The effects of a dual orexin receptor antagonist on fear extinction memory and sleep in mice: Implications for exposure therapy

Extinction of conditioned fear is considered a fundamental process in the recovery from posttraumatic stress disorder and anxiety disorders. Sleep, especially rapid-eye-movement (REM) sleep, has been implicated in promoting extinction memory. The orexin system contributes to the regulation of sleep and wakefulness and emotional behaviors. In rodents, administrations of an orexin receptor antagonist following fear extinction training enhanced consolidation of extinction memory. Although orexin antagonists increase sleep, including REM sleep, the possible contribution of sleep to the effects of orexin antagonists on extinction memory has not been examined. Therefore, this study examined the effects of suvorexant, a dual orexin receptor antagonist, on extinction memory and sleep and their associations in mice. C57BL/6 mice underwent sleep recording for 24 h before and after contextual fear conditioning with footshocks and extinction learning during the early light phase or early dark phase. Mice were systemically injected with either 25 mg/kg of suvorexant or vehicle immediately after the extinction session. We found that suvorexant neither altered sleep nor improved extinction memory recall compared with vehicle. The higher percentages of REM sleep during the post-extinction dark phase were associated with lower extinction memory recall and greater freezing responses to the fear context. Results also indicate that animals did not reach complete extinction of fear with the fear extinction training protocol used in this study. These findings suggest that promoting REM sleep may not enhance fear extinction memory when extinction of fear is incomplete.

Evaluation of suvorexant for trauma-related insomnia

STUDY OBJECTIVES

Effective pharmacological treatments for sleep disturbance related to trauma with and without co-occurring posttraumatic stress disorder (PTSD) are needed. There is debate regarding what effects on rapid eye movement sleep (REMS) would be beneficial. Suvorexant is the first dual orexin receptor antagonist (DORA) approved for the treatment of insomnia. In contrast to most psychotropic agents, DORAs can enhance REMS while reducing arousal. We evaluated 6 weeks of suvorexant treatment for trauma-related insomnia in a double-blind, placebo-controlled clinical trial with clinical and polysomnographic evaluation.

METHODS

Participants with insomnia that followed a traumatic event were recruited from the community. Representation of current, past-only, and never having met criteria for PTSD was similar and most participants had experienced trauma-related nightmares. Participants were randomly assigned to receive suvorexant or placebo, initially at 10 mg and increased to 20 mg after 1 week, if tolerated. Polysomnography was obtained for screening, at baseline, and at 2 weeks of treatment.

RESULTS

The thirty-seven evaluable participants had significant improvement of PTSD and insomnia symptoms, however, there were no significant interactions with treatment condition. Medication was well tolerated with only one dropout being related to side effects. Within the suvorexant group increased REM segment duration correlated with concurrent PTSD symptom reduction. Nightmares remitted in all of the participants who received suvorexant and all but one of those receiving placebo.

CONCLUSIONS

A robust placebo response undermined detecting a medication effect. Further evaluation of DORAs for trauma-related insomnia, as well as factors contributing to placebo-response, are warranted.

Blocking the orexin system following therapeutic exposure promoted between session habituation, but not PTSD symptom reduction

There is a need to identify strategies to increase the effectiveness of treatments for posttraumatic stress disorder (PTSD). Sleep is often disturbed in PTSD and has been implicated in learning processes that underlie recovery from PTSD, including extinction of conditioned fear. Our prior study suggested that diminished arousal during sleep may enhance benefits of therapeutic exposure for PTSD. The orexin system regulates arousal, and blocking the system diminishes arousal and promotes sleep. We, therefore, examined whether a dual orexin receptor antagonist, suvorexant, administered following evening exposure sessions, would enhance their therapeutic effectiveness for PTSD. In this randomized double-blind placebo-controlled trial, adults with PTSD completed four written narrative exposure (WNE) sessions, two of which took place in the evening, and two the next morning. Participants received either suvorexant or placebo after each evening WNE. We found that suvorexant increased N3 sleep and decreased N2 sleep and rapid-eye-movement latency measured by polysomnography. Between session habituation indexed by subjective distress ratings was greater with suvorexant, but there was no group difference in the reduction of PTSD severity from baseline to 1-week follow-up. No safety concerns emerged. The present findings provide preliminary support for enhancement of an effect of therapeutic exposure for PTSD by suvorexant. Further studies with larger samples are needed to translate the present findings into clinical applications, including studies to develop optimal suvorexant administration and exposure session schedules to achieve persistent benefits to sleep and possibly greater treatment augmentation.

736 Evaluation of suvorexant for trauma-related insomnia

Introduction

Finding medication treatment that improves sleep disturbances with posttraumatic stress disorder (PTSD) has challenged the field of psychopharmacology with debate regarding the desirable profile of effects on sleep physiology. Evidence for fragmentation of REM sleep during the earlier stages of PTSD drew our interest to the first marketed dual orexin antagonist, suvorexant, which has been suggested in some studies to enhance REM sleep. This property has also raised concerns regarding potential exacerbation of nightmares and REM sleep related parasomnias. Insomnia is a common sequela of trauma exposure and can occur with and without other PTSD symptoms. The objective of our study was to evaluate the tolerability and preliminary efficacy of suvorexant for trauma related insomnia in a double blind, placebo controlled trial.

Methods

64 met initial inclusion criteria and 42 participants had evaluable results. 65% were female, and 66% African-American, mean age was 35yrs.All participants were screened by the Duke Sleep Disorders Interview to met criteria for insomnia that began or was exacerbated following a DSM5 Criterion A trauma. Approximately a third of the study group met criteria for either current PTSD, past (remitted PTSD), or no PTSD, and 56% reported histories of traumatic nightmares hat generally had diminished from their initial severity.

Results

Medication intolerance was infrequent with one participant in the med group reporting mild sedation that precluded a dose increase to 20mg, and another, moderate sedation with feelings of derealization that led to discontinuation. There was no evidence for emerging nightmare symptoms or REM-related parasomnias. Overall there was significant improvement in sleep and PTSD symptoms in both the placebo and med group and a modest rise in REM sleep in the med group that did not differentiate statistically from placebo.

Conclusion

Our findings suggest that distressing trauma related insomnia can occur with and without PTSD and that suvorexant is well tolerated in this population. A larger and more symptomatic group is required to more definitively evaluate efficacy.

Support (if any)

supported by a grant from Merck (MISP 53678)

Modular cis-regulatory logic of yellow gene expression in silkmoth larvae

Colour patterns in butterflies and moths are crucial traits for adaptation. Previous investigations have highlighted genes responsible for pigmentation (ie yellow and ebony). However, the mechanisms by which these genes are regulated in lepidopteran insects remain poorly understood. To elucidate this, molecular studies involving dipterans have largely analysed the cis-regulatory regions of pigmentation genes and have revealed cis-regulatory modularity. Here, we used well-developed transgenic techniques in Bombyx mori and demonstrated that cis-regulatory modularity controls tissue-specific expression of the yellow gene. We first identified which body parts are regulated by the yellow gene via black pigmentation. We then isolated three discrete regulatory elements driving tissue-specific gene expression in three regions of B. mori larvae. Finally, we found that there is no apparent sequence conservation of cis-regulatory regions between B. mori and Drosophila melanogaster, and no expression driven by the regulatory regions of one species when introduced into the other species. Therefore, the trans-regulatory landscapes of the yellow gene differ significantly between the two taxa. The results of this study confirm that lepidopteran species use cis-regulatory modules to control gene expression related to pigmentation, and represent a powerful cadre of transgenic tools for studying evolutionary developmental mechanisms.

Genetic diversity and relationships among native Japanese horse breeds, the Japanese Thoroughbred and horses outside of Japan using genome-wide SNP data

Eight horse breeds-Hokkaido, Kiso, Misaki, Noma, Taishu, Tokara, Miyako and Yonaguni-are native to Japan. Although Japanese native breeds are believed to have originated from ancient Mongolian horses imported from the Korean Peninsula, the phylogenetic relationships among these breeds are not well elucidated. In the present study, we compared genetic diversity among 32 international horse breeds previously evaluated by the Equine Genetic Diversity Consortium, the eight Japanese native breeds and Japanese Thoroughbreds using genome-wide SNP genotype data. The proportion of polymorphic loci and expected heterozygosity showed that the native Japanese breeds, with the exception of the Hokkaido, have relatively low diversity compared to the other breeds sampled. Phylogenetic and cluster analyses demonstrated relationships among the breeds that largely reflect their geographic distribution in Japan. Based on these data, we suggest that Japanese horses originated from Mongolian horses migrating through the Korean Peninsula. The Japanese Thoroughbreds were distinct from the native breeds, and although they maintain similar overall diversity as Thoroughbreds from outside Japan, they also show evidence of uniqueness relative to the other Thoroughbred samples. This is the first study to place the eight native Japanese breeds and Japanese Thoroughbred in context with an international sample of diverse breeds.

Emotional response to perceived racism and nocturnal heart rate variability in young adult African Americans

BACKGROUND

Heightened autonomic nervous system (ANS) arousal is a well-established contributor to the effect of stress on adverse cardiovascular health outcomes which disproportionately affect African Americans. ANS arousal is normally attenuated during sleep and compromise of this shift is associated with multiple adverse cardiovascular outcomes. Parasympathetic nervous system (PNS) dominance during sleep can be altered by stress. Racism has been recognized to have many negative health consequences in African Americans. Perceived racism has been linked to ANS activity, however, we are not aware of prior research on racism and nocturnal ANS balance.

OBJECTIVE

To examine relationships between perceived racism and nocturnal ANS activity indexed by heart rate variability (HRV) in healthy African American men and women age 18-35.

METHODS

Fifty-four participants completed the Perceived Racism Scale and had 24-hour ambulatory electrocardiogram recordings in their homes. Power spectral analysis was used to derive normalized high frequency (nHF) to index PNS activity which was computed by 5-minute epochs during wake and sleep.

RESULTS

Endorsement of racism and negative emotional reactions during the past year were inversely related to nHF during time in bed. Multiple regression analysis indicated that negative emotional reactions were a significant predictor of nHF during the sleep period F(2,54) = 4.213, p = .020, R² = 0.135 (adjusted R² = 0.103). Relationships during wake were not statistically significant.

CONCLUSION

Findings suggest that perseverative thoughts triggered by negative emotional reactions to racism influencing nocturnal ANS activity may be a pathway by which perceived racism affects health. Support: 3UL1TR001409-02S1 and R01HL087995 to Dr. Mellman.

Neighborhood stress and autonomic nervous system activity during sleep

Study Objectives

Stressful neighborhood environments are known to adversely affect health and contribute to health disparities but underlying mechanisms are not well understood. Healthy sleep can provide a respite from sustained sympathetic nervous system (SNS) activity. Our objective was to evaluate relationships between neighborhood stress and nocturnal and daytime SNS and parasympathetic nervous system (PNS) activity.

Methods

Eighty-five urban-residing African Americans (56.5% female; mean age of 23.0) participated. Evaluation included surveys of neighborhood stress and sleep-related vigilance, and continuous electrocardiogram (ECG) and actigraphic recording in participants' homes from which heart rate variability (HRV) analysis for low frequency/high frequency (LF/HF) ratio and normalized high frequency (nHF), as indicators of SNS and PNS activity, respectively, and total sleep time (TST), and wake after sleep onset were derived.

Results

All significant relationships with HRV measures were from the sleep period. Neighborhood disorder correlated negatively with nHF (r = -.24, p = .035). There were also significant correlations of HRV indices with sleep duration and sleep fears. Among females, LF/HF correlated with exposure to violence, r = .39, p = .008, and nHF with census tract rates for violent crime (r = -.35, p = .035). In a stepwise regression, TST accounted for the variance contributed by violent crime to nHF in the female participants.

Conclusions

Further investigation of relationships between neighborhood environments and SNS/PNS balance during sleep and their consequences, and strategies for mitigating such effects would have implications for health disparities.

Gender and age interact to predict the development of posttraumatic stress disorder symptoms following a motor vehicle accident

OBJECTIVE

Women have a greater overall risk of developing posttraumatic stress disorder (PTSD) than men after exposure to trauma. In addition to gender, other sociodemographic factors have been identified as risk factors for PTSD; however, research has typically examined these factors separately. Age has been found to contribute to the development of psychiatric disorders, and both linear and curvilinear relationships have been reported between age and risk of developing PTSD. Recent research has suggested that this relationship may vary depending on gender.

METHOD

We performed a secondary analysis of data from a prospective study of 287 (164 men, 123 women) motor vehicle accident (MVA) patients (aged 18-81) who completed clinical interviews 6 weeks, 6 months, and/or 1 year after an MVA.

RESULTS

Overall, women developed more severe PTSD symptoms than men; however, gender differences were small in the young (18-24 years) and the old (55 and older) groups. In women, age was not associated with PTSD symptoms at 6 weeks and 6 months; however, age was curvilinearly associated with PTSD severity at 1-year post-MVA such that middle-aged women reported greater symptom severity than younger and older women. Prior trauma exposure and social support mediated this relationship. In men, PTSD severity was not associated with age, but was related to income and social support.

CONCLUSIONS

These findings highlight age-based subgroups of women at elevated risk for PTSD following a traumatic injury and suggest that psychosocial intervention with middle-aged women following trauma exposure may help reduce the risk of persistent PTSD symptoms. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Simultaneous measurement of patient dose and distribution of indoor scattered radiation during digital breast tomosynthesis

INTRODUCTION

Breast cancer incidence increases from the age of 30 years. As this age range coincides with that in which women usually pursue pregnancy, undergoing medical examinations for conditions such as breast cancer is a concern, especially when pregnancy is uncertain during the first eight weeks. Moreover, in this age range, breast often exhibits a high density, thus compromising diagnosis. For such density, digital breast tomosynthesis (DBT) provides a more accurate diagnosis than 2D mammography given its higher sensitivity and specificity. However, radiation exposure increases during DBT, and it should be determined.

METHODS

We determined the entrance surface dose, scattered radiation dose, and average glandular dose (AGD), which can be mutually compared following an international protocol. Using our proposed method, the distribution of scattered radiation can be easily and quickly obtained with a minor load to the equipment. Then, we can determine the indoor scattered radiation and surface dose on patients during DBT.

RESULTS

We obtained a maximum AGD of 2.32 mGy. The scattered radiation was distributed over both sides with maximum of approximately 40 μGy, whereas the maximum dose around the eye was approximately 10 μGy.

CONCLUSION

By measuring doses using the proposed method, a correct dose information can be provided for patients to mitigate their concerns about radiation exposure. Although the obtained doses were low, their proper management is still required. Overall, the results from this study can help to enhance dose management for patients and safety management regarding indoor radiation.

Impact of strain, sex, and estrous cycle on gamma butyrolactone-evoked absence seizures in rats

Childhood absence epilepsy (CAE) is the most common pediatric epilepsy syndrome and is characterized by typical absence seizures (AS). AS are non-convulsive epileptic seizures characterized by a sudden loss of awareness and bilaterally generalized synchronous 2.5-4 Hz spike and slow-wave discharges (SWD). Gamma butyrolactone (GBL) is an acute pharmacological model of AS and induces bilaterally synchronous SWDs and behavioral arrest. Despite the long use of this model, little is known about its strain and sex-dependent features. We compared the dose-response profile of GBL-evoked SWDs in three rat strains (Long Evans, Sprague-Dawley, and Wistar), and examined the modulatory effects of estrous cycle on SWDs in female Wistar rats. We evaluated the number of seizures, the cumulative time seizing, and the average seizure duration as a function of dose, strain, and sex/estrous phase. Long Evans rats displayed the greatest sensitivity to GBL, followed by Wistar rats, and then by Sprague-Dawley rats. GBL-evoked SWDs were modulated by estrous cycle in female rats, with the lowest sensitivity to GBL occurring during metestrus. Wistar rats showed the greatest variability as a function of dose, and the least variability within dose; these features make this strain desirable for interventional studies. Moreover, our finding that the SWD response to GBL differs as a function of estrous cycle underscores the importance of cycle monitoring in studies examining female animals using this model. Together, these strain and sex-dependent findings provide guidance for future studies.

Enhancement of ADP-Induced Platelet Aggregation by Exercise Test in Coronary Patients and Its Prevention by Pyridinolcarbamate

ADP-induced platelet aggregation in citrated platelet rich plasma (CPRP) was examined using a photoelectric system. To exclude a variation in intensities of platelet aggregation in repeated measurements and to compare intensities of different samples, the maximum deflection of the optical density of CPRP induced by adding ADP solution was divided by a deflection of the optical density of the platelet free plasma and its value, shown as a percentage, was defined as an intensity of ADP-induced platelet aggregation. In this method, the linearity was found in the dose response curve of the platelet aggregation induced by 10−6, 3 × 10−6 and 10−5 molar of ADP with statistical significance. These variation coefficients were less than 5% in the responses induced by the higher doses of ADP. Changes in the ADP-induced platelet aggregation after a Master’s two step test were examined in 13 patients with angina pectoris 3 h after oral administration of placebo or 1 g of pyridinolcarbamate. Under placebo pretreatment, an enhancement of platelet aggregation was observed 1 min after the exercise test with statistical significance (P < 0.01 ∼ 0.05). In the cases of the same subjects pretreated with pyridinolcarbamate, such change was not observed at any time. Using a parallel line assay, an inhibitory effect of pyridinolcarbamate against enhancement of ADP-induced platelet aggregation after the exercise was also recognized with statistical significance (P < 0.01). In the 10 healthy volunteers, there was no statistically significant enhancement of ADP-induced platelet aggregation using any concentration of ADP 1 to 10 min after the exercise test.

Nocturnal autonomic nervous system activity and morning proinflammatory cytokines in young adult African Americans

Compromised sleep and increased sympathetic nervous system (SNS) activity are implicated in the pathogenesis of, and disparities in, cardiovascular disease. Parasympathetic dominance during sleep may be important for cardiovascular health. Sleep and autonomic balance influence immune activity, which impacts atherogenesis. We evaluated relationships between autonomic balance during sleep and morning levels of the immune activating cytokines, C-reactive protein (CRP) and interleukin (IL)-6. Ninety-four (59 female) young adult African Americans without medical conditions and substance use disorders spent 2 consecutive nights in a clinical research unit for sleep recordings and blood drawing on awakening. Cardiac tracings from the second sleep recording were analysed for heart rate variability (HRV). Body mass index was the only non-HRV measure correlated with cytokine levels. Indicators of SNS activity for the presleep, and first non-rapid eye movement (REM) and REM sleep periods were correlated independently with morning IL-6 levels. Altered autonomic balance during sleep may be a modifiable factor that influences immune activation.

Public health and healthcare-associated risk of electric, warm-water bidet toilets

BACKGROUND

In recent years, installation of bidet toilets within hospitals in Japan has raised concerns regarding potential for cross-contamination by antimicrobial-resistant bacteria from patients who are hospitalized over an extended period.

AIM

To investigate the distribution of antimicrobial-resistant bacteria recovered from bidet toilets at a university-affiliated hospital in Japan.

METHODS

All 292 electric bidet toilets at a university hospital were sampled for contamination. Swabs for culture were used to sample water-jet nozzles and toilet seats.

FINDINGS

Of the 292 toilet seats sampled, warm-water nozzles of 254 (86.9%) were found to be contaminated by one or more of the following organisms: Staphylococcus aureus, Streptococcus spp., Enterococcus spp., Enterobacteriaceae and non-Enterobacteriaceae Gram-negative bacteria. S. aureus was recovered from one water-jet nozzle and nine toilet seats; of these, meticillin-resistant S. aureus was recovered from the water-jet nozzle and from one toilet seat. Both the water-jet nozzle and seat of the same toilet were contaminated with a CTX-M-9 group extended-spectrum β-lactamase-producing Escherichia coli. Of the Gram-negative isolates recovered from samples, the organism with the highest frequency of isolation was Stenotrophomonas maltophilia, which was recovered from 39 bidet toilets.

CONCLUSION

Warm-water nozzles of bidet toilets are contaminated with a wide range of bacteria, making them a potential vehicle for cross-infection. In the hospital setting, shared use of bidet toilets must consider the clinical background of patients. Based on these findings, these devices must be part of the risk management programme, and steps should be included for monitoring and disinfection.