Benzodiazepines, anxiety and immunity

Overview of positron emission tomography in functional imaging of the lungs for diffuse lung diseases

Positron emission tomography (PET) is a quantitative molecular imaging modality increasingly used to study pulmonary disease processes and drug effects on those processes. The wide range of drugs and other entities that can be radiolabeled to study molecularly targeted processes is a major strength of PET, thus providing a noninvasive approach for obtaining molecular phenotyping information. The use of PET to monitor disease progression and treatment outcomes in DLD has been limited in clinical practice, with most of such applications occurring in the context of research investigations under clinical trials. Given the high costs and failure rates for lung drug development efforts, molecular imaging lung biomarkers are needed not only to aid these efforts but also to improve clinical characterization of these diseases beyond canonical anatomic classifications based on computed tomography. The purpose of this review article is to provide an overview of PET applications in characterizing lung disease, focusing on novel tracers that are in clinical development for DLD molecular phenotyping, and briefly address considerations for accurately quantifying lung PET signals.

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.

Diazepam Impairs Innate and Adaptive Immune Responses and Ameliorates Experimental Autoimmune Encephalomyelitis

Currently there is increasing attention on the modulatory effects of benzodiazepines on the immune system. Here, we evaluate how Diazepam (DZ) affects both innate and adaptive immunity. We observed that treatment with DZ and Lipopolysaccharide (LPS) on macrophages or dendritic cells (DCs) induced a defective secretion of IL-12, TNF-α, IL-6 and a lesser expression of classical activation markers as NO production and CD40 in comparison with LPS condition. More importantly, mice pre-treated with DZ and then challenged to LPS induced-septic shock showed reduced death. The DZ treatment shifted the LPS-induced pro-inflammatory cytokine production of peritoneal cells (PCs) to an anti-inflammatory profile commanded by IL-10. In agreement with this, DZ treatment prevented LPS-induced DC ability to initiate allogeneic Th1 and Th17 responses in vitro when compared with LPS-matured DC. Since these inflammatory responses are the key in the development of the experimental autoimmune encephalomyelitis (EAE), we treated EAE mice preventively with DZ. Mice that received DZ showed amelioration of clinical signs and immunological parameters of the disease. Additionally, DZ reduced the release of IFN-γ and IL-17 by splenocytes from untreated sick mice in vitro. For this reason, we decided to treat diseased mice therapeutically with DZ when they reached the clinical score of 1. Most importantly, this treatment ameliorated clinical signs, reduced the MOG-specific inflammatory cytokine production and prevented axonal damage. Altogether, these results indicate that DZ is a potent immunomodulator capable of controlling undesired innate and adaptive immune responses, both at the beginning of these responses and also once they have started.

The Effects of Anesthetics and Perioperative Medications on Immune Function: A Narrative Review

Preclinical and clinical studies have sought to better understand the effect of anesthetic agents, both volatile and intravenous, and perioperative adjuvant medications on immune function. The immune system has evolved to incorporate both innate and adaptive components, which are delicately interwoven and essential for host defense from pathogens and malignancy. This review summarizes the complex and nuanced relationship that exists between each anesthetic agent or perioperative adjuvant medication studied and innate and adaptive immune function with resultant clinical implications. The most commonly used anesthetic agents were chosen for review including volatile agents (sevoflurane, isoflurane, desflurane, and halothane), intravenous agents (propofol, ketamine, etomidate, and dexmedetomidine), and perioperative adjuvant medications (benzodiazepines, opioids, nonsteroidal anti-inflammatory drugs [NSAIDs], and local anesthetic agents). Patients who undergo surgery experience varying combinations of the aforementioned anesthetic agents and adjuncts, depending on the type of surgery and their comorbidities. Each has unique effects on immunity, which may be more or less ideal depending on the clinical situation. Further study is needed to better understand the clinical effects of these relationships so that patient-specific strategies can be developed to improve surgical outcomes.

Antidepressants plus benzodiazepines in major depressive disorder: a clinical dilemma with no recent answers from research

Comorbid anxiety symptoms are common in depression, and adding benzodiazepines to antidepressant treatment may seem a rational clinical solution. They also have potential to reduce the initial anxiety that may be caused by early antidepressant treatment due to their inhibitory effect via GABA-A receptor binding. This month's Cochrane Corner review examines the evidence behind combination treatment versus antidepressants alone in major depressive disorder, both in terms of the clinical and neuroscientific context. The review provides evidence that in the first 4 weeks of treatment, additional medication with a benzodiazepine may lead to greater improvements than antidepressant alone in terms of ratings of severity, response rates and remission rates, but not for measures of anxiety.

A Comparison of Hematological, Immunological, and Stress Responses to Capture and Transport in Wild White Rhinoceros Bulls (Ceratotherium simum simum) Supplemented With Azaperone or Midazolam

Capture and transport are essential procedures for the management and conservation of southern white rhinoceroses (Ceratotherium simum simum), but are associated with stress-induced morbidity and mortality. To improve conservation efforts, it is crucial to understand the pathophysiology of rhinoceros stress responses and investigate drug combinations that could reduce these responses. In this study we measured rhinoceros stress responses to capture and transport by quantifying hematological and immunological changes together with adrenal hormone concentrations. We investigated whether the potent anxiolytic drug midazolam was able to mitigate these responses compared to azaperone, which is more commonly used during rhinoceros transport. Twenty three wild white rhinoceros bulls were transported for 6 h (280 km) within the Kruger National Park for reasons unrelated to this study. Rhinoceroses were immobilized with either etorphine-azaperone (group A, n = 11) or etorphine-midazolam (group M, n = 12) intramuscularly by darting from a helicopter. Azaperone (group A) or midazolam (group M) were re-administered intramuscularly every 2 h during transport. Serial blood samples were collected at capture (TC), the start of transport (T0) and after 6 h of transport (T6). Changes in hematological and immunological variables over time and between groups were compared using general mixed models. Increases in plasma epinephrine and serum cortisol concentrations indicated that rhinoceroses mounted a stress response to capture and transport. Packed cell volume decreased from TC to T6 indicating that stress hemoconcentration occurred at TC. Neutrophils progressively increased and lymphocytes and eosinophils progressively decreased from T0 to T6, resulting in an increase in neutrophil to lymphocyte ratio; a characteristic leukocyte response to circulating glucocorticoids. A reduction in serum iron concentrations may suggest the mounting of an acute phase response. Rhinoceroses experienced a decrease in unsaturated fatty acids and an increase in lipid peroxidation products at capture and toward the end of transport indicating oxidative stress. Midazolam, at the dose used in this study, was not able to mitigate adrenal responses to stress and appeared to directly influence leukocyte responses.

Insight into the Structural Features of TSPO: Implications for Drug Development

The translocator protein (TSPO), an 18-kDa transmembrane protein primarily found in the outer mitochondrial membrane, is evolutionarily conserved and widely distributed across species. In mammals, TSPO has been described as a key member of a multiprotein complex involved in many putative functions and, over the years, several classes of ligand have been developed to modulate these functions. In this review, we consider the currently available atomic structures of mouse and bacterial TSPO and propose a rationale for the development of new ligands for the protein. We provide a review of TSPO monomeric and oligomeric states and their conformational flexibility, together with ligand-binding site and interaction mechanisms. These data are expected to help considerably the development of high-affinity ligands for TSPO-based therapies or diagnostics.

The effects of long-term opioid treatment on the immune system in chronic non-cancer pain patients: A systematic review

BACKGROUND AND OBJECTIVE

Opioids have been increasingly prescribed for chronic non-cancer pain (CNCP). An association between long-term opioid treatment (L-TOT) of CNCP patients and suppression of both the innate and the adaptive immune system has been proposed. This systematic review aims at investigating the effects of L-TOT on the immune system in CNCP patients.

DATABASES AND DATA TREATMENT

A systematic search of MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials and the CINAHL for relevant articles was performed. Studies examining measures of both the innate and the adaptive immune system in adult CNCP patients in L-TOT (≥4 weeks of intake) were included. Outcomes and the level of evidence were analysed.

RESULTS

A total of 382 studies were identified; however, 376 were excluded (352 inappropriate methodology, 21 duplicates, three full-text could not be obtained) and one randomized controlled trial (RCT) and five cross-sectional studies were included and analysed. L-TOT compared with no treatment was associated with a lower percentage of natural killer (NK) cells, a lower absolute number of CD56^bright NK cells, a higher absolute number of IL-2-activated NK cells and a higher concentration of IL-1β as a response to toll-like receptor (TLR) agonists stimulation (Pam3CSK4, LPS, Imiquimod). No other significant differences were reported. Generalizability of the results was limited due to inconsistency of outcomes and an overall low quality of the studies.

CONCLUSIONS

L-TOT may alter the immune system in CNCP patients, but the level of evidence is still weak. More studies are needed to clarify the impact of L-TOT on immune system function.

SIGNIFICANCE

This systematic review found indication that long-term opioid treatment alters the immune system in chronic non-cancer pain patients. These alterations involved the NK cells and IL-1β production. However, the level of evidence is weak.

Immune Modulation in Pediatric Sepsis

The initial host immune response to sepsis in children is characterized by a proinflammatory surge that can be associated with fever, capillary leak, and organ dysfunction. There is, however, a concurrent anti-inflammatory response that results in hyporesponsiveness of innate and adaptive immune cells. When severe, this response is termed immunoparalysis and is known to be associated with prolonged organ dysfunction, increased risk for nosocomial infection, and death in septic adults and children. Sepsis-induced immune suppression can be defined in the laboratory by reduced whole blood ex vivo - stimulated cytokine production capacities, reduced expression of human leukocyte antigen (HLA)-DR on circulating monocytes, and reduced absolute cell counts. While anti-inflammatory therapies have largely been unsuccessful at improving outcomes from adult and pediatric sepsis, the use of immunostimulatory therapies such as granulocyte macrophage colony-stimulating factor (GM-CSF) in patients with sepsis-induced immunoparalysis shows promise. A greater understanding of the risk factors for immunoparalysis along with the development and execution of immunophenotype-specific clinical trials of strategies to optimize innate and adaptive immune function are needed to further improve outcomes in septic children.

Imaging Pulmonary Inflammation

Lung inflammatory diseases contribute significantly to the socioeconomic burden of disease. Yet very few new, effective therapies for respiratory disease have been approved for use. A major contributing factor is the lack of biomarkers that can accurately quantify the lung inflammatory burden and can be used to understand the contribution of lung inflammation to loss in lung function. Molecular imaging approaches can detect and quantify the recruitment and activation of specific immune cells in lung inflammation. We review the clinical techniques used to image lung inflammation, provide an overview of clinical and emerging PET techniques for quantifying lung inflammation, and discuss potential clinical applications.

The association of medication use with clearance or persistence of oral HPV infection

PURPOSE

Persistent oral human papillomavirus (HPV) infection increases risk for oropharyngeal carcinoma, and people living with HIV have higher rates of oral HPV infection and related cancers. Some prescription medications have immunomodulatory effects, but the impact of medication use on oral HPV natural history is unknown.

METHODS

Scope^® oral rinse-and-gargle samples were collected semi-annually from 1,666 participants and tested for 37 types of oral HPV DNA using PCR; 594 HPV-infected participants with 1,358 type-specific oral HPV infections were identified. Data were collected on recent (past 6 months) use of medications. The relationship between medication use and oral HPV clearance was evaluated using Wei-Lin-Weissfeld regression, adjusting for biologic sex, prevalent versus incident infection, age, HIV status and CD4+ T cell count.

RESULTS

Out of 11 medications examined, oral HPV clearance was significantly reduced in participants reporting recent use of antipsychotics (HR 0.75, 95% CI 0.57-0.99), anxiolytics/sedatives (HR 0.78, 95% CI 0.63-0.96) and antidepressants (HR 0.82, 95% CI 0.67-0.999). Among antipsychotics users, effect modification by HIV status was observed, with reduced clearance in HIV-infected (HR 0.67, 95% CI 0.49-0.91), but not HIV-uninfected participants (p-interaction = 0.009). After adjusted analysis, antipsychotic use remained significantly associated with reduced oral HPV clearance overall (aHR 0.75, 95% CI 0.57-0.99), and when restricted to only HIV-infected participants (aHR 0.66, 95% CI 0.48-0.90). After adjustment, anxiolytic/sedative use and antidepressant use were no longer significantly associated with reduced oral HPV clearance.

CONCLUSIONS

Some medications were associated with decreased oral HPV clearance, most notably antipsychotic medications. These medications are prescribed for conditions that may have immunomodulating effects, so characteristics of underlying illness may have partially contributed to reduced oral HPV clearance.

Use of Zolpidem and Risk of Acute Pyelonephritis in Women: A Population-Based Case-Control Study in Taiwan

The aim of this study was to assess a possible correlation between zolpidem use and acute pyelonephritis (APN) in women in Taiwan. Therefore, we performed a case-control study involving the Taiwan's National Health Insurance Research Database between 2000 and 2011. This study included 3151 female participants aged 20 to 84 years who experienced the first bout of APN (case group) and 6015 randomly selected female participants without APN (control group). Zolpidem use was defined as "current," "early," or "late," if the last remaining 1 tablet for zolpidem was detected within 7 days, between 8 and 14 days, or ≥15 days before the date of APN diagnosis, respectively. The multivariable unconditional logistic regression model was used to calculate the odds ratios (ORs) with 95% confidence intervals (CIs) to assess the correlation between zolpidem use and APN. After adjusting for confounders, the multivariable analysis yielded an adjusted APN OR of 2.2 for participants with current zolpidem use (95%CI 1.7-2.8) compared with participants who never used zolpidem. The adjusted ORs gradually decreased to 1.4 for participants with early zolpidem use (95%CI 0.8-2.5) and 1.1 for participants with late zolpidem use (95%CI 0.9-1.2), but without statistical significance. Only patients with current zolpidem use had a significantly increased relative risk of APN. Additional large confirmatory studies are needed to illustrate a causal relationship. Meanwhile, physicians and pharmacists should be more cautious about the risk of APN when prescribing and dispensing zolpidem in women.

Low dose X-irradiation mitigates diazepam induced depression in rat brain

Depression is considered as one of the most prevalent health ailments. Various anti-depressant drugs have been used to provide succour to this ailment, but with little success and rather have resulted in many side effects. On the other hand, low dose of ionizing radiations are reported to exhibit many beneficial effects on human body by stimulating various biological processes. The present study was conducted to investigate the beneficial effects of low doses of X-rays, if any, during diazepam induced depression in rats. Female Sprague Dawley rats were segregated into four different groups viz: Normal control, Diazepam treated, X-irradiated and Diazepam + X-irradiated. Depression model was created in rats by subjecting them to diazepam treatment at a dosage of 2 mg/kg b.wt./day for 3 weeks. The skulls of animals belonging to X-irradiated and Diazepam + X-irradiated rats were X-irradiated with a single fraction of 0.5 Gy, given twice a day for 3 days, thereby delivered dose of 3 Gy. Diazepam treated animals showed significant alterations in the neurobehavior and neuro-histoarchitecture, which were improved after X-irradiation. Further, diazepam exposure significantly decreased the levels of neurotransmitters and acetylcholinesterase activity, but increased the monoamine oxidase activity in brain. Interestingly, X-rays exposure to diazepam treated rats increased the levels of neurotransmitters, acetylcholinesterase activity and decreased the monoamine oxidase activity. Further, depressed rats also showed increased oxidative stress with altered antioxidant parameters, which were normalized on X-rays exposure. The present study, suggests that low dose of ionizing radiations, shall prove to be an effective intervention and a novel therapy in controlling depression and possibly other brain related disorders.

The development of mitochondrial membrane affinity chromatography columns for the study of mitochondrial transmembrane proteins

Mitochondrial membrane fragments from U-87 MG (U87MG) and HEK-293 cells were successfully immobilized onto immobilized artificial membrane (IAM) chromatographic support and surface of activated open tubular (OT) silica capillary, resulting in mitochondrial membrane affinity chromatography (MMAC) columns. Translocator protein (TSPO), located in mitochondrial outer membrane as well as sulfonylurea and mitochondrial permeability transition pore (mPTP) receptors, localized to the inner membrane, were characterized. Frontal displacement experiments with multiple concentrations of dipyridamole (DIPY) and PK-11195 were run on MMAC (U87MG) column, and the binding affinities (Kd) determined were 1.08±0.49 and 0.0086±0.0006μM, respectively, consistent with previously reported values. Furthermore, binding affinities (Ki) for DIPY binding site were determined for TSPO ligands, PK-11195, mesoporphyrin IX, protoporphyrin IX, and rotenone. In addition, the relative ranking of these TSPO ligands based on single displacement studies using DIPY as marker on MMAC (U87MG) was consistent with the obtained Ki values. The immobilization of mitochondrial membrane fragments was also confirmed by confocal microscopy.

Zolpidem Use Associated With Increased Risk of Pyogenic Liver Abscess: A Case-Control Study in Taiwan

The purpose of this study was to explore the association between zolpidem use and pyogenic liver abscess in Taiwan.This was a population-based case-control study using the database of the Taiwan National Health Insurance Program since 2000 to 2011. We identified 1325 patients aged 20 to 84 years with the first-attack of pyogenic liver abscess as the cases, and 5082 patients without pyogenic liver abscess matched with sex, age, comorbidities, and index year of hospitalization for pyogenic liver abscess as the controls. Patients whose last remaining 1 tablet for zolpidem was noted ≤7 days before the date of admission for pyogenic liver abscess were defined as current use of zolpidem. Patients whose last remaining 1 tablet for zolpidem was noted >7 days before the date of admission for pyogenic liver abscess were defined as late use of zolpidem. Patients who never received 1 prescription for zolpidem were defined as never use of zolpidem. A multivariable unconditional logistic regression model was used to measure the odds ratio (OR) and 95% confidence interval (CI) to explore the association between zolpidem use and pyogenic liver abscess.After adjustment for possible confounding variables, the adjusted OR of pyogenic liver abscess was 3.89 for patients with current use of zolpidem (95% CI 2.89, 5.23), when compared with those with never use of zolpidem. The adjusted OR decreased to 0.85 for those with late use of zolpidem (95% CI 0.70, 1.03), but without statistical significance.Current use of zolpidem is associated with the increased risk of pyogenic liver abscess. Physicians should take the risk of pyogenic liver abscess into account when prescribing zolpidem.

Translocator protein (18 kDa) as a pharmacological target in adipocytes to regulate glucose homeostasis

As a major regulator in obesity and its associated metabolic complications, the proper functioning of adipocytes is crucial for health maintenance, thus serving as an important target for the development of anti-obese and anti-diabetic therapies. There is increasing evidence that mitochondrial malfunction is a pivotal event in disturbing adipocyte cell homeostasis. Among major mitochondrial structure components, the high-affinity drug- and cholesterol-binding outer mitochondrial membrane translocator protein (18 kDa; TSPO) has shown importance across a broad spectrum of mitochondrial functions. Recent studies demonstrated the presence of TSPO in white adipocyte mitochondria of mice, and administration of TSPO drug ligands to obese mice reduced weight gain and lowered glucose level. Therefore, it is of great interest to assess whether TSPO in adipocytes could serve as a drug target to regulate adipocyte activities with potential influence on weight control and glucose metabolism. Two structurally distinct TSPO drug ligands, PK 11195 and FGIN-1-27, improved the intracellular dynamics of 3T3-L1 adipocytes, such as the production and release of adipokines, glucose uptake, and adipogenesis. TSPO knockdown in either differentiated adipocytes or preadipocytes impaired these functions. Findings from 3T3-L1 cells were related to human primary cells, where TSPO expression was tightly associated with the metabolic state of primary adipocytes and the differentiation of primary preadipocytes. These results suggest that TSPO expression is essential to safeguard healthy adipocyte functions, and that TSPO activation in adipocytes improves their metabolic status in regulating glucose homeostasis. Adipocyte TSPO may serve as a pharmacologic target for the treatment of obesity and diabetes.

Diazepam Inhibits Proliferation of Lymph Node Cells Isolated from Rats with Experimental Autoimmune Encephalomyelitis

OBJECTIVE

Experimental autoimmune encephalomyelitis (EAE) is an inflammatory demyelinating disease with similarities to human multiple sclerosis involving peripheral activation of autoreactive T cells which infiltrate the central nervous system and react to self antigens leading to damage. In previous studies, we have demonstrated that treatment with diazepam decreases the incidence and histological signs associated with the disease and diminishes immunological responses. The aim of the present work was to evaluate direct effects of diazepam on isolated T cells involved in immune responses during the development of EAE.

METHODS

Animals were sensitized with whole myelin to induce EAE and sacrificed during the acute phase of the disease. In mononuclear cells isolated from popliteal lymph nodes, cell viability, apoptosis induction, proliferation and cytokine production were evaluated.

RESULTS

Diazepam did not have a toxic or proapoptotic effect on the cells, at least up to the concentration of 25 μM, but proliferation, CD8+ T-cell activation and proinflammatory cytokine production were dose-dependently decreased.

CONCLUSIONS

Diazepam has a direct inhibitory effect on the proliferation and activation of T lymphocytes isolated from the main lymphoid organ involved in disease onset and this could be one of the mechanisms that contribute to the beneficial effect previously observed with diazepam in vivo during EAE development.

Treatment of Rhizobium radiobacter bacteremia in a critically ill trauma patient

OBJECTIVE

To report the first case of Rhizobium radiobacter bacteremia in a critically ill trauma patient.

CASE SUMMARY

A 36-year-old female trauma patient hospitalized at The Regional Medical Center at Memphis developed bacteremia due to Rhizobium radiobacter on hospital day 9. The central line catheter tip culture from the same hospital day was negative. No source for the R radiobacter bacteremia was identified. Empirical and definitive antibiotic therapy consisted of cefepime 2 g intravenously every 8 hours for at total of 8 days. On completion of antibiotics, the patient demonstrated clinical resolution by immediate defervescence and gradual normalization of her white blood cell count. She demonstrated microbiologic success of therapy with negative blood cultures on hospital days 22, 34, 45, and 61. She was discharged on hospital day 80.

DISCUSSION

Rhizobium species are common soil and plant pathogens that rarely cause infections in humans. Previous reports of Rhizobium infections have been in immunocompromised patients; generally those with cancer or HIV infection. Intravenous catheters have commonly been cited as the source of infection. The trauma patient in this case constitutes a unique presentation of R radiobacter bacteremia when compared with other case reports. Her indwelling catheter was not the source of her infection, and her only identifiable risk factor for R radiobacter infection was hospitalization. However, she did possess potential reasons for development of an infection with an unusual organism such as R radiobacter. Potential immune modulating therapies included blood transfusions, opioid analgesics, benzodiazepines, general anesthetics, and surgical procedures. Finally, trauma itself has been associated with some degree of immunosuppression. All these issues may have placed the patient in this case at risk of an opportunistic infection like R radiobacter.

CONCLUSION

Based on this case, R radiobacter may be considered a potential pathogen causing bacteremia in critically ill trauma patients.

Proinflammatory cytokine levels in patients with conversion disorder

OBJECTIVE

It was aimed to evaluate the relationship between proinflammatory cytokine levels and conversion disorder both commonly known as stress regulated.

METHOD

Baseline proinflammatory cytokine levels-[Tumour necrosis factor alpha (TNF-α), Interleukin-1 beta (IL-1β), Interleukin-6 (IL-6)]-were evaluated with enzyme-linked immunosorbent assay in 35 conversion disorder patients and 30 healthy controls. Possible changes in proinflammatory cytokine levels were evaluated again, after their acute phase in conversion disorder patients.

RESULTS

Statistically significant decreased serum TNF-α levels were obtained in acute phase of conversion disorder. Those levels increased after acute conversion phase. There were no statistically significant difference observed between groups in serum IL-1β and (IL-6) levels.

CONCLUSIONS

Stress associated with conversion disorder may suppress immune function in acute conversion phase and may have diagnostic and therapeutic value.

Angiotensin II AT1 receptor blocker candesartan prevents the fast up-regulation of cerebrocortical benzodiazepine-1 receptors induced by acute inflammatory and restraint stress

Centrally acting Angiotensin II AT(1) receptor blockers (ARBs) protect from stress-induced disorders and decrease anxiety in a model of inflammatory stress, the systemic injection of bacterial endotoxin lipopolysaccharide (LPS). In order to better understand the anxiolytic effect of ARBs, we treated rats with LPS (50 μg/kg) with or without 3 days of pretreatment with the ARB candesartan (1mg/kg/day), and studied cortical benzodiazepine (BZ) and corticotrophin-releasing factor (CRF) receptors. We compared the cortical BZ and CRF receptors expression pattern induced by LPS with that produced in restraint stress. Inflammation stress produced a generalized increase in cortical BZ(1) receptors and reduced mRNA expression of the GABA(A) receptor γ(2) subunit in cingulate cortex; changes were prevented by candesartan pretreatment. Moreover, restraint stress produced similar increases in cortical BZ(1) receptor binding, and candesartan prevented these changes. Treatment with candesartan alone increased cortical BZ(1) binding, and decreased γ(2) subunit mRNA expression in the cingulate cortex. Conversely, we did not find changes in CRF(1) receptor expression in any of the cortical areas studied, either after inflammation or restraint stress. Cortical CRF(2) receptor binding was undetectable, but CRF(2) mRNA expression was decreased by inflammation stress, a change prevented by candesartan. We conclude that stress promotes rapid and widespread changes in cortical BZ(1) receptor expression; and that the stress-induced BZ(1) receptor expression is under the control of AT(1) receptor activity. The results suggest that the anti-anxiety effect of ARBs may be associated with their capacity to regulate stress-induced alterations in cortical BZ(1) receptors.

1,4-Benzodiazepin-2-ones in medicinal chemistry

1,4-Benzodiazepin-2-ones have applications in many areas of medicinal chemistry that are not restricted to 'classical' CNS treatments such as sedatives, epilepsy and muscle relaxants. We will describe selected examples of 1,4-benzodiazepin-2-ones in other areas of medicinal chemistry including uses as G-protein-coupled receptor antagonists, enzyme inhibitors and anticancer agents. Examples from our group will mainly show the use of palladacycle complexes of 1,4-benzodiazepin-2-ones as anticancer agents.

Relationship of anxiety state with lymphocyte subsets and the effect of Chinese medical treatment on anxiety in patients with chronic hepatitis B

OBJECTIVE

To analyze the relationship of anxiety state with CD4(+) level and CD4(+)/CD8(+) ratio and to observe the effect of Chinese medicine (CM) treatment on anxiety in chronic hepatitis B (CHB) patients.

METHODS

The anxiety state of 120 CHB patients was evaluated based on Hamilton Anxiety Scale (HAMA) scoring. According to the scores, 63 patients with scores ≥14 were classified to anxiety and 57 patients with scores <14 to non-anxiety. The differences in CD4(+) cells and CD4(+)/CD8(+) ratio between patients with anxiety and non-anxiety were analyzed. Moreover, 63 patients with anxiety were randomized into two groups: 31 in the control group were treated with lamivudine (100 mg per day) alone and 32 in the observation group were given equal dosage lamivudine combined with CM treatment depending on syndrome differentiation, all for 12 weeks. The effects of treatment on anxiety state and T-lymphocyte subsets as well as its impact on some CHB-related indices were observed and compared.

RESULTS

The anxiety state of CHB patients was negatively correlated with CD4(+) and CD4(+)/CD8(+); the level of CD4(+) in patients with anxiety was significantly lower than that in non-anxiety patients (P<0.01 or P<0.05). After treatment, anxiety state in the observation group was significantly improved, with their HAMA scores significantly lowered (P<0.01), and the levels of CD4(+) and CD4(+)/CD8(+) were significantly higher than those in the control group (P<0.05 or P<0.01). Moreover, the alanine transaminase recovery rate and the HBV-DNA-negative conversion rate in the observation group were significantly higher than those in the control group, respectively (P<0.05).

CONCLUSIONS

The anxiety state of CHB patients was related to CD4(+) and CD4(+)/CD8(+) levels. CM treatment could improve the anxiety state and showed certain regulatory effect on the patients' immune system.

Effects of different doses and schedules of diazepam treatment on lymphocyte parameters in rats

Benzodiazepines (BZD) are widely used for the treatment of anxiety. They enhance GABA-ergic neurotransmission through the binding on specific BDZ recognition sites, within the GABA(A) receptor-ion channel complex. However, recent studies showed that BZD also act on peripheral benzodiazepine receptor sites (PBR) or translocator protein 18 kDa (TSPO). Evidence for a direct immunomodulatory action for BZD emerged from studies that demonstrated the presence of TSPO on immune/inflammatory cells. The present study was designed to analyze the effects of diazepam on rat lymphocyte parameters, specifically on phenotype, cell proliferation and cell death. The effects of both acute and long-term (21 days) diazepam (1 and 10 mg/kg/day) administrations were evaluated. Results showed that diazepam (1 mg/kg) treatment did not change the immune parameters analyzed. However, both diazepam (10 mg/kg) acute and long-term treatments decreased the number of apoptotic cells; they also increased the percentage of T cytotoxic cells; decreased the percentage of B cells and increased the corticosterone serum levels. The induction of functional tolerance was suggested for the highest dose of diazepam (10 mg/kg), but not for the smaller dose (1 mg/kg) used, at least for diazepam effects on corticosterone serum levels. Diazepam effects were discussed as being related to the number of TSPO sites present on immune cells and/or to the increased levels of serum corticosterone observed after the treatments used.

Pyrazolo[1,5-a]pyrimidine acetamides: 4-Phenyl alkyl ether derivatives as potent ligands for the 18 kDa translocator protein (TSPO)

Herein, we report the synthesis of four new phenyl alkyl ether derivatives (7, 9-11) of the pyrazolo[1,5-a]pyrimidine acetamide class, all of which showed high binding affinity and selectivity for the TSPO and, in the case of the propyl, propargyl, and butyl ether derivatives, the ability to increase pregnenolone biosynthesis by 80-175% over baseline in rat C6 glioma cells. While these compounds fit our in silico generated pharmacophore for TSPO binding the current model does not account for the observed functional activity.

Translocator protein (18 kDa) mediates the pro-growth effects of diazepam on Ehrlich tumor cells in vivo

The Translocator Protein (TSPO), previously known as the peripheral-type benzodiazepine receptor, is a ubiquitous drug- and cholesterol-binding protein that is up regulated in several types of cancer cells. TSPO drug ligands (e.g., diazepam) induce or inhibit tumor cell proliferation, depending on the dose and tissue origin. We have previously shown that TSPO is expressed in Ehrlich tumor cells and that diazepam increases proliferation of these cells in vitro. Here, we investigated the in vivo effects of diazepam on Ehrlich tumor growth and the role of TSPO in mediating this process. Oral administration of diazepam to mice (3.0mg/kg/day for 7 days) produced plasma and ascitic fluid drug concentrations of 83.83 and 54.12 nM, respectively. Diazepam increased Ehrlich tumor growth, likely due to its ability to increase tumor cell proliferation and Reactive Oxygen Species production. Radioligand binding assays and nucleotide sequencing revealed that Ehrlich tumor cell TSPO had the same pharmacological and biochemical properties as TSPO described in other tumor cells. The estimated K(d) for PK 11195 in Ehrlich tumor cells was 0.44 nM and 8.70 nM (low and high binding site, respectively). Structurally diverse TSPO drug ligands with exclusive affinity for TSPO (i.e., 4-chlordiazepam, Ro5-4864, and isoquinoline-carboxamide PK 11195) also increased Ehrlich tumor growth. However, clonazepam, a GABA(A)-specific ligand with no affinity for TSPO, failed to do so. Taken together, these data suggest that diazepam induces in vivo Ehrlich tumor growth in a TSPO-dependent manner.

Single-step high-yield radiosynthesis and evaluation of a sensitive 18F-labeled ligand for imaging brain peripheral benzodiazepine receptors with PET

Elevated levels of peripheral benzodiazepine receptors (PBR) are associated with activated microglia in their response to inflammation. Hence, PBR imaging in vivo is valuable for investigating brain inflammatory conditions. Sensitive, easily prepared, and readily available radioligands for imaging with positron emission tomography (PET) are desirable for this purpose. We describe a new 18F-labeled PBR radioligand, namely [18F]N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline ([18F]9). [18F]9 was produced easily through a single and highly efficient step, the reaction of [18F]fluoride ion with the corresponding bromo precursor, 8. Ligand 9 exhibited high affinity for PBR in vitro. PET showed that [18F]9 was avidly taken into monkey brain and gave a high ratio of PBR-specific to nonspecific binding. [18F]9 was devoid of defluorination in rat and monkey and gave predominantly polar radiometabolite(s). In rat, a low level radiometabolite of intermediate lipophilicity was identified as [18F]2-fluoro-N-(2-phenoxyphenyl)acetamide ([18F]11). [18F]9 is a promising radioligand for future imaging of PBR in living human brain.

DPA-714, a new translocator protein-specific ligand: synthesis, radiofluorination, and pharmacologic characterization

The translocator protein (18 kDa) (TSPO), formerly known as the peripheral benzodiazepine receptor, is dramatically upregulated under pathologic conditions. Activated microglia are the main cell type expressing the TSPO at sites of central nervous system pathology. Radioligands for the TSPO can therefore measure active disease in the brain. This article details the synthesis, radiofluorination, and pharmacologic evaluation of a new TSPO-specific pyrazolopyrimidine, DPA-714.

METHODS

The affinity of DPA-714 for the TSPO was measured in rat kidney membranes with (3)H-PK11195. The in vitro functional activity of DPA-714 was measured in a steroidogenic assay in which the ability of DPA-714 to increase pregnenolone synthesis was measured with rat C6 glioma cells. The radiofluorination of DPA-714 was achieved by nucleophilic (18)F-fluoride displacement of the tosylate precursor. (18)F-DPA-714 was assessed in rats harboring unilateral quinolinic acid (QA) lesions. In addition, pretreatment experiments were performed with PK11195 (5 mg/kg), DPA-714 (1 mg/kg), and DPA-713 (1 mg/kg). The in vivo binding and biodistribution of (18)F-DPA-714 were determined in a baboon with PET. Experiments involving presaturation with PK11195 (1.5 mg/kg) and displacement with DPA-714 (1 mg/kg) were conducted to evaluate the specificity of radioligand binding.

RESULTS

In vitro binding studies revealed that DPA-714 displayed a high affinity for the TSPO (dissociation constant, 7.0 nM). DPA-714 stimulated pregnenolone synthesis at levels 80% above the baseline. (18)F-DPA-714 was prepared at a 16% radiochemical yield and a specific activity of 270 GBq/mumol. In rats harboring unilateral QA lesions, an 8-fold-higher level of uptake of (18)F-DPA-714 was observed in the ipsilateral striatum than in the contralateral striatum. Uptake in the ipsilateral striatum was shown to be selective because it was inhibited to the level in the contralateral striatum in the presence of PK11195, nonlabeled DPA-714, or DPA-713. PET studies demonstrated rapid penetration and good retention of (18)F-DPA-714 in the baboon brain. Pretreatment with PK11195 effectively inhibited the uptake of (18)F-DPA-714 in the whole brain, indicating its selective binding to the TSPO. The injection of nonlabeled DPA-714 20 min after the injection of (18)F-DPA-714 resulted in radioligand washout, demonstrating the reversibility of (18)F-DPA-714 binding.

CONCLUSION

(18)F-DPA-714 is a specific radioligand for the TSPO, displaying promising in vivo properties and thus warranting further investigation.

Melatonin and vitamin C administration ameliorate diazepam-induced oxidative stress and cell proliferation in the liver of rats

OBJECTIVE

Oxidative stress is a likely molecular mechanism in long-term diazepam administration. The benefits of antioxidants (melatonin and vitamin C) against diazepam-induced cell proliferation, DNA synthesis and oxidative damage were investigated in this study.

MATERIALS & METHODS

Four equal-sized groups of male rats [control, diazepam (3 mg/kg), diazepam plus melatonin (5 mg/kg) and diazepam plus vitamin C (50 mg/kg)] were used. Levels of lipid peroxides (LPO), superoxide dismutase (SOD) activity and glutathione (GSH) concentration were measured in tissue homogenates. Cell proliferation and rate of DNA synthesis were detected by autoradiography.

RESULTS

Results documented increased labelling index, (3)H-thymidine incorporation (DNA synthesis), LPO plus decrease in GSH levels and SOD activity in livers of diazepam-administered rats versus those of controls. When melatonin and vitamin C were given to diazepam-administered rats, they almost attenuated the increase of labelling index, DNA synthesis and LPO, and restored the levels of GSH and SOD activity.

CONCLUSION

These results suggest long-term hazard in use of drugs such as diazepam; they may be toxic and damage terminates in complex liver damage. Furthermore, melatonin and vitamin C may be useful in combating free radical-induced liver injury resulting from hazard and/or repeated diazepam administration.

Pharmacology of the beta-carboline FG-7,142, a partial inverse agonist at the benzodiazepine allosteric site of the GABA A receptor: neurochemical, neurophysiological, and behavioral effects

Given the well-established role of benzodiazepines in treating anxiety disorders, beta-carbolines, spanning a spectrum from full agonists to full inverse agonists at the benzodiazepine allosteric site for the GABA(A) receptor, can provide valuable insight into the neural mechanisms underlying anxiety-related physiology and behavior. FG-7,142 is a partial inverse agonist at the benzodiazepine allosteric site with its highest affinity for the alpha1 subunit-containing GABA(A) receptor, although it is not selective. FG-7,142 also has its highest efficacy for modulation of GABA-induced chloride flux mediated at the alpha1 subunit-containing GABA(A) receptor. FG-7,142 activates a recognized anxiety-related neural network and interacts with serotonergic, dopaminergic, cholinergic, and noradrenergic modulatory systems within that network. FG-7,142 has been shown to induce anxiety-related behavioral and physiological responses in a variety of experimental paradigms across numerous mammalian and non-mammalian species, including humans. FG-7,142 has proconflict actions across anxiety-related behavioral paradigms, modulates attentional processes, and increases cardioacceleratory sympathetic reactivity and neuroendocrine reactivity. Both acute and chronic FG-7,142 treatment are proconvulsive, upregulate cortical adrenoreceptors, decrease subsequent actions of GABA and beta-carboline agonists, and increase the effectiveness of subsequent GABA(A) receptor antagonists and beta-carboline inverse agonists. FG-7,142, as a partial inverse agonist, can help to elucidate individual components of full agonism of benzodiazepine binding sites and may serve to identify the specific GABA(A) receptor subtypes involved in specific behavioral and physiological responses.

Plasma levels of tumor necrosis factor-alpha and interleukin-6 in obsessive compulsive disorder

Aim. Recent research implicated place of an immune mechanism in the pathophysiology of obsessive-compulsive disorder (OCD). Despite increasing evidence involvement of cytokine release in OCD, results of the studies are inconsistent. The aim of this study was to evaluate the plasma levels of the cytokines; tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in OCD patients. Methods. Plasma concentrations of TNF-α and IL-6 were measured in 31 drug-free outpatients with OCD, and 31-year age and sex-matched healthy controls. TNF-α and IL-6 concentrations in blood were determined by enzyme-linked immunosorbent assay (ELISA). Results. Both TNF-α and IL-6 levels showed statistically significant increases in OCD patients compared to controls (P < .000, P < .001, resp.). In addition, the age of onset was negatively correlated with TNF-α level (r = −.402, P = .025) and duration of illness was weakly correlated with IL-6 levels (r : .357; P : .048) in patients group. Conclusion. OCD patients showed increases in TNF-α and IL-6 levels compared to the healthy controls. This study provides evidence for alterations in the proinflamatory cytokines which suggest the involvement of the immune system in the pathophysiology of OCD.

Kinetic evaluation in nonhuman primates of two new PET ligands for peripheral benzodiazepine receptors in brain

Peripheral benzodiazepine receptors (PBRs) are upregulated on activated microglia and are, thereby, biomarkers of cellular inflammation in brain. We recently developed two PET ligands with an aryloxyanilide structure to image PBRs and now evaluate the kinetics of these radiotracers in monkey to determine whether they are suitable to explore in human. Baseline and receptor-blocking scans were performed with [(11)C]PBR01 and [(18)F]PBR06 in conjunction with serial measurements of the arterial plasma concentration of parent radiotracer separated from radiometabolite. We used brain and plasma data with compartmental modeling to calculate regional brain distribution volume, which is equal to the ratio at equilibrium of the concentration of radioligand in brain to that of plasma. The distribution volume of [(11)C]PBR01 was inaccurately estimated in the baseline scans, possibly because of the short half-life of (11)C or the presence of radiometabolite in brain. In contrast, the distribution volume of [(18)F]PBR06 was stably determined within 200 min of scanning, and nondisplaceable uptake was only approximately 10% of total brain uptake. [(18)F]PBR06 is promising for use in human because brain activity could be quantified with standard compartmental models and showed higher ratios ( approximately 10:1) of specific to nonspecific uptake. A critical factor for human use will be whether the tracer has adequately fast wash out from brain relative to the half-life of the radionuclide to obtain stable values of distribution volume.

Effects of peripheral-type benzodiazepine receptor ligands on Ehrlich tumor cell proliferation

Peripheral-type benzodiazepine receptors have been found throughout the body, and particularly, in high numbers, in neoplastic tissues such as the ovary, liver, colon, breast, prostate and brain cancer. Peripheral-type benzodiazepine receptor expression has been associated with tumor malignity, and its subcellular localization is important to define its function in tumor cells. We investigated the presence of peripheral-type benzodiazepine receptors in Ehrlich tumor cells, and the in vitro effects of peripheral-type benzodiazepine receptors ligands on tumor cell proliferation. Our results demonstrate the presence of peripheral-type benzodiazepine receptor in the nucleus of Ehrlich tumor cells (85.53+/-12.60%). They also show that diazepam and Ro5-4864 (peripheral-type benzodiazepine receptor agonists) but not clonazepam (a molecule with low affinity for the peripheral-type benzodiazepine receptor) decreased the percentage of tumor cells in G0-G1 phases and increased that of cells in S-G2-M phases. The effects of those agonists were prevented by PK11195 (a peripheral-type benzodiazepine receptor antagonist) that did not produce effects by itself. Altogether, these data suggest that the presence of peripheral-type benzodiazepine receptor within the nucleus of Ehrlich tumor cells is associated with tumor malignity and proliferation capacity.

Peripheral benzodiazepine receptors on platelets of fibromyalgic patients

OBJECTIVE

The aim of the present study was to analyze if alterations of peripheral-type benzodiazepine receptor (PBR) characteristics occurred in platelet membranes of patients affected by primary fibromyalgia (FM).

DESIGN AND METHODS

Platelets were obtained from 30 patients with FM. Evaluation of kinetic parameters of PBR was performed using [(3)H] PK11195 as specific radioligand compared with 16 healthy volunteers.

RESULTS

The results showed a significant increase of PBR binding sites value in platelet membranes from FM patients (B(max) was 5366+/-188 fmol/mg vs. controls, 4193+/-341 fmol/mg, mean+/-SEM) (**p<0.01) but not for affinity value (K(d) was 4.90+/-0.39 nM vs. controls, 4.74+/-0.39 nM, mean+/-SEM) (p>0.05). Symptom severity scores (pain and tiredness) were positively correlated with B(max).

CONCLUSIONS

Our results showed an up-regulation of PBR in platelets of FM patients, and this seems to be related to the severity of fibromyalgic symptoms.

A centrally acting, anxiolytic angiotensin II AT1 receptor antagonist prevents the isolation stress-induced decrease in cortical CRF1 receptor and benzodiazepine binding

Long-term pretreatment with an angiotensin II AT1 antagonist blocks angiotensin II effects in brain and peripheral organs and abolishes the sympathoadrenal and hypothalamic-pituitary-adrenal responses to isolation stress. We determined whether AT1 receptors were also important for the stress response of higher regulatory centers. We studied angiotensin II and corticotropin-releasing factor (CRF) receptors and benzodiazepine binding sites in brains of Wistar Hannover rats. Animals were pretreated for 13 days with vehicle or a central and peripheral AT1 antagonist (candesartan, 0.5 mg/kg/day) via osmotic minipumps followed by 24 h of isolation in metabolic cages, or kept grouped throughout the study (grouped controls). In another study, we determined the influence of a similar treatment with candesartan on performance in an elevated plus-maze. AT1 receptor blockade prevented the isolation-induced increase in brain AT1 receptors and decrease in AT2 binding in the locus coeruleus. AT1 receptor antagonism also prevented the increase in tyrosine hydroxylase mRNA in the locus coeruleus. Pretreatment with the AT1 receptor antagonist completely prevented the decrease in cortical CRF1 receptor and benzodiazepine binding produced by isolation stress. In addition, pretreatment with candesartan increased the time spent in and the number of entries to open arms of the elevated plus-maze, measure of decreased anxiety. Our results implicate a modulation of upstream neurotransmission processes regulating cortical CRF1 receptors and the GABA(A) complex as molecular mechanisms responsible for the anti-anxiety effect of centrally acting AT1 receptor antagonists. We propose that AT1 receptor antagonists can be considered as compounds with possible therapeutic anti-stress and anti-anxiety properties.

Diazepam effects on carrageenan-induced inflammatory paw edema in rats: Role of nitric oxide

High doses of diazepam (10.0-20.0 mg/kg) were shown to reduce the volume of acute inflammatory paw edema in rats as a response to carrageenan administration. This effect was attributed to an action of diazepam on the peripheral-type benzodiazepine receptor (PBR) present in the adrenal and/or immune/inflammatory cells. The present study was undertaken to analyze the involvement of nitric oxide (NO) on the effects of diazepam on carrageenan-induced paw edema in rats (CIPE) and to look for the presence of PBR and inducible/constitutive NO synthases (NOS) on slices taken from the inflamed paws of diazepam-treated rats. For that, an acute inhibition of NO biosynthesis was achieved using 50.0 mg/kg No mega-nitro-L-arginine (L-NAME), L-arginine (300.0 mg/kg), the true precursor of NO, and D-arginine (300.0 mg/kg), its false substrate, were also used. The following results were obtained: (1) diazepam (10.0 and 20.0 mg/kg) decreased CIPE values in a dose- and time-dependent way; (2) diazepam effects on CIPE were increased by L-NAME pretreatment; (3) treatment with L-arginine but not with D-arginine reverted at least in part the decrements of CIPE values observed after diazepam administration; (4) PBR were found in endothelial and inflammatory cells that migrated to the inflammatory site at the rat paw; (5) confocal microscopy showed the presence of both PBR and NOS in endothelial and inflammatory cells taken from inflamed paw tissues of rats treated with diazepam a finding not observed in tissues provided from rats treated with diazepam's control solution. These results suggest an important role for NO on the effects of diazepam on CIPE. Most probably, these effects reflect a direct action of diazepam on PBR present in the endothelium of the microvascular ambient and/or on immune/inflammatory cells. An action like that would lead, among other factors, to a decrease in NO, generated by NO synthase, and thus in the mechanisms responsible for CIPE.

Diazepam effects on Ehrlich tumor growth and macrophage activity in mice

Besides the central gabaergic receptors described for benzodiazepines, peripheral type binding sites (PBR) were also identified for these molecules in endocrine steroidogenic tissues, immune organs and cells, such as macrophages and lymphocytes. PBR activation was reported to decrease innate immunity and host defense. The present experiment was designed to analyze the effects of diazepam on Ehrlich tumor growth, and on macrophage activity of Ehrlich tumor bearing mice. Results showed that diazepam (3.0 mg/kg/day, for 7 days) increased the number of Ehrlich tumor cells and the volume of tumor-induced ascitic fluid. These effects were not observed after smaller doses of diazepam, suggesting a dose-dependant effect. Furthermore, our results show that 3.0 mg/kg of diazepam, administered daily, for 2 days, decreased (1) the number of peritoneal leukocytes retrieved after injection of the Ehrlich tumor, (2) the percents of macrophage spreading, and (3) the levels of macrophage NO production. Diazepam (3.0 mg/kg/day for 2 days) had no effect on macrophage phagocytosis or on H2O2 production. The present data is discussed based on a direct and/or indirect action of diazepam. Particularly, our findings might be due to a direct effect of diazepam on PBRs present on macrophages and tumor cells, or could still be mediated by PBR stimulation within the hypothalamus-pituitary-adrenal (HPA) axis.

Improved synthesis of the peripheral benzodiazepine receptor ligand [11C]DPA-713 using [11C]methyl triflate

Recently, the pyrazolopyrimidine, [11C] N,N-Diethyl-2-[2-(4-methoxyphenyl)-5,7-dimethylpyrazolo[1,5-a]pyrimidin-3-yl]acetamide (DPA-713) has been reported as a new promising marker for the study of peripheral benzodiazepine receptors with positron emission tomography. In the present study, DPA-713 has been labelled from the corresponding nor-analogue using [11C]methyl triflate (CH3OTf). Conditions for HPLC were also modified to include physiological saline (aq. 0.9% NaCl)/ethanol:60/40 as mobile phase making it suitable for injection. The total time of radiosynthesis, including HPLC purification, was 18-20 min. This reported synthesis of [11C]DPA-713, using [11C]CH3OTf, resulted in an improved radiochemical yield (30-38%) compared to [11C]methyl iodide (CH3I) (9) with a simpler purification method. This ultimately enhances the potential of [11C]DPA-713 for further pharmacological and clinical evaluation. These improvements make this radioligand more suitable for automated synthesis which is of benefit where multi-dose preparations and repeated syntheses of radioligand are required.