Intranasal post-cardiac arrest treatment with orexin-A facilitates arousal from coma and ameliorates neuroinflammation

Jingqianshu granules mitigates premenstrual depression by regulating orexin signaling

Introduction: Premenstrual dysphoric disorder (PMDD), a severe form of premenstrual syndrome (PMS), is a serious health disorder that affects patient moods. It is caused by cyclic psychological symptoms and its pathogenesis is still unclear. Abnormalities in the basolateral amygdala (BLA) orexin system, which are important causes of the development of depressive mood, have not been reported in PMDD, so exploring its intrinsic mechanisms is meaningful for enriching the pathomechanisms of PMDD. Methods: High performance liquid chromatography was used for the determination of the active ingredients of Jingqianshu granules. Developing a rat model of premenstrual depression using the forced swimming test (FST). The experiment consisted of two parts. In Part 1, the rats were divided into the control group, the model group, the model + Jingqianshu group, and the model + fluoxetine group. The FST, open field test, and elevated plus maze test, were used to assess the behavior of the rats as well as to evaluate the effect of drug intervention. Immunofluorescence and RT-qPCR were used to detect the expression of orexin and its receptors OX1R and OX2R genes and proteins. The expression of Toll-like receptor 4, nuclear factor kappa-B, tumor necrosis factor-α, interleukin 6, and interleukin-1β in the BLA brain region was detected by Western-Blot. In part 2, the rats were injected intracerebrally with orexin-A. Observe the behavioral activities of rats in the control group, model group, and model+orexin-A group. Immunofluorescence was used to detect microglia in the BLA area of rats, and the expression levels of the above inflammatory factors were detected by Western-Blot. Results: The five components of Jingqianshu granules are: paeoniflorin, erulic acid, liquiritin, hesperidin, and paeonol. During the estrous cycle, rats exhibited depressive-like behavior during the non-receptive phase of the behavioral test, which disappeared during the receptive phase. Immunofluorescence and RT-qPCR showed reduced gene and protein expression of orexin, OX1R, and OX2R in the BLA region of rats in the model group.WB showed elevated levels of inflammatory factors. All returned to control levels after drug treatment. In part 2, injection of orexin-A into the BLA brain region of model rats resulted in reduced immunoreactivity of microglia and decreased expression levels of inflammatory factors. Discussion: Jianqianshu granules can achieve the purpose of treating premenstrual depression by regulating orexin-mediated inflammatory factors, which provides a new idea for further research on the pathogenesis of PMDD. However, the current study is still preliminary and the pathogenesis of PMDD is complex. Therefore, more in-depth exploration is needed.

Neuroprotective Approaches for Brain Injury After Cardiac Arrest: Current Trends and Prospective Avenues

With the implementation of improved bystander cardiopulmonary resuscitation techniques and public-access defibrillation, survival after out-of-hospital cardiac arrest (OHCA) has increased significantly over the years. Nevertheless, OHCA survivors have residual anoxia/reperfusion brain damage and associated neurological impairment resulting in poor quality of life. Extracorporeal membrane oxygenation or targeted temperature management has proven effective in improving post-cardiac arrest (CA) neurological outcomes, yet considering the substantial healthcare costs and resources involved, there is an urgent need for alternative treatment strategies that are crucial to alleviate brain injury and promote recovery of neurological function after CA. In this review, we searched PubMed for the latest preclinical or clinical studies (2016-2023) utilizing gas-mediated, pharmacological, or stem cell-based neuroprotective approaches after CA. Preclinical studies utilizing various gases (nitric oxide, hydrogen, hydrogen sulfide, carbon monoxide, argon, and xenon), pharmacological agents targeting specific CA-related pathophysiology, and stem cells have shown promising results in rodent and porcine models of CA. Although inhaled gases and several pharmacological agents have entered clinical trials, most have failed to demonstrate therapeutic effects in CA patients. To date, stem cell therapies have not been reported in clinical trials for CA. A relatively small number of preclinical stem-cell studies with subtle therapeutic benefits and unelucidated mechanistic explanations warrant the need for further preclinical studies including the improvement of their therapeutic potential. The current state of the field is discussed and the exciting potential of stem-cell therapy to abate neurological dysfunction following CA is highlighted.

The potential role of the orexin system in premenstrual syndrome

Premenstrual syndrome (PMS) occurs recurrently during the luteal phase of a woman's menstrual cycle and disappears after menstruation ends. It is characterized by abnormal changes in both the body and mood, and in certain cases, severe disruptions in daily life and even suicidal tendencies. Current drugs for treating PMS, such as selective serotonin reuptake inhibitors, do not yield satisfactory results. Orexin, a neuropeptide produced in the lateral hypothalamus, is garnering attention in the treatment of neurological disorders and is believed to modulate the symptoms of PMS. This paper reviews the advancements in research on sleep disturbances, mood changes, and cognitive impairment caused by PMS, and suggests potential pathways for orexin to address these symptoms. Furthermore, it delves into the role of orexin in the molecular mechanisms underlying PMS. Orexin regulates steroid hormones, and the cyclic fluctuations of estrogen and progesterone play a crucial role in the pathogenesis of PMS. Additionally, orexin also modulates the gamma-aminobutyric acid (GABA) system and the inflammatory response involved in coordinating the mechanism of PMS. Unraveling the role of orexin in the pathogenesis of PMS will not only aid in understanding the etiology of PMS but also hold implications for orexin as a novel target for treating PMS.

Hyperacute autonomic and cortical function recovery following cardiac arrest resuscitation in a rodent model

OBJECTIVE

There is a complex interaction between nervous and cardiovascular systems, but sparse data exist on brain-heart electrophysiological responses to cardiac arrest resuscitation. Our aim was to investigate dynamic changes in autonomic and cortical function during hyperacute stage post-resuscitation.

METHODS

Ten rats were resuscitated from 7-min cardiac arrest, as indicators of autonomic response, heart rate (HR), and its variability (HRV) were measured. HR was monitored through continuous electrocardiography, while HRV was assessed via spectral analysis, whereby the ratio of low-/high-frequency (LF/HF) power indicates the balance between sympathetic/parasympathetic activities. Cortical response was evaluated by continuous electroencephalography and quantitative analysis. Parameters were quantified at 5-min intervals over the first-hour post-resuscitation. Neurological outcome was assessed by Neurological Deficit Score (NDS, range 0-80, higher = better outcomes) at 4-h post-resuscitation.

RESULTS

A significant increase in HR was noted over 15-30 min post-resuscitation (p < 0.01 vs.15-min, respectively) and correlated with higher NDS (rs = 0.56, p < 0.01). LF/HF ratio over 15-20 min was positively correlated with NDS (rs = 0.75, p < 0.05). Gamma band power surged over 15-30 min post-resuscitation (p < 0.05 vs. 0-15 min, respectively), and gamma band fraction during this period was associated with NDS (rs ≥0.70, p < 0.05, respectively). Significant correlations were identified between increased HR and gamma band power during 15-30 min (rs ≥0.83, p < 0.01, respectively) and between gamma band fraction and LF/HF ratio over 15-20 min post-resuscitation (rs = 0.85, p < 0.01).

INTERPRETATIONS

Hyperacute recovery of autonomic and cortical function is associated with favorable functional outcomes. While this observation needs further validation, it presents a translational opportunity for better autonomic and neurologic monitoring during early periods post-resuscitation to develop novel interventions.

Quantification of Cerebral Vascular Autoregulation Immediately Following Resuscitation from Cardiac Arrest

Cerebral vascular autoregulation is impaired following resuscitation from cardiac arrest (CA), and its quantification may allow assessing CA-induced brain injury. However, hyperemia occurring immediately post-resuscitation limits the application of most metrics that quantify autoregulation. Therefore, to characterize autoregulation during this critical period, we developed three novel metrics based on how the cerebrovascular resistance (CVR) covaries with changes in cerebral perfusion pressure (CPP): (i) θCVR, which quantifies the CVR vs CPP gradient, (ii) a CVR-based transfer function analysis, and (iii) CVRx, the correlation coefficient between CPP and CVR. We tested these metrics in a model of asphyxia induced CA and resuscitation using seven adult male Wistar rats. Mean arterial pressure (MAP) and cortical blood flow recorded for 30 min post-resuscitation via arterial cannulation and laser speckle contrast imaging, were used as surrogates of CPP and cerebral blood flow (CBF), while CVR was computed as the CPP/CBF ratio. Using our metrics, we found that the status of cerebral vascular autoregulation altered substantially during hyperemia, with changes spread throughout the 0-0.05 Hz frequency band. Our metrics push the boundary of how soon autoregulation can be assessed, and if validated against outcome markers, may help develop a reliable metric of brain injury post-resuscitation.

Orexin-A aggravates cognitive deficits in 3xTg-AD mice by exacerbating synaptic plasticity impairment and affecting amyloid β metabolism

Dementia is the main clinical feature of Alzheimer's disease (AD). Orexin has recently been linked to AD pathogenesis, and exogenous orexin-A (OXA) aggravates spatial memory impairment in APP/PS1 mice. However, the effects of OXA on other types of cognitive deficits, especially in 3xTg-AD mice exhibiting both plaque and tangle pathologies, have not been reported. Furthermore, the potential electrophysiological mechanism by which OXA affects cognitive deficits and the molecular mechanism by which OXA increases amyloid β (Aβ) levels are unknown. In the present study, the effects of OXA on cognitive functions, synaptic plasticity, Aβ levels, tau hyperphosphorylation, BACE1 and NEP expression, and circadian locomotor rhythm were evaluated. The results showed that OXA aggravated memory impairments and circadian rhythm disturbance, exacerbated hippocampal LTP depression, and increased Aβ and tau pathologies in 3xTg-AD mice by affecting BACE1 and NEP expression. These results indicated that OXA aggravates cognitive deficits and hippocampal synaptic plasticity impairment in 3xTg-AD mice by increasing Aβ production and decreasing Aβ clearance through disruption of the circadian rhythm and sleep-wake cycle.

Effects of bright light therapy on neuroinflammatory and neuroplasticity markers in a diurnal rodent model of Seasonal Affective Disorder

BACKGROUND

Bright light therapy (BLT) is widely used for treating Seasonal Affective Disorder (SAD). However, the neural mechanisms underlying the therapeutic effects of BLT remain largely unexplored. The present study used a diurnal rodent (Nile grass rats; Arvicanthis niloticus) to test the hypothesis that the therapeutic effects of BLT could be, in part, due to reduced neuroinflammation and/or enhanced neuroplasticity. Our previous research has demonstrated that compared to grass rats housed in a summer-like daytime bright light condition (1000 lux), those housed in a winter-like daytime dim light condition (50 lux) showed increased depression- and anxiety-like behaviours, as well as impaired sociosexual behaviours and spatial memory, similar to what is observed in patients suffering from SAD.

MATERIALS AND METHODS

In the present study, male and female grass rats were housed under the winter-like dim daytime light condition (lights on 600-1800 hr, 50 lux). The experimental groups received daily 1-h early morning BLT from 0600-0700 using full-spectrum light (10,000 lux), while the control groups received narrowband red light (λmax, 780 nm). Following 4 weeks of treatment, the expression of several neuroinflammatory or plasticity markers was examined in the medial prefrontal cortex (mPFC), basolateral amygdala (BLA), and the CA1 of the dorsal hippocampus.

RESULTS

For the neuroinflammatory markers, BLT reduced TNF-α in the BLA of females, and upregulated CD11b in the mPFC and IL6 in the BLA in males. For the neuroplasticity markers, BLT downregulated BDNF in the CA1 and TrkB in all three brain regions in females but upregulated BDNF in the BLA and CA1 in males.

CONCLUSIONS

These results indicate that the therapeutic effects of BLT on sleep, mood, and cognition may be attributed in part to mechanisms involving neuroinflammation and neuroplasticity in corticolimbic brain regions. Moreover, these effects appear to vary between sexes.

Early Thalamocortical Reperfusion Leads to Neurologic Recovery in a Rodent Cardiac Arrest Model

BACKGROUND

Cerebral blood flow (CBF) plays an important role in neurological recovery after cardiac arrest (CA) resuscitation. However, the variations of CBF recovery in distinct brain regions and its correlation with neurologic recovery after return of spontaneous circulation (ROSC) have not been characterized. This study aimed to investigate the characteristics of regional cerebral reperfusion following resuscitation in predicting neurological recovery.

METHODS

Twelve adult male Wistar rats were studied, ten resuscitated from 7-min asphyxial CA and two uninjured rats, which were designated as healthy controls (HCs). Dynamic changes in CBF in the cerebral cortex, hippocampus, thalamus, brainstem, and cerebellum were assessed by pseudocontinuous arterial spin labeling magnetic resonance imaging, starting at 60 min after ROSC to 156 min (or time to spontaneous arousal). Neurologic outcomes were evaluated by the neurologic deficit scale at 24 h post-ROSC in a blinded manner. Correlations between regional CBF (rCBF) and neurological recovery were undertaken.

RESULTS

All post-CA animals were found to be nonresponsive during the 60-156 min post ROSC, with reductions in rCBF by 24-42% compared with HC. Analyses of rCBF during the post-ROSC time window from 60 to 156 min showed the rCBF recovery of hippocampus and thalamus were positively associated with better neurological outcomes (rs = 0.82, p = 0.004 and rs = 0.73, p < 0.001, respectively). During 96 min before arousal, thalamic and cortical rCBF exhibited positive correlations with neurological recovery (rs = 0.80, p < 0.001 and rs = 0.65, p < 0.001, respectively); for predicting a favorable neurological outcome, the thalamic rCBF threshold was above 50.84 ml/100 g/min (34% of HC) (area under the curve of 0.96), whereas the cortical rCBF threshold was above 60.43 ml/100 g/min (38% of HC) (area under the curve of 0.88).

CONCLUSIONS

Early magnetic resonance imaging analyses showed early rCBF recovery in thalamus, hippocampus, and cortex post ROSC was positively correlated with neurological outcomes at 24 h. Our findings suggest new translational insights into the regional reperfusion and the time window that may be critical in neurological recovery and warrant further validation.

Systemic administration of dendrimer N-acetyl cysteine improves outcomes and survival following cardiac arrest

Cardiac arrest (CA), the sudden cessation of effective cardiac pumping function, is still a major clinical problem with a high rate of early and long-term mortality. Post-cardiac arrest syndrome (PCAS) may be related to an early systemic inflammatory response leading to exaggerated and sustained neuroinflammation. Therefore, early intervention with targeted drug delivery to attenuate neuroinflammation may greatly improve therapeutic outcomes. Using a clinically relevant asphyxia CA model, we demonstrate that a single (i.p.) dose of dendrimer-N-acetylcysteine conjugate (D-NAC), can target "activated" microglial cells following CA, leading to an improvement in post-CA survival rate compared to saline (86% vs. 45%). D-NAC treatment also significantly improved gross neurological score within 4 h of treatment (p < 0.05) and continued to show improvement at 48 h (p < 0.05). Specifically, there was a substantial impairment in motor responses after CA, which was subsequently improved with D-NAC treatment (p < 0.05). D-NAC also mitigated hippocampal cell density loss seen post-CA in the CA1 and CA3 subregions (p < 0.001). These results demonstrate that early therapeutic intervention even with a single D-NAC bolus results in a robust sustainable improvement in long-term survival, short-term motor deficits, and neurological recovery. Our current work lays the groundwork for a clinically relevant therapeutic approach to treating post-CA syndrome.

Orexin-A inhibits cerebral ischaemic inflammatory injury mediated by the nuclear factor-κB signalling pathway and alleviates stroke-induced immunodepression in mice

Cerebral ischaemia is accompanied by infectious complications due to immunosuppression, known as stroke-induced immunodepression (SIID). Orexin-A (OXA), a neuropeptide produced in the hypothalamus, has been reported to have neuroprotective properties after stroke and is known to modulate inflammatory processes in peripheral tissues. The aim of this study was to determine the effects of orexin-A (OXA) on cerebral ischaemic inflammatory injury and SIID following experimental stroke. Cerebral ischaemia was induced in C57/BL6 mice by middle cerebral artery occlusion (MCAO). A mouse model of pneumonia and poststroke pneumococcal pneumonia was established by intratracheal inoculation with S. pneumoniae in a normal mouse or MCAO mouse model on the third day. We found that OXA postconditioning inhibited cerebral ischaemic inflammatory injury. The mechanism involved downregulation of the NF-κB signalling pathway. In addition, OXA may serve as a potential treatment target for attenuating stroke-induced immunodepression in mice.

Intranasal insulin and orexins to treat age-related cognitive decline

The intranasal (IN) administration of neuropeptides, such as insulin and orexins, has been suggested as a treatment strategy for age-related cognitive decline (ARCD). Because dysfunctional neuropeptide signaling is an observed characteristic of ARCD, it has been suggested that IN delivery of insulin and/or orexins may restore endogenous peptide signaling and thereby preserve cognition. IN administration is particularly alluring as it is a relatively non-invasive method that directly targets peptides to the brain. Several laboratories have examined the behavioral effects of IN insulin in young, aged, and cognitively impaired rodents and humans. These studies demonstrated improved performance on various cognitive tasks following IN insulin administration. Fewer laboratories have assessed the effects of IN orexins; however, this peptide also holds promise as an effective treatment for ARCD through the activation of the cholinergic system and/or the reduction of neuroinflammation. Here, we provide a brief overview of the advantages of IN administration and the delivery pathway, then summarize the current literature on IN insulin and orexins. Additional preclinical studies will be useful to ultimately uncover the mechanisms underlying the pro-cognitive effects of IN insulin and orexins, whereas future clinical studies will aid in the determination of the most efficacious dose and dosing paradigm. Eventually, IN insulin and/or orexin administration may be a widely used treatment strategy in the clinic for ARCD.

Arousing Effects of Electroacupuncture on the "Shuigou Point" in Rats with Disorder of Consciousness after Traumatic Brain Injury

Orexin is an important neuropeptide that stimulates cortical activation and arousal and is involved in the regulation of wakefulness and arousal. Our previous meta-analysis showed that acupuncture fared well in the treatment of TBI-induced DOC in which “shuigou (DU 26)” was the most important and frequent point targeted. In the present study, we investigated whether electroacupuncture (EA) promotes TBI-induced unconsciousness wakefulness via orexin pathway. A TBI rat model was established using a control cortical impact (CCI) model. In the stimulated group, TBI rats received EA (15 Hz, 1.0 mA, 15 min). In the antagonist group, TBI rats were intraperitoneally injected with the orexin receptor 1 (OX1R) antagonist SB334867 and received EA. Unconsciousness time was observed in each group after TBI, and electrocorticography (ECoG) was applied to detect rats' EEG activity. Immunohistochemistry, enzyme-linked immunosorbent assay, and western blot were used to assess the levels of orexin-1(OX1) and OX1R expression in the mPFC. We show that duration of unconsciousness and the ratio of delta power in ECoG in the EA group were significantly reduced compared with those in the TBI group. EA could increase OX1 and OX1R expression in the mPFC and reduced the loss of orexin-producing neurons in LHA. However, all the efficacy of EA was blocked by the OX1R antagonist SB334867. Our findings suggest that EA promotes the recovery of consciousness of TBI-induced unconscious rats via upregulation of OX1and OX1R expression in mPFC.

Intranasal Orexin After Cardiac Arrest Leads to Increased Electroencephalographic Gamma Activity and Enhanced Neurologic Recovery in Rats

Objectives

Prolonged cardiac arrest is known to cause global ischemic brain injury and functional impairment. Upon resuscitation, electroencephalographic recordings of brain activity begin to resume and can potentially be used to monitor neurologic recovery. We have previously shown that intrathecal orexin shows promise as a restorative drug and arousal agent in rodents. Our goal is to determine the electrophysiology effects of orexin in a rodent model of asphyxial cardiac arrest, focusing on the electroencephalographic activity in the gamma and super-gamma bands (indicative of return of higher brain function).

Design

Experimental animal study.

Setting

University-based animal research laboratory.

Subjects

Adult male Wistar rats.

Interventions

In an established model of asphyxial cardiac arrest (n = 24), we treated half of Wistar rats with orexin administered intranasally by atomizer 30 minutes post return of spontaneous circulation in one of two dose levels (10 and 50 µM); the rest were treated with saline as control. Continuous electroencephalographic recording was obtained and quantitatively analyzed for the gamma fraction. Gamma and high-frequency super-gamma band measures were compared against clinical recovery according to Neuro-Deficit Score.

Measurements and Main Results

Compared with the control cohort, the high-dose orexin cohort showed significantly better Neuro-Deficit Score 4 hours after return of spontaneous circulation (55.17 vs 47.58; p < 0.02) and significantly higher mean gamma fraction (0.251 vs 0.177; p < 0.02) in cerebral regions surveyed by rostral electrodes for the first 170 minutes after administration of orexin.

Conclusions

Our findings support early and continuous monitoring of electroencephalography-based gamma activity as a marker of better functional recovery after intranasal administration of orexin as measured by Neuro-Deficit Score in an established animal model of asphyxial cardiac arrest.

Palmitic acid methyl ester inhibits cardiac arrest-induced neuroinflammation and mitochondrial dysfunction

We previously discovered that palmitic acid methyl ester (PAME) is a potent vasodilator released from the sympathetic ganglion with vasoactive properties. Post-treatment with PAME can enhance cortical cerebral blood flow and functional learning and memory, while inhibiting neuronal cell death in the CA1 region of the hippocampus under pathological conditions (i.e. cerebral ischemia). Since mechanisms underlying PAME-mediated neuroprotection remain unclear, we investigated the possible neuroprotective mechanisms of PAME after 6 min of asphyxial cardiac arrest (ACA, an animal model of global cerebral ischemia). Our results from capillary-based immunoassay (for the detection of proteins) and cytokine array suggest that PAME (0.02 mg/kg) can decrease neuroinflammatory markers, such as ionized calcium binding adaptor molecule 1 (Iba1, a specific marker for microglia/macrophage activation) and inflammatory cytokines after cardiopulmonary resuscitation. Additionally, the mitochondrial oxygen consumption rate (OCR) and respiratory function in the hippocampal slices were restored following ACA (via Seahorse XF24 Extracellular Flux Analyzer) suggesting that PAME can ameliorate mitochondrial dysfunction. Finally, hippocampal protein arginine methyltransferase 1 (PRMT1) and PRMT8 are enhanced in the presence of PAME to suggest a possible pathway of methylated fatty acids to modulate arginine-based enzymatic methylation. Altogether, our findings suggest that PAME can provide neuroprotection in the presence of ACA to alleviate neuroinflammation and ameliorate mitochondrial dysfunction.

Acute-stage MRI cerebral oxygen consumption biomarkers predict 24-hour neurological outcome in a rat cardiac arrest model

Brain injury following cardiac arrest (CA) is thought to be caused by a sudden loss of blood flow resulting in disruption in oxygen delivery, neural function and metabolism. However, temporal trajectories of the brain's physiology in the first few hours following CA have not been fully characterized. Furthermore, the extent to which these early measures can predict future neurological outcomes has not been determined. The present study sought to perform dynamic measurements of cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO₂ ) with MRI in the first 3 hours following the return of spontaneous circulation (ROSC) in a rat CA model. It was found that CBF, OEF and CMRO₂ all revealed a time-dependent increase during the first 3 hours after the ROSC. Furthermore, the temporal trajectories of CBF and CMRO₂ , but not OEF, were different across rats and related to neurologic outcomes at a later time (24 hours after the ROSC) (P < .001). Rats who manifested better outcomes revealed faster increases in CBF and CMRO₂ during the acute stage. When investigating physiological parameters measured at a single time point, CBF (ρ = 0.82, P = .004) and CMRO₂ (ρ = 0.80, P = .006) measured at ~ 3 hours post-ROSC were positively associated with neurologic outcome scores at 24 hours. These findings shed light on brain physiological changes following CA, and suggest that MRI measures of brain perfusion and metabolism may provide a potential biomarker to guide post-CA management.

Cortical Transcriptomic Alterations in Association With Appetitive Neuropeptides and Body Mass Index in Posttraumatic Stress Disorder

BACKGROUND

The molecular pathology underlying posttraumatic stress disorder (PTSD) remains unclear mainly due to a lack of human PTSD postmortem brain tissue. The orexigenic neuropeptides ghrelin, neuropeptide Y, and hypocretin were recently implicated in modulating negative affect. Drawing from the largest functional genomics study of human PTSD postmortem tissue, we investigated whether there were molecular changes of these and other appetitive molecules. Further, we explored the interaction between PTSD and body mass index (BMI) on gene expression.

METHODS

We analyzed previously reported transcriptomic data from 4 prefrontal cortex regions from 52 individuals with PTSD and 46 matched neurotypical controls. We employed gene co-expression network analysis across the transcriptomes of these regions to uncover PTSD-specific networks containing orexigenic genes. We utilized Ingenuity Pathway Analysis software for pathway annotation. We identified differentially expressed genes (DEGs) among individuals with and without PTSD, stratified by sex and BMI.

RESULTS

Three PTSD-associated networks (P < .01) contained genes in signaling families of appetitive molecules: 2 in females and 1 in all subjects. We uncovered DEGs (P < .05) between PTSD and control subjects stratified by sex and BMI with especially robust changes in males with PTSD with elevated vs normal BMI. Further, we identified putative upstream regulators (P < .05) driving these changes, many of which were enriched for involvement in inflammation.

CONCLUSIONS

PTSD-associated cortical transcriptomic modules contain transcripts of appetitive genes, and BMI further interacts with PTSD to impact expression. DEGs and inferred upstream regulators of these modules could represent targets for future pharmacotherapies for obesity in PTSD.

Neurophysiology and Treatment of Disorders of Consciousness Induced by Traumatic Brain Injury: Orexin Signaling as a Potential Therapeutic Target

BACKGROUND

Traumatic brain injury (TBI) can cause disorders of consciousness (DOC) by impairing the neuronal circuits of the ascending reticular activating system (ARAS) structures, including the hypothalamus, which are responsible for the maintenance of the wakefulness and awareness. However, the effectiveness of drugs targeting ARAS activation is still inadequate, and novel therapeutic modalities are urgently needed.

METHODS

The goal of this work is to describe the neural loops of wakefulness, and explain how these elements participate in DOC, with emphasis on the identification of potential new therapeutic options for DOC induced by TBI.

RESULTS

Hypothalamus has been identified as a sleep/wake center, and its anterior and posterior regions have diverse roles in the regulation of the sleep/wake function. In particular, the posterior hypothalamus (PH) possesses several types of neurons, including the orexin neurons in the lateral hypothalamus (LH) with widespread projections to other wakefulness-related regions of the brain. Orexins have been known to affect feeding and appetite, and recently their profound effect on sleep disorders and DOC has been identified. Orexin antagonists are used for the treatment of insomnia, and orexin agonists can be used for narcolepsy. Additionally, several studies demonstrated that the agonists of orexin might be effective in the treatment of DOC, providing novel therapeutic opportunities in this field.

CONCLUSION

The hypothalamic-centered orexin has been adopted as the point of entry into the system of consciousness control, and modulators of orexin signaling opened several therapeutic opportunities for the treatment of DOC.

Resuscitating the Globally Ischemic Brain: TTM and Beyond

Cardiac arrest (CA) afflicts ~ 550,000 people each year in the USA. A small fraction of CA sufferers survive with a majority of these survivors emerging in a comatose state. Many CA survivors suffer devastating global brain injury with some remaining indefinitely in a comatose state. The pathogenesis of global brain injury secondary to CA is complex. Mechanisms of CA-induced brain injury include ischemia, hypoxia, cytotoxicity, inflammation, and ultimately, irreversible neuronal damage. Due to this complexity, it is critical for clinicians to have access as early as possible to quantitative metrics for diagnosing injury severity, accurately predicting outcome, and informing patient care. Current recommendations involve using multiple modalities including clinical exam, electrophysiology, brain imaging, and molecular biomarkers. This multi-faceted approach is designed to improve prognostication to avoid "self-fulfilling" prophecy and early withdrawal of life-sustaining treatments. Incorporation of emerging dynamic monitoring tools such as diffuse optical technologies may provide improved diagnosis and early prognostication to better inform treatment. Currently, targeted temperature management (TTM) is the leading treatment, with the number of patients needed to treat being ~ 6 in order to improve outcome for one patient. Future avenues of treatment, which may potentially be combined with TTM, include pharmacotherapy, perfusion/oxygenation targets, and pre/postconditioning. In this review, we provide a bench to bedside approach to delineate the pathophysiology, prognostication methods, current targeted therapies, and future directions of research surrounding hypoxic-ischemic brain injury (HIBI) secondary to CA.

The post-cardiac arrest syndrome: A case for lung-brain coupling and opportunities for neuroprotection

Systemic inflammation and multi-organ failure represent hallmarks of the post-cardiac arrest syndrome (PCAS) and predict severe neurological injury and often fatal outcomes. Current interventions for cardiac arrest focus on the reversal of precipitating cardiac pathologies and the implementation of supportive measures with the goal of limiting damage to at-risk tissue. Despite the widespread use of targeted temperature management, there remain no proven approaches to manage reperfusion injury in the period following the return of spontaneous circulation. Recent evidence has implicated the lung as a moderator of systemic inflammation following remote somatic injury in part through effects on innate immune priming. In this review, we explore concepts related to lung-dependent innate immune priming and its potential role in PCAS. Specifically, we propose and investigate the conceptual model of lung-brain coupling drawing from the broader literature connecting tissue damage and acute lung injury with cerebral reperfusion injury. Subsequently, we consider the role that interventions designed to short-circuit lung-dependent immune priming might play in improving patient outcomes following cardiac arrest and possibly other acute neurological injuries.

Orexin 2 receptor stimulation enhances resilience, while orexin 2 inhibition promotes susceptibility, to social stress, anxiety and depression

Knockdown of orexin/hypocretin 2 receptor (Orx₂) in the basolateral amygdala (BLA) affects anxious and depressive behavior. We use a new behavioral paradigm, the Stress Alternatives Model (SAM), designed to improve translational impact. The SAM induces social stress in adult male mice by aggression from larger mice, allowing for adaptive decision-making regarding escape. In this model, mice remain (Stay) in the oval SAM arena or escape from social aggression (Escape) via routes only large enough for the smaller mouse. We hypothesized intracerebroventricular (icv) stimulation of Orx₂ receptors would be anxiolytic and antidepressive in SAM-related social behavior and the Social Interaction/Preference (SIP) test. Conversely, we predicted that icv antagonism of Orx₂ receptors would promote anxious and depressive behavior in these same tests. Anxious behaviors such as freezing (both cued and conflict) and startle are exhibited more often in Stay compared with Escape phenotype mice. Time spent attentive to the escape route is more frequent in Escape mice. In Stay mice, stimulation of Orx₂ receptors reduces fear conditioning, conflict freezing and startle, and promotes greater attention to the escape hole. This anxiolysis was accompanied by activation of a cluster of inhibitory neurons in the amygdala. A small percentage of those Stay mice also begin escaping; whereas Escape is reversed by the Orx₂ antagonist. Escape mice were also Resilient, and Stay mice Susceptible to stress (SIP), with both conditions reversed by Orx₂ antagonism or stimulation respectively. Together, these results suggest that the Orx₂ receptor may be a useful potential target for anxiolytic or antidepressive therapeutics.

Therapeutic implications of how TNF links apolipoprotein E, phosphorylated tau, α-synuclein, amyloid-β and insulin resistance in neurodegenerative diseases

While cytokines such as TNF have long been recognized as essential to normal cerebral physiology, the implications of their chronic excessive production within the brain are now also increasingly appreciated. Syndromes as diverse as malaria and lead poisoning, as well as non‐infectious neurodegenerative diseases, illustrate this. These cytokines also orchestrate changes in tau, α‐synuclein, amyloid‐β levels and degree of insulin resistance in most neurodegenerative states. New data on the effects of salbutamol, an indirect anti‐TNF agent, on α‐synuclein and Parkinson's disease, APOE4 and tau add considerably to the rationale of the anti‐TNF approach to understanding, and treating, these diseases. Therapeutic advances being tested, and arguably useful for a number of the neurodegenerative diseases, include a reduction of excess cerebral TNF, whether directly, with a specific anti‐TNF biological agent such as etanercept via Batson's plexus, or indirectly via surgically implanting stem cells. Inhaled salbutamol also warrants investigating further across the neurodegenerative disease spectrum. It is now timely to integrate this range of new information across the neurodegenerative disease spectrum, rather than keep seeing it through the lens of individual disease states.