between sleep and cancer are then described, presenting epidemiological evidence linking sleep patterns to cancer risk, biological mechanisms that influence cancer development, and the role of sleep disorders in cancer prognosis. The mediating role of sleep between immunity and cancer is highlighted, proposing hypothesized pathways, summarizing evidence from experimental and clinical studies, and evaluating the impact of sleep interventions on immune function and cancer outcomes. This review concludes by discussing the clinical implications and future directions, emphasizing the potential for sleep-based interventions in cancer prevention and treatment, the integration of sleep management in oncology and immunotherapy, and outlining a future research agenda. This agenda includes understanding the mechanisms of the sleep-immunity-cancer interplay, conducting epidemiological studies on sleep and cancer risk, assessing the impact of sleep management in cancer treatment protocols, exploring sleep and tumor microenvironment interactions, and considering policy and public health implications. Through a detailed examination of these interconnected pathways, this review underscores the critical importance of sleep in modulating immune function and cancer outcomes, advocating for interdisciplinary research and clinical strategies to harness this knowledge for improved health outcomes.

Pharmacotherapeutic management of insomnia and effects on sleep processes, neural plasticity, and brain systems modulating stress: A narrative review

Introduction

Insomnia is a stress-related sleep disorder, may favor a state of allostatic overload impairing brain neuroplasticity, stress immune and endocrine pathways, and may contribute to mental and physical disorders. In this framework, assessing and targeting insomnia is of importance.

Aim

Since maladaptive neuroplasticity and allostatic overload are hypothesized to be related to GABAergic alterations, compounds targeting GABA may play a key role. Accordingly, the aim of this review was to discuss the effect of GABAA receptor agonists, short-medium acting hypnotic benzodiazepines and the so called Z-drugs, at a molecular level.

Method

Literature searches were done according to PRISMA guidelines. Several combinations of terms were used such as “hypnotic benzodiazepines” or “brotizolam,” or “lormetazepam” or “temazepam” or “triazolam” or “zolpidem” or “zopiclone” or “zaleplon” or “eszopiclone” and “insomnia” and “effects on sleep” and “effect on brain plasticity” and “effect on stress system”. Given the complexity and heterogeneity of existing literature, we ended up with a narrative review.

Results

Among short-medium acting compounds, triazolam has been the most studied and may regulate the stress system at central and peripheral levels. Among Z-drugs eszopiclone may regulate the stress system. Some compounds may produce more “physiological” sleep such as brotizolam, triazolam, and eszopiclone and probably may not impair sleep processes and related neural plasticity. In particular, triazolam, eszopiclone, and zaleplon studied in vivo in animal models did not alter neuroplasticity.

Conclusion

Current models of insomnia may lead us to revise the way in which we use hypnotic compounds in clinical practice. Specifically, compounds should target sleep processes, the stress system, and sustain neural plasticity. In this framework, among the short/medium acting hypnotic benzodiazepines, triazolam has been the most studied compound while among the Z-drugs eszopiclone has demonstrated interesting effects. Both offer potential new insight for treating insomnia.

The cross-sectional association of frailty with chronic past and current use of benzodiazepine drugs

BACKGROUND

Frailty, a clinical syndrome characterized by vulnerability to stressors resulting from multisystemic loss of physiological reserve. The use of benzodiazepines in older adults has been associated with confusion, sedation, and cognitive impairment, which in turn may lead to frailty.

AIMS

The purpose of this study was to determine the cross-sectional association between frailty and chronic past or current use of benzodiazepine drugs among older US Veterans.

METHODS/DESIGN

This is a cross-sectional study of community-dwelling older Veterans who had determinations of frailty. Benzodiazepine prescription data were obtained via EHR. A 31-item VA Frailty Index (VA-FI) was generated at the time of the assessment. We categorized Veterans into robust (FI ≤ 0.10), pre-frail (FI 0.10-0.21), and Frail (FI ≥ 0.21). After adjusting for sociodemographic characteristics, we calculated ORs and 95% CIs using a binomial logistic regression (BLR) model to assess the cross-sectional association between benzodiazepine use and frailty.

RESULTS

Population sample consisted of 17,423 Veterans, mean age 75.53 (SD = 8.03) years, 70.80% Caucasian, 97.34% male, 14,545 (83.50%) patients were non-users of benzodiazepine drugs, 2408 (13.80%) had a past use, and 470 (2.70%) were current users. In BLR, individuals with past (OR 2.51, 95% CI 2.30-2.74, p < .001) or current (OR 2.36, 95% CI 1.96-2.83, p < .001) use showed a higher association with frailty as compared to individuals who were non-users.

CONCLUSIONS

The use of benzodiazepine was cross-sectionally associated with frailty in older Veterans. These results suggest that screening for frailty in patients with past or current exposure to benzodiazepine medications may be necessary for proper management.

Pneumonia Risk Associated with the Use of Individual Benzodiazepines and Benzodiazepine Related Drugs among the Elderly with Parkinson's Disease

Most patients with Parkinson's disease (PD) gradually develop oropharyngeal dysphagia which is often associated with pneumonia risk. The possible association of benzodiazepine (BZD) and benzodiazepine related drugs (BZRD) use with pneumonia risk has received increasing attention but remains controversial. We investigated pneumonia risk associated with the use of BZDs and BZRDs in older adult patients with PD. This case-control study analyzed data of 551,975 older adult patients with PD between 2001 and 2018 in Taiwan. To minimize potential confounding, we used 1:4 propensity score matching to include older adult patients without pneumonia as controls. Incident pneumonia risk was significantly higher in current (adjusted odds ratio (aOR) = 1.25, 95% CI = 1.23-1.27) and past (aOR = 1.13, 95% CI = 1.11-1.15) users of BZDs. Regarding BZRDs, recent (aOR = 1.08, 95% CI = 1.06-1.11) and past (aOR = 0.89, 95% CI = 0.88-0.91) users had higher and lower risks of incident pneumonia, respectively. Pneumonia risk varied based on their use of BZDs and BZRDs. In these individuals, incident pneumonia risk was high in users of BZDs, such as midazolam, lorazepam, flunitrazepam, estazolam, and clonazepam. Regarding the use of BZRDs, zopiclone increased incident pneumonia risk.

Serum DBI and biomarkers of neuroinflammation in Alzheimer's disease and delirium

Background

Alzheimer’s disease (AD) patients often express significant behavioral symptoms: for this reason, accessible related biomarkers could be very useful. Neuroinflammation is a key pathogenic process in both AD and delirium (DEL), a clinical condition with behavioral symptoms resembling those of AD.

Methods

A total of n = 30 AD patients were recruited together with n = 30 DEL patients and n = 15 healthy controls (CTRL). Serum diazepam binding inhibitor (DBI), IL-17, IL-6, and TNF-α were assessed by ELISA.

Results

DBI serum levels were increased in AD patients with respect to CTRL (+ 81%), while DEL values were 70% higher than AD. IL-17 was increased in DEL with respect to CTRL (+ 146%), while AD showed dispersed values and failed to reach significant differences. On the other hand, IL-6 showed a more robust increase in DEL with respect to the other two groups (+ 185% and + 205% vs. CTRL and AD, respectively), and TNF-α failed to show any change.

Conclusions

DBI may be a very promising candidate for AD, perhaps marking psychomotor DEL-like symptoms, in view of developing future helping tool for practicing physicians. Furthermore, DBI rise in DEL offers novel cues for a better comprehension of the pathogenesis of this potentially fatal condition.

Is the risk of low birth weight or preterm labor greater when maternal stress is experienced during pregnancy? A systematic review and meta-analysis of cohort studies

Antenatal stress is linked to fetal risks that increase the chances of neonatal complications and reduction of child cognitive ability. Therefore, we aimed to evaluate if maternal stress affects fetal, neonatal or child development. The following databases were searched: MEDLINE (1966 to May 2016), Embase (1980 to May 2016), LILACS (1982 to May 2016) and CENTRAL (1972 to May 2016). Observational studies published in English and Portuguese were included whether there was any relationship between fetal and neonatal outcome, such as birth weight, preterm labor, child development with pregnant women that were subjected to any stress type during at least one month of follow-up. Two independent reviewers screened eligible articles, extracted data and assessed the risk of bias. Thus, 8 cohort studies with about 8,271 pregnant women and 1,081,151 children proved eligible. Results suggested a significant association between antenatal stress exposure and increasing rates of low birth weight (Odds ratio (OR) 1.68 [95% Confidential Interval (CI) 1.19, 2.38]). However, there was no statistically significance difference between non-exposed and exposed groups related to preterm labor (OR 1.98 [95% CI 0.91 to 4.31]; I2 = 68%, p = 0.04). Although, results were inconsistent with primary analysis suggesting a significant association between antenatal stress exposure and the occurrence of higher rates of preterm birth (OR 1.42 [95% CI 1.05 to 1.91]; I2 = 68%, p = 0.04) in the sensitivity analysis. Furthermore, the current review has suggested that stress perceived during antenatal negatively influences fetal life and child development. Yet, further studies are necessary with adequate sample size and longer follow-up time to confirm our findings.

Microglial recruitment of IL-1β-producing monocytes to brain endothelium causes stress-induced anxiety

Psychosocial stress contributes to the development of anxiety and depression. Recent clinical studies have reported increased inflammatory leukocytes in circulation of individuals with stress-related psychiatric disorders. Parallel to this, our work in mice shows that social stress causes release of inflammatory monocytes into circulation. In addition, social stress caused the development of prolonged anxiety that was dependent on inflammatory monocytes in the brain. Therefore, we hypothesize that chronic stress drives the production of inflammatory monocytes that are actively recruited to the brain by microglia, and these monocytes augment neuroinflammatory signaling and prolong anxiety. Here we show that repeated social defeat stress in mice activated threat appraisal centers in the brain that spatially coincided with microglial activation and endothelial facilitation of monocyte recruitment. Moreover, microglial depletion with a CSF1R antagonist prior to stress prevented the recruitment of monocytes to the brain and abrogated the development of anxiety. Cell-specific transcriptional profiling revealed that microglia selectively enhanced CCL2 expression, while monocytes expressed the pro-inflammatory cytokine interleukin-1β (IL-1β). Consistent with these profiles, the recruited inflammatory monocytes with stress adhered to IL-1R1⁺ neurovascular endothelial cells and this interaction was blocked by microglial depletion. Furthermore, disruption of IL-1β signaling by caspase-1^KO specifically within bone marrow-derived cells revealed that monocytes promoted anxiogenesis through stimulation of neurovascular IL-1R1 by IL-1β. Collectively, the development of anxiety during stress was caused by microglial recruitment of IL-1β-producing monocytes, which stimulated brain endothelial IL-1R1. Thus, monocyte IL-1β production represents a novel mechanism that underlies behavioral complications associated with stress-related psychiatric disorders.

Benzodiazepine and Z-drug use and risk of pneumonia in patients with chronic kidney disease: A population-based nested case-control study

BACKGROUND

Concerns were raised about pneumonia development from benzodiazepines (BZDs) and Z-drugs, but direct evidence is limited, conflicting and without examining the highly susceptible patients with chronic kidney disease (CKD) nor specifying the risk for different drug utilizations. This study aimed to investigate whether use of BZDs and Z-drugs was each associated with an increased risk of pneumonia in a CKD population.

METHODS

We performed a nested case-control study of 36,880 CKD patients analyzing the Taiwan National Health Insurance Database between 01/1/2000 and 12/31/2011. Among the study cohort, we identified 4,533 cases of pneumonia based on validated disease codes, chest x-ray examination, and prescriptions of respiratory antibiotics, and randomly selected 16,388 controls from risk sets, matched by sex, age, and number of CKD-related hospitalizations. All prescription filling records of BZDs and Z-drugs in the year before the event/index date were analyzed for cases and controls. Conditional logistic regressions were performed to estimate the odds ratios (ORs).

RESULTS

Current use of BZDs was associated with a 1.31-fold (95% CI, 1.18-1.26) increased risk of pneumonia compared to nonuse, but not for recent and past use. The risk from current BZD use was confined to new initiation (adjusted OR, 2.47; 95% CI, 2.02-3.03) or use for ≤ 30 days, and elevated to 2.88-fold (95% CI, 1.87-4.42) with parenteral administration. New initiation and current short-term use of Z-drugs was associated with a 2.94-fold (95% CI, 1.65-5.26) and 1.75-fold (95% CI, 1.13-2.72) increased risk of pneumonia, respectively. The findings were robust to adoption of a case-crossover study that analyzed cases only.

CONCLUSIONS

Use of BZRAs is associated with an increased risk of pneumonia in CKD patients, especially for patients newly initiating BZDs or Z-drugs or those injected with BZDs. Physicians should exercise cautions for signs of pneumonia when prescribing BZDs or Z-drugs to CKD patients.

Deficiency of prolyl oligopeptidase in mice disturbs synaptic plasticity and reduces anxiety-like behaviour, body weight, and brain volume

Prolyl oligopeptidase (PREP) has been implicated in neurodegeneration and neuroinflammation and has been considered a drug target to enhance memory in dementia. However, the true physiological role of PREP is not yet understood. In this paper, we report the phenotyping of a mouse line where the PREP gene has been knocked out. This work indicates that the lack of PREP in mice causes reduced anxiety but also hyperactivity. The cortical volumes of PREP knockout mice were smaller than those of wild type littermates. Additionally, we found increased expression of diazepam binding inhibitor protein in the cortex and of the somatostatin receptor-2 in the hippocampus of PREP knockout mice. Furthermore, immunohistochemistry and tail suspension test revealed lack of response of PREP knockout mice to lipopolysaccharide insult. Further analysis revealed significantly increased levels of polysialylated-neural cell adhesion molecule in PREP deficient mice. These findings might be explained as possible alteration in brain plasticity caused by PREP deficiency, which in turn affect behaviour and brain development.

GABAergic modulation with classical benzodiazepines prevent stress-induced neuro-immune dysregulation and behavioral alterations

OBJECTIVE

Psychosocial stress is associated with altered immunity, anxiety, and depression. Repeated social defeat (RSD), a model of social stress, triggers egress of inflammatory myeloid progenitor cells (MPCs; CD11b(+)/Ly6C(hi)) that traffic to the brain, promoting anxiety-like behavior. In parallel, RSD enhances neuroinflammatory signaling and long-lasting social avoidant behavior. Lorazepam and clonazepam are routinely prescribed anxiolytics that act by enhancing GABAergic activity in the brain. Besides binding to the central benzodiazepine binding site (CBBS) in the central nervous system (CNS), lorazepam binds to the translocator protein (TSPO) with high affinity causing immunomodulation. Clonazepam targets the CBBS and has low affinity for the TSPO. Here the aims were to determine if lorazepam and clonazepam would: (1) prevent stress-induced peripheral and central inflammatory responses, and (2) block anxiety and social avoidance behavior in mice subjected to RSD.

METHODS

C57/BL6 mice were divided into experimental groups, and treated with either lorazepam (0.10mg/kg), clonazepam (0.25mg/kg) or vehicle (0.9% NaCl). Behavioral data and tissues were collected the morning after the last cycle of RSD.

RESULTS

Lorazepam and clonazepam were effective in attenuating mRNA expression of CRH in the hypothalamus and corticosterone in plasma in mice subjected to RSD. Both drugs blocked stress-induced levels of IL-6 in plasma. Lorazepam and clonazepam had different effects on stress-induced enhancement of myelopoiesis and inhibited trafficking of monocytes and granulocytes in circulation. Furthermore, lorazepam, but not clonazepam, inhibited splenomegaly and the production of pro-inflammatory cytokines in the spleen following RSD. Additionally, lorazepam and clonazepam, blocked stress-induced accumulation of macrophages (CD11b(+)/CD45(high)) in the CNS. In a similar manner, both lorazepam and clonazepam prevented neuroinflammatory signaling and reversed anxiety-like and depressive-like behavior in mice exposed to RSD.

CONCLUSION

These data support the notion that lorazepam and clonazepam, aside from exerting anxiolytic and antidepressant effects, may have therapeutic potential as neuroimmunomodulators during psychosocial stress. The reversal of RSD-induced behavioral outcomes may be due to the enhancement of GABAergic neurotransmission, or some other off-target effect. The peripheral actions of lorazepam, but not clonazepam, seem to be mediated by TSPO activation.

Leukocyte Gene Expression in Patients with Medication Refractory Depression before and after Treatment with ECT or Isoflurane Anesthesia: A Pilot Study

Objective. To evaluate leukocyte gene expression for 9 selected genes (mRNAs) as biological markers in patients with medication refractory depression before and after treatment with ECT or isoflurane anesthesia (ISO). Methods. In a substudy of a nonrandomized open-label trial comparing effects of ECT to ISO therapy, blood samples were obtained before and after treatment from 22 patients with refractory depression, and leukocyte mRNA was assessed by quantitative PCR. Patients' mRNAs were also compared to 17 healthy controls. Results. Relative to controls, patients before treatment showed significantly higher IL10 and DBI and lower ADRA2A and ASIC3 mRNA (P < 0.025). Both ECT and ISO induced significant decreases after treatment in 4 genes: IL10, NR3C1, DRD4, and Sult1A1. After treatment, patients' DBI, ASIC3, and ADRA2A mRNA remained dysregulated. Conclusion. Significant differences from controls and/or significant changes after ECT or ISO treatment were observed for 7 of the 9 mRNAs studied. Decreased expression of 4 genes after effective treatment with either ECT or ISO suggests possible overlap of underlying mechanisms. Three genes showing dysregulation before and after treatment may be trait-like biomarkers of medication refractory depression. Gene expression for these patients has the potential to facilitate diagnosis, clarify pathophysiology, and identify potential biomarkers for treatment effects.

Reduced fasting plasma levels of diazepam-binding inhibitor in adolescents with anorexia nervosa

OBJECTIVE

Altered expression and/or function, both peripherally and centrally, of various neuropeptides is involved in the neurophysiology of anorexia nervosa (AN). Diazepam-binding inhibitor (DBI) is an interesting peptide for understanding this crosstalk. The aim of this work was to assess fasting plasma levels of DBI and leptin in patients with AN.

METHOD

Twenty-four AN adolescents were recruited together with 10 age-comparable healthy controls. Neuropeptide determinations were performed on plasma samples by enzyme-linked immunosorbent assays. Patients with AN were further characterized for the presence of a depressive state or anxiety by using, respectively, the Children's Depression Inventory or the State-Trait Anxiety Inventory form Y.

RESULTS

Levels of both plasma DBI and leptin were reduced in patients with AN (∼40 and ∼70%, respectively). DBI levels displayed a tendency to increase in the presence of a depressive state, although not with anxiety, whereas leptin levels correlated exclusively with body mass index.

DISCUSSION

These data further extend our knowledge of neuropeptide dysfunction in AN, and plasma DBI may represent a marker for this disease, in particular considering its correlation with comorbid mood disorders.

Neurosteroids, stress and depression: potential therapeutic opportunities

Neurosteroids are potent and effective neuromodulators that are synthesized from cholesterol in the brain. These agents and their synthetic derivatives influence the function of multiple signaling pathways including receptors for γ-aminobutyric acid (GABA) and glutamate, the major inhibitory and excitatory neurotransmitters in the central nervous system (CNS). Increasing evidence indicates that dysregulation of neurosteroid production plays a role in the pathophysiology of stress and stress-related psychiatric disorders, including mood and anxiety disorders. In this paper, we review the mechanisms of neurosteroid action in brain with an emphasis on those neurosteroids that potently modulate the function of GABA(A) receptors. We then discuss evidence indicating a role for GABA and neurosteroids in stress and depression, and focus on potential strategies that can be used to manipulate CNS neurosteroid synthesis and function for therapeutic purposes.

Systematic review of modulators of benzodiazepine receptors in irritable bowel syndrome: Is there hope?

Several drugs are used in the treatment of irritable bowel syndrome (IBS) but all have side effects and variable efficacy. Considering the role of the gut-brain axis, immune, neural, and endocrine pathways in the pathogenesis of IBS and possible beneficial effects of benzodiazepines (BZD) in this axis, the present systematic review focuses on the efficacy of BZD receptor modulators in human IBS. For the years 1966 to February 2011, all literature was searched for any articles on the use of BZD receptor modulators and IBS. After thorough evaluation and omission of duplicate data, 10 out of 69 articles were included. BZD receptor modulators can be helpful, especially in the diarrhea-dominant form of IBS, by affecting the inflammatory, neural, and psychologic pathways, however, controversies still exist. Recently, a new BZD receptor modulator, dextofisopam was synthesized and studied in human subjects, but the studies are limited to phase IIb clinical trials. None of the existing trials considered the neuroimmunomodulatory effect of BZDs in IBS, but bearing in mind the concentration-dependent effect of BZDs on cytokines and cell proliferation, future studies using pharmacodynamic and pharmacokinetic approaches are highly recommended.

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.

Diazepam leads to enhanced severity of orthopoxvirus infection and immune suppression

Benzodiazepines are drugs widely used as tranquilizers and in various other indications. We treated Balb/c mice with diazepam and infected them with cowpox (CPXV) and vaccinia virus (VACV). Disease index, weight loss and the antibody response were determined. Additionally the influence of different benzodiazepines on the mitogen response of human peripheral blood lymphocytes and spleen cells was tested. Diazepam led to earlier disease onset, prolonged duration of symptoms, higher weight loss and overall disease index in VACV infected mice. CPXV infected mice developed poxviral skin lesions only after drug administration and a significant decrease in the specific antibody response was also observed. Diazepam and alprazolam also inhibited the proliferative response of human lymphocytes/spleen cells in vitro but did not show noteworthy apoptotic effects. It is surprising that even a single dose of diazepam has a profound influence on the immune system, sufficient to facilitate symptomatic infectious disease. These data provide first evidence that commonly used drugs like Valium^® may augment severity of rare poxvirus infections such as CPXV or monkeypox. As VACV is still used as life vaccine against smallpox there is also a risk of enhanced side effects or possible interference with the success of vaccination.

Natural endogenous ligands for benzodiazepine receptors in hepatic encephalopathy

Benzodiazepines of natural origin (NBZDs) have been found in human blood and brains as well as in medicinal plants and foods. In plasma and brain tissue there are i.e. diazepam and nordiazepam equal to commercial drugs but there are also other benzodiazepine-like compounds termed "endozepines", which act as agonists at the benzodiazepine receptors of central type (CBR). A synthetic pathway for the production of NBZDs has not yet been found, but it has been suggested that micro-organisms may synthesize molecules with benzodiazepine-like structures. Hence NBZDs could be of both endogenous and exogenous source and be considered as natural anxyolitic and sedative. Interestingly there are also natural compounds, such as the polypeptide Diazepam Binding Inhibitor (DBI) acting as an "inversive agonist" implicated in fair and panic disorders. It has been suggested that NBZDs may play a role in the pathogenesis of hepatic encephalopathy (HE). Multidirectional studies evaluated NBZDs levels (1) in the blood of normal subjects, of cirrhotic with or without HE and in commercial benzodiazepine consumers; (2) in the blood of cirrhotic treated or not with a non-absorbable antibiotic; (3) in several constituents of our diet. In conclusion, NBZDs increase sometime in cirrhotics with or without HE but they reach concentrations not higher than those found in commercial benzodiazepines consumers. Hence NBZDs must be considered as occasional precipitating factor of HE and benzodiazepine antagonists only symptomatic drugs. The finding that NBZDs may be in part synthesized by intestinal bacterial flora and in part constituent of our diet underlines the importance to feed cirrhotic patients with selected food.

Association of a Met88Val diazepam binding inhibitor (DBI) gene polymorphism and anxiety disorders with panic attacks

Several lines of evidence suggest that anxiety disorders have a strong genetic component, but so far only few susceptibility genes have been identified. There is preclinical and clinical evidence for a dysregulation of the central gamma-aminobutyric acid (GABA)-ergic tone in the pathophysiology of anxiety disorders. Diazepam binding inhibitor (DBI) has been suggested to play a pivotal role in anxiety disorders through direct and indirect, i.e. via synthesis of neuroactive steroids, modulation of GABA(A) receptor function. These findings suggest that the DBI gene can be postulated as a candidate for a genetic association study in this disorder. Thus, single nucleotide polymorphisms (SNPs) of the DBI gene were investigated for putative disease associations in a German sample of anxiety disorder patients suffering from panic attacks and matched controls. We were able to detect a significant association between a non-synonymous coding variant of DBI with anxiety disorders with panic attacks. The rare allele of this polymorphism was more frequent in controls than in patients (OR=0.43; 95% CI: 0.19-0.95). In conclusion, these results suggest a central role of DBI genetic variants in the susceptibility for the development of anxiety disorders that are characterized by the occurrence of panic attacks.

Up-regulated l-type high voltage-gated calcium channels cause increase in diazepam binding inhibitor induced by sustained morphine exposure in mouse cerebrocortical neurons

Mechanisms of increase in diazepam binding inhibitor (DBI) mRNA expression in mouse cerebrocortical neurons after sustained morphine exposure were investigated. Increases in DBI and its mRNA expressions induced by sustained morphine (0.3 microM) exposure for 3 days were completely abolished by naloxone and nifedipine, but not by omega-agatoxin VIA and omega-conotoxin GIVA. Increase in [(3)H]diltiazem binding to the particulate fractions from the morphine-treated neurons was due to increased B(max) value with no changes in K(d) value. Western blot analysis on L-type high voltage-gated calcium channel (HVCC) subunits revealed the increased expressions of alpha1C, alpha1D, and alpha2/delta1 subunits and decreased of beta4 subunit expression, whereas expression of N- and P/Q-type HVCC subunits was not changed. These results indicate that morphine-induced increase in DBI mRNA expression is mediated via increased Ca(2+) entry through up-regulated L-type HVCCs.

A Functional Continuum of Regulatory Anxiety-Enhancing Peptides. The Search for Complexes Providing the Optimal Basis for Developing Inhibitory Therapeutic Agents

Regulatory peptides are actively involved in controlling most physiological processes. One such function is regulation of the level of anxiety and panic states. We report here a meta-analysis of data published from 1960 to 2004 on the effects of anxiety-enhancing regulatory peptides. The resulting database was used to investigate the organization and functioning of the anxiogenic regulatory peptide system. Using vector representation of the effects of these peptides, the spectra of physiological effects which might be provoked by each anxiety- and fear-increasing regulatory peptide alone and in combination were evaluated. Complexes of regulatory peptides with anxiogenic profiles with the greatest potential for the further experimental development of inhibitory pharmacological agents were identified.

Investigation of changes in global gene expression in the frontal cortex of early-weaned and socially isolated piglets using microarray and quantitative real-time RT-PCR

We hypothesize that early-weaned piglets experience aberrant expression of stress-responsive genes in the frontal cortex, a key brain area involved in cognitive function and behavior organization. To test this hypothesis, female early-weaned piglets (EW; n = 6) were weaned 10 days after birth, while non-weaned piglets (NW; n = 6) were left with their dams. Half of EW (n = 3) and NW (n = 3) animals were socially isolated (SI) for 15 min at 12 days of age, when all animals (n = 12) were euthanized and tissue collected. The effects of EW and SI were examined by gene expression profiling using cDNA microarray hybridizations, generated from a porcine brain cDNA library. A total of 103 genes were differentially expressed (P < 0.05, fold change >1.25) among four direct comparisons. Forty-two genes had known functions, from which 24 showed relevant brain-related functions. Quantitative real-time polymerase chain reaction (Q-RT-PCR) was used to confirm regulation of expression of a subset of 6 genes with important brain functions, selected from the microarray outcomes. In non-weaned animals, a significant suppression of mRNA abundance for carboxypeptidase E, 14-3-3 protein and phosphoprotein enriched in astrocytes 15 kDa was observed in response to SI. Also, in early-weaned animals, diazepam binding inhibitor and actin-related protein 2/3 complex mRNA levels were suppressed in response to SI. Results suggest that social isolation of non- and early-weaned piglets may impact expression of genes involved in regulation of neuronal function, development, and protection in the frontal cortex of young pigs.

Decreased density of peripheral benzodiazepine receptors in psychiatric patients after a suicide attempt

To date, two main types of benzodiazepine (BDZ) receptors have been identified: one of these is the so-called central receptor which is found mainly in the cortex, limbic areas and cerebellum, and the other is known as the peripheral receptor, which is found in the kidneys, lungs, ovaries, testes, adrenal glands and blood cells, but is present also in the central nervous system (CNS), in particular in glial cells. Although for some time the peripheral BDZ receptor has been considered an acceptor site with no pharmacological activity, recent data have suggested that it may be involved in a variety of actions, such as the response to stress. The presence of these receptors in blood platelets, which are considered a reliable, peripheral mirror of the same structures located in the SNC, prompted us to evaluate them in a group of psychiatric patients after a suicide attempt, as compared with healthy control subjects, by means of the specific binding of 3H-PK 11195. Suicide, with no doubt, may be considered one of the most stressful situations occurring to humans. The results showed the presence of a significant decrease in the density of 3H-PK 11195 binding sites in the patients, as compared with healthy control subjects. This finding may represent a non-specific indicator of a condition of stress, since peripheral BDZ receptors are modulated by stress and hormones, or it may result more from an abnormal metabolism of steroid substances which could play a pivotal role in the development of vulnerability towards suicide.

Changes in peripheral benzodiazepine receptors in patients with bipolar disorder

Peripheral benzodiazepine (BDZ) receptors were investigated by means of the binding of the specific ligand (3)H-PK 11195 to platelet membranes in patients suffering from bipolar disorder and in healthy controls. The results showed that the density (Bmax) of peripheral BDZ receptors was significantly higher in patients than in control subjects, with no change in the dissociation constant. No correlation with demographic or clinical features was observed. These findings would suggest that alterations of peripheral BDZ receptors are present in patients suffering from bipolar disorder, but it is premature to conclude whether they may be related to the pathophysiology of the disorder, or are secondary to changes occurring in other systems, such as those regulating the stress response.

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.

Stress sensitization of ethanol withdrawal-induced reduction in social interaction: inhibition by CRF-1 and benzodiazepine receptor antagonists and a 5-HT1A-receptor agonist

Repeated withdrawals from chronic ethanol sensitize the withdrawal-induced reduction in social interaction behaviors. This study determined whether stress might substitute for repeated withdrawals to facilitate withdrawal-induced anxiety-like behavior. When two 1-h periods of restraint stress were applied at 1-week intervals to rats fed control diet, social interaction was reduced upon withdrawal from a subsequent 5-day exposure to ethanol diet. Neither this ethanol exposure alone nor exposure to three restraint stresses alone altered this measure of anxiety. Further, the repeatedly stressed singly withdrawn rats continued to exhibit a reduction in social interaction 16 days later, upon withdrawal from re-exposure to 5 days of chronic ethanol, consistent with a persistent adaptation by the multiple-stress/withdrawal protocol. Weekly administration of corticosterone in place of stress induced no significant change in social interaction upon withdrawal from the single chronic ethanol exposure, indicative that corticoid release is not responsible for the stress-induced reduction in anxiety-like behavior during withdrawal. In the multiple-withdrawal protocol, stress applied during withdrawal from voluntary ethanol drinking by P-rats facilitated ethanol drinking sufficiently, to induce a withdrawal-induced reduction in social interaction. Administration of a CRF-1 receptor antagonist, a benzodiazepine receptor antagonist, or a 5-HT(1A) receptor agonist prior to each stress minimized sensitization of the withdrawal-induced reduction in anxiety-like behavior. Since these pharmacological consequences on the induction of anxiety-like behavior following the stress/withdrawal protocol are like those previously seen when these drug treatments were given prior to multiple withdrawals, evidence is provided that repeated stresses and multiple withdrawals sensitize the withdrawal reduction in social interaction by similar central adaptive mechanisms.

Psychological stress, but not physical stress, causes increase in diazepam binding inhibitor (DBI) mRNA expression in mouse brains

Effects of conditioned emotional stimuli (CES), which induce psychological stress, on the expression of cerebral diazepam binding inhibitor (DBI) mRNA in mouse were examined using a communication box. Cerebral DBI mRNA expression significantly increased in a time-dependent manner after the application of CES. The maximal enhancement of DBI mRNA expression was observed 2 days after the application of CES, and this increase faded out over 7 days after the treatment. Flunitrazepam (1 mg/kg), an agonist for central benzodiazepine (BZD) receptors, completely abolished the CES-induced elevation of cerebral DBI contents and its mRNA expressions. These results indicate that cerebral DBI is enhanced by psychological stress, which is regulated by central BZD receptors.

Functional continuum of regulatory peptides (RPs): vector model of RP-effects representation

During the past decades, bioactive (regulatory) peptides have been identified as the major players in the regulation of many important biological processes. Dozens of peptides have found their application as pharmaceutical agents, which further stimulated research in this field making it one of the most rapidly developing areas on the edge of biological science and medicine. However, the fast accumulation of enormous amounts of experimental data has revealed a great difficulty in their analysis and demanded the development of a systematic approach for generalization of the obtained information. We propose a new computer-based algorithm for studying biological activities of regulatory peptides and their groups based on their representation as vectors in n -dimensional functional space. Our method allows the rapid analysis of databases containing thousands of polyfunctional regulatory peptides with overlapping spectra of physiological activity. The described method permits to perform several types of correlations which, when applied to the large databases, could reveal new important information about the system of regulatory peptides. It can select the groups of peptides with similar physiological role (peptide constellations) and search for the optimal peptide combinations with predetermined spectrum of effects and minimal side effects for their further pharmacological application. It can also reveal the role of regulatory peptides in induction of chain physiological reactions.

Up-regulation of L-type voltage-dependent calcium channels after long term exposure to nicotine in cerebral cortical neurons

Effects of long term (72-h) exposure to low concentration (0.1 mum) of nicotine on various types of voltage-dependent Ca(2+) channels (VDCCs) and neuronal nicotinic acetylcholine receptors (nnAChRs) were examined using primary cultures of mouse cerebral cortical neurons. High potassium (30 mm KCl)-stimulated (45)Ca(2+) influx into the neurons increased with increasing the duration of nicotine exposure and its concentrations. The maximal increase of the KCl-stimulated (45)Ca(2+) influx was found 24 h after the initiation of exposure and thereafter maintained up to 72 h. This enhancement of KCl-induced (45)Ca(2+) influx after 72-h exposure to 0.1 mum nicotine was completely abolished by concomitant exposure with mecamylamine, an inhibitor for nnAChRs. Only the component of the KCl-induced (45)Ca(2+) influx observed after long term exposure to nicotine, which was sensitive to nifedipine, an inhibitor of L-type VDCCs, was facilitated, while the (45)Ca(2+) influx through P/Q- and N-type VDCCs showed no changes. Moreover, enhanced immunoreactivity against antibody for the alpha(1C) subunit of L-type VDCCs was recognized, whereas no changes in immunoreactivities against antibodies for alpha(1A) and alpha(1B) subunits of other types of VDCCs were noted. In addition, a Western blot analysis showed an increase of immunoreactivities against antibodies for alpha(1D) and alpha(2)/delta(1), and expression of mRNA for L-type VDCC subunit, alpha(1F), was also enhanced, although beta(4) mRNA expression was not changed. Whole cell patch clamp analysis revealed that the increase of the amplitude of Ba(2+) currents was also recognized in the neurons exposed to nicotine, and nicardipine reduced this increased amplitude to the level of the amplitude detected in nontreated neurons with nicardipine. The up-regulation of alpha(4) and beta(2) subunits, but not the alpha(3) subunit of nnAChRs, was also noted after the nicotine exposure when examining by the Western blot analysis. Taken together, these results indicate that the long term exposure of the neurons to a low concentration of nicotine induces both increased (45)Ca(2+) influx through up-regulated L-type VDCCs and nnAChR up-regulation.

[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.

Immunoreactive endozepine-like peptides in the brain and pituitary of the Atlantic hagfish, Myxine glutinosa

Endozepines are a family of peptides capable of displacing benzodiazepines from their specific binding sites, to which belong the diazepam-binding inhibitor and the octadecaneuropeptide (ODN). This paper reports the distribution of ODN-related peptides, investigated for the first time by immunocytochemistry, in different brain and pituitary regions of the Atlantic hagfish, Myxine glutinosa. Immunoreactive ODN-like material was found in the telencephalon at the level of bundles of different olfactory nerve fibres. Moreover, at the level of the pallium, immunoreactive multipolar neurons were observed in the pars parvocellularis of the stratum griseum superficialis. Similar immunopositive nerve cell bodies were found in the nucleus medialis of the central prosencephalic complex. In the mesencephalon, few immunoreactive neurons lining and contacting the mesencephalic ventricle were detected; such nerve cells could be involved in the regulation of cerebrospinal fluid homeostasis. Dorsally in the mesencephalon, numerous ODN-containing cell bodies were present in the area praetectalis. The rhomboencephalon was immunostained only in the octavolateral area and in the nucleus motorius magnocellularis of the trigeminal nerve. Furthermore, ODN immunoreactivity was also present in the nerve cells of ganglia of the ophthalmic division of the trigeminal nerve complex. The immunocytochemical patterns described here in the brain of M. glutinosa suggest an involvement of ODN-like peptides as neuromodulators in sensory pathways, such as olfactory and visual. Finally, ODN-like substances were localized in discrete populations of adenohypophysial cells and in tanycytes lining the neurohypophyseal walls, suggesting for endozepines a paracrine and/or endocrine control of pituitary hormones release and a neurohormone role respectively. These results could give new insights into the chemioarchitecture of the brain of myxinoids.

Benzodiazepines in perspective (II): The GABAA-Benzodiazepine Receptor Ligands

A huge number of natural and synthetic compounds modulate the function of the γ-aminobutyric acid type A receptor (GABAA-R) by interacting with several allosteric binding sites which may differ in the various GABAA-R subtypes. The benzodiazepine receptor (BDZ-R) is the most intensively studied allosteric site. It is the first allosteric modulatory site on a neurotransmitter receptor that has been found to mediate two opposite functions: facilitation and depression of GABAA-R function. The effects of BDZ-R ligands on behavior range from agonistic (anxiolytic, anticonvulsant, myore-laxant/ataxic and hypno-sedative effects) to inverse-agonistic (anxiety and panic, hypervigilance and convulsions). Of particular interest for the future are BDZ-R partial agonists, as they lack several of the undesired properties of classic full agonists. Furthermore the GABAA-R system shows a high plasticity. This polymorphism raises the possibility that ligands selective for distinct subtypes of BDZ-R may emerge as useful drugs. In both cases the possibility exists of achieving very subtle manipulations of GABAA-R function by using allosteric modulators.

Behavioral and hormonal effects of centrally injected "anxiogenic" neuropeptides in growing pigs

Records of behavior (alertness, posture, oro-nasal responses, activity level, and vocalization pattern) were made in prepubertal pigs (n = 6) during a 60-min period following central injections of equimolar (21 nmol) doses of porcine CRH (pCRH), urocortin (UCN), octadecaneuropeptide (ODN), or saline vehicle (SAL). Blood samples were also collected at 15-min intervals before, during, and after the test, and used to determine plasma cortisol, prolactin, and growth hormone concentrations. The pigs became excited and highly active after pCRH, and to a lesser extent following UCN administration, but were subdued when given ODN or SAL. None of the peptides significantly affected prolactin or growth hormone release, but both UCN, and especially pCRH, increased cortisol concentrations. The emotional responses induced by pCRH and UCN are consistent with observations in rodents, which indicate that centrally administered CRH-like peptides have anxiogenic effects. In contrast, ODN, which inhibits benzodiazepine binding at the GABA(A) receptor and is anxiogenic in rodents, lowered plasma cortisol and had no overt behavioral effects. Hence, at the dose administered, there was no evidence to indicate that ODN acted as an anxiogen in this species.

Benzodiazepine receptors and avian macrophage activity: diazepam decreases spreading and phagocytosis

The complex interrelations between the nervous system and the immune system have led to the creation of a new research area denoted neuroimmunology. The effects of stress on the immune response have long been observed in chickens. Since benzodiazepine receptors are involved in the stress reaction, we proposed to assess the importance of these receptors in the activity of chick peritoneal macrophages. We used 420 viable embryonated eggs of the commercial Hubbard broiler line treated through the chorioallantoid membrane on the 11th day of incubation: falsely manipulated (Sham group), with 40% propyleneglycol (PG) in simple Ringer solution (Vehicle group), and treated with diazepam (DZ), 8 mg/kg (DZ group). After hatching, the chicks were housed in metal rearing cages of the "battery" type for 5 weeks. At 36 days of age, 24 chicks from each treated group were divided at random into two groups of 12 animals each which were treated with DZ (2 mg/kg) or with 40% PPG in an equal volume once a day by the oral route for 4 days. Peritoneal macrophages were collected and submitted to the spreading an phagocytosis tests. Data were analyzed statistically using the SAS software (p < 0.05). Administration of DZ in ovo did not cause a significant decrease in egg hatchability, birth weight or performance parameters during the 5 weeks of assessment. However, the rate of macrophage spreading and phagocytosis was reduced. When administered at 40 days of age, DZ did not change the spreading rate but reduced the phagocytosis rate. There was no interaction between treatments. These results indicate that benzodiazepine receptors seem to be important for macrophage activity also in birds, as previously observed in rodents and primates. Since benzodiazepine receptors are involved in the response to stress, it is possible that the effects of stress on avian immunity may be mediated in part by these receptors.

Benzodiazepine-induced chemotaxis is impaired in monocytes from patients with generalized anxiety disorder

Peripheral benzodiazepine receptors (PBR) modulate chemotaxis and cytokine production of monocytes and lymphocytes. Since PBR are decreased in animal models of stress and in patients with anxiety disorders, in the present study we analyze the ability of monocytes obtained from patients suffering from generalized anxiety to migrate towards chemoattracting benzodiazepines. In these patients, the benzodiazepine-induced chemotaxis is completely abolished, while the response to the control chemoattractant formyl-leu-met-phe is still maintained. The chemotaxis responses are not restored after pharmacological treatment of the pathology. The decreased chemotactic response could be linked to a decreased number of PBR receptors present on monocytes of generalized anxiety disorder patients.

Diazepam-treated female rats: flumazenil- and PK 11195-induced withdrawal in the hippocampus CA1

Six female rats had a loading dose of 180 mg of diazepam (DZ) contained in two Silastic capsules implanted in their backs. Thereafter, a single 90-mg capsule was implanted weekly for 4 weeks prior to weekly microinjections of 1 microl of flumazenil (6.25, 12.5, or 25 microg) and PK 11195 (3.125, 6.25, or 12.5 microg) or vehicle into the CA1. Three control rats had empty capsules implanted but received only the high dose of flumazenil after 5 weeks. The time of DZ exposure spanned 8 weeks. Mean steady-state plasma levels of DZ were 1.06 +/- 0.11, and the mean total (DZ + metabolites) was 2.46 microg/ml +/- 0.37. Flumazenil elicited a dose-related precipitated withdrawal score (PAS) in DZ-treated rats (but not in controls) characterized by dose-related increases in convulsive (twitches and jerks), motor and autonomic signs, dose-related increases in the percent of total power in the low frequency (1-4 Hz), and decreases in the high-frequency (18-26 Hz) bands of the EEG recorded from the dentate and the amygdala. PK 11195 produced a dose-related increase in the 4-12 Hz band of the EEG recorded from the CA1, whereas the PAS was mild and not dose-related. However, the 6.25 and 12.5-microg doses elicited a significant PAS that tended to increase with dose. These data indicate that chronic DZ produces dependence, and that in the CA1 it involves the participation of central and possibly peripheral benzodiazepine (BZ) receptors located within this structure.

The octadecaneuropeptide-induced response of corticotropin-releasing hormone messenger RNA levels is mediated by GABA(A) receptors and modulated by endogenous steroids

The involvement of endogenous benzodiazepine octadecaneuropeptide in the regulation of corticotropin-releasing hormone messenger RNA expression has been studied using in situ hybridization technique. Intracerebroventricular injection of octadecaneuropeptide (4 microg/kg) induced a 26% decrease in the corticotropin-releasing hormone messenger RNA expression in the hypothalamic paraventricular nucleus. Concomitant injection of octadecaneuropeptide and i.p. injection of the GABA(A) receptor agonist muscimol (4 mg/kg) potentiated the corticotropin-releasing hormone messenger RNA decrease ( - 34%). The depressing effect of octadecaneuropeptide on corticotropin-releasing hormone gene expression was totally reversed by pretreatment of the animals with the GABA(A) receptor antagonist picrotoxin (5 mg/kg; i.p.) or by pretreatment with the benzodiazepine receptor antagonist flumazenil (4 mg/kg; i.p.). To determine the reciprocal involvement of adrenal and sexual steroids in this regulation, animals are adrenalectomized and/or castrated. Adrenalectomy reversed the effect induced by octadecaneuropeptide, which increased corticotropin-releasing hormone messenger RNA expression (+21%), while castration did not modify the negative influence of octadecaneuropeptide. When rats were adrenalectomized and castrated, the adrenalectomy influence was predominant, since octadecaneuropeptide increased significantly the hybridization signal (+18%). The involvement of neurosteroids, especially reduced metabolites of progesterone was also investigated. The concomitant injection of octadecaneuropeptide and subcutaneous injection of the 5alpha-reductase inhibitor MK-906 (14 mg/kg) to adrenalectomized and castrated rats, reduced significantly by 60% the increase of corticotropin-releasing hormone messenger RNA expression induced by octadecaneuropeptide. These results indicate that in vivo the endogenous benzodiazepine octadecaneuropeptide, via an activation of the benzodiazepine sites of the GABA(A) receptor, negatively modulates corticotropin-releasing hormone neuronal activity and that this modulation can be negatively or positively influenced by central and peripheral steroids.

Continuous treatment with nicotine increases diazepam binding inhibitor (DBI) and its mRNA in the mouse brain

Effect of chronic treatment with nicotine on DBI and its mRNA in mouse cerebral cortex were examined. Continuous treatment of mice with nicotine significantly increased DBI content and its mRNA expression, which was completely abolished by simultaneous administration of mecamylamine (1 mg/kg, i.p.). These results indicate that chronic functional interaction between nicotine and nicotinic acetylcholine receptors has a critical role in increases in DBI content and its mRNA expression.

Functional involvement of benzodiazepine receptors in ethanol-induced increases of diazepam binding inhibitor (DBI) and its mRNA in the mouse brain

We have attempted to clarify the mechanisms for alcohol (EtOH)-induced elevation of diazepam binding inhibitor (DBI) mRNA and to investigate whether the increase in DBI mRNA is paralleled with that in DBI using EtOH-treated mice and primary cultured neurons. Both the DBI content and the expression of DBI mRNA were elevated in the cerebral cortex of EtOH-inhaled and -withdrawn mice. Simultaneous administration of flunitrazepam (FLN) and Ro15-1788 with EtOH vapor completely abolished the EtOH-induced elevation of DBI mRNA. In addition, the exposure of the neurons for 3 days significantly elevated the expression of DBI mRNA, which was completely inhibited by concomitant exposure of FLN, Ro15-4513 and Ro-15-1788 with EtOH, while muscimol and bicuculline showed no effects on the EtOH-induced increase of DBI mRNA expression. These results indicate that functional interaction between EtOH and benzodiazepine (BDZ) receptors is a critical role in the increased expression of DBI mRNA.

Diazepam binding inhibitor (DBI) in the plasma of pediatric and adult epileptic patients

The polypeptide diazepam binding inhibitor (DBI) displays epileptogenic activity by binding to benzodiazepine receptors. We analyzed DBI concentrations in the plasma of pediatric and adult epileptic patients, as a possible peripheral marker in epilepsy. DBI plasma concentrations are significantly higher (+ 62%, P < 0.001) in adult patients and slightly but significantly higher (+15%, P < 0.01) in pediatric patients, compared to age-related controls. Strikingly, plasma DBI is much higher (+81%, P < 0.001) in generalized epilepsy in adults and in drug-resistant pediatric and adult patients. Based on these findings, plasma DBI may be considered as a peripheral biological marker of epilepsy and, in association with lymphocyte benzodiazepine receptor density, of anticonvulsant drug responsiveness.

Peripheral-type benzodiazepine receptor ligands and serum steroid hormones

The peripheral-type benzodiazepine receptors (PBR) are involved in various cellular functions, including steroidogenesis. The impact of these receptor ligands has been demonstrated mainly in steroidogenic cells. The aim of the present study was to assess in intact female rats the effect of chronic (21 days) administration of the PBR ligands PK 11195 (15 mg/kg) and Ro 5-4864 (5 mg/kg), the mixed ligand diazepam (5 mg/kg), and the central benzodiazepine receptor ligand clonazepam (1 mg/kg) on PBR binding characteristics in steroidogenic (ovary and adrenal) and non-steroidogenic (uterus and kidney) organs, as well as on serum hormonal steroids (estradiol, progesterone, and corticosterone). Selective and mixed PBR ligands up-regulated PBR density in the two steroidogenic organs, while Ro 5-4864 also induced elevation of the receptor density in the non-steroidogenic organs. In contrast to Ro 5-4864, PK 11195 treatment down-regulated renal PBR. Clonazepam elevated adrenal PBR. On the serum hormonal level, Ro 5-4864 suppressed estradiol secretion. The other ligands did not affect hormonal steroid levels. It appears that in female rats, at least at these doses and dosing schedules, there is no correlation between the impact of chronic in vivo exposure to these agents on PBR density and ovarian and adrenal hormone levels.

Benzodiazepines, anxiety and immunity

Experimental and clinical studies suggest that the central and peripheral benzodiazepine (BDZ) receptors together with their ligands form the molecular basis of a novel regulatory network that contributes to the effects of anxiety on immune status. The peripheral-type receptors located on phagocytes and glial cells appear to play a key role in mediating the effects of endogenous and exogenous BDZs both on the defence mechanisms that protect the host against pathogens and on inflammatory reactions that take place within the periphery and the brain in response to injury. In addition, the central-type receptor, which forms part of the gamma-aminobutyric acidA receptor complex, may contribute to the regulation of T-cell function by modulating the activity of the hypothalamo-pituitary-adrenocortical axis or the sympathoadrenal system or both, which, in turn, exert a significant effect on immune function. Thus, anxiogenic BDZs in general suppress the immune response, whereas anxiolytic BDZs may protect the individual from stress-induced immunosuppression.

125I-iomazenil binding shows stress- and/or diazepam-induced reductions in mouse brain: supporting data for 123I-iomazenil SPECT study of anxiety disorders

Effects of repeated swim stress on the binding of 125I-iomazenil were examined in the brains of diazepam-treated and non-treated mice. The mice were orally administered diazepam or vehicle (0.5% ethylene glycol) and subjected to daily swim stress (at 20 degrees C for 10 min) for seven consecutive days. The distribution and the amount of 125I-iomazenil binding were analyzed autoradiographically after in vivo and in vitro binding experiments. Repeated swim stress decreased the in vivo binding in the hippocampus (p < 0.05) and cerebral cortex (p < 0.05) of vehicle-treated mice but caused no significant changes in diazepam-treated mice. Subchronic treatment with diazepam decreased the in vivo binding approximately 50% in all brain regions examined (p < 0.01). The in vitro experiment, however, revealed no significant changes except in the hippocampus, where a small but significant decrease in the binding was observed after subchronic treatment with diazepam (p < 0.01). The stress- or diazepam-induced reductions seem to represent alterations in the in vivo environment related to 125I-iomazenil binding. These results suggest that we can investigate the pathophysiology of stress and anxiety with 123I-iomazenil SPECT. Care must be taken concerning the effects of benzodiazepines.

Prevention of ACTH- and adrenalectomy-induced muricidal behavior: by benzodiazepinic ligands

We investigated the effect of treatment with central (neuronal and glial) benzodiazepine binding site-active molecules on ACTH- or adrenalectomy (ADX)-induced muricidal behavior in male Wistar rats. Pretreatment (IP) with either flumazenil or clonazepam prevented the subsequent induction of ADX-induced behavior, but only flumazenil protected against ACTH-induced behavior; posttreatment in both cases induced no significant modifications. Using 4'-chloro-diazepam or PK 11195, both pre- and posttreatment afforded protection, the effect lasting longer (> 1 week) than that induced by flumazenil or clonazepam (2 days). Pretreatment with the GABAA agonist, muscimol, also resulted in complete protection, whereas posttreatment had only a slight effect.

Does prenatal stress impair coping and regulation of hypothalamic-pituitary-adrenal axis?

Prenatally stressed (PS) human infants and experimental animals show attentional deficits, hyperanxiety and disturbed social behavior. Impaired coping in stressful situations in adult PS monkeys and rodents is associated with dysregulation of the HPA axis, characterized by decreased feedback inhibition of corticotropin-releasing hormone (CRH) and prolonged elevation of plasma glucocorticoids in response to stress. PS rats have higher levels of CRH in the amygdala, fewer hippocampal glucocorticoid receptors and less endogenous opioid and GABA/BDZ (benzodiazepine) inhibitory activity. The mechanisms by which maternal stress induce these long-lasting changes in the developing fetal neuroaxis remain to be elucidated. It is suggested that impaired coping in stressful situations and dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, result from the action of maternal hormones released during stress on the developing fetus. The similarities in coping behavior and dysregulation of the HPA axis in PS animals to those in humans with depression, suggest that gestational stress, at a critical time during fetal development, may increase the propensity to develop this condition.