[Effects of Schisandrae Chinensis Fructus Lignans on Alertness of Rats With Sleep Deprived by Treadmill Exercise].

Objective To investigate the effects of Schisandrae Chinensis Fructus lignans on the alertness of the rats with sleep deprived by treadmill exercise and the underlying neurobiological mechanism. Methods According to the random number table method,SD male rats were assigned into control,sleep deprivation,low-,medium-,and high-dose Schisandrae Chinensis Fructus lignans,and atomoxetine hydrochloride groups,with 8 rats in each group.The rats in other groups except the control group were subjected to sleep deprivation by treadmill exercise for 3 d.During the deprivation period,each administration group was administrated with the corresponding drug by gavage,and a 5-9 hole tester was used to test the alertness performance of rats in each group. Furthermore,other SD male rats were selected and randomized into control,sleep deprivation,Schisandrae Chinensis Fructus lignans (67.2 mg/kg) and atomoxetine hydrochloride groups,with 10 rats in each group.The rats were modeled with the sleep deprivation method the same as that above and administrated with corresponding agents.ELISA was employed to measure the serum level of orexin A in each group of rats.The protein levels of c-Fos,orexin receptor 1,and orexin receptor 2 in the prefrontal cortex of rats in each group were observed by immunofluorescence and Western blotting. Results Compared with the control group,sleep deprivation reduced the choice accuracy (P<0.001) and increased the omission responses,omission percent,and mean correct response latency (P=0.002,P=0.003,P=0.020).Compared with the sleep deprivation group,medium- and high-dose Schisandrae Chinensis Fructus lignans and atomoxetine hydrochloride improved the alertness of rats,as demonstrated by the increased choice accuracy (P=0.001,P=0.006,P<0.001) and reduced omission responses (P=0.001,P=0.001,P<0.001),omission percent (P=0.001,P=0.002,P<0.001),and mean correct response latency (P=0.018,P=0.003,P=0.014).Compared with the control group,the sleep deprivation group showed elevated level of orexin A in the serum (P<0.001),up-regulated expression of c-Fos (P<0.001),and down-regulated expression of orexin receptor 1 (P=0.037) in the prefrontal cortex.Compared with the sleep deprivation group,Schisandrae Chinensis Fructus lignans (67.2 mg/kg) and atomoxetine hydrochloride lowered the orexin A level in the serum (P=0.005,P=0.029),down-regulated the expression of c-Fos (P=0.028,P=0.036),and up-regulated the expression of orexin receptor 1 (P=0.043,P=0.013) in the prefrontal cortex. Conclusion Schisandrae Chinensis Fructus lignans may antagonize the alertness decrease caused by sleep deprivation by regulating the secretion of orexin and the expression of orexin receptor 1 in the prefrontal cortex.

[Separation/Conversion Disorders in Functional Coma With Pseudocataplexy: Report of One Case and Literature Review].

Separation/conversion disorders in functional coma with pseudocataplexy are rare.On December 9,2021,a young female patient with separation/conversion disorders was treated in the Department of Neurology in the First Affiliated Hospital of Shandong First Medical University.The main symptoms were episodic consciousness disorders,sudden fainting,and urinary incontinence.Complete laboratory tests and cranial magnetic resonance imaging showed no obvious abnormalities.Standard multi-channel sleep monitoring and multiple sleep latency tests were performed.The patient was unable to wake up during nap and underwent stimulation tests.There was no response to orbital pressure,loud calls,or tapping,while the α rhythm in all electroencephalogram leads and the increased muscular tone in the mandibular electromyography indicated a period of wakefulness.The results of 24-hour sleep monitoring suggested that the patient had sufficient sleep at night and thus was easy to wake up in the morning.The results of daytime unrestricted sleep and wake-up test showed that the patient took one nap in the morning and one nap in the afternoon.When the lead indicated the transition from N3 to N2 sleep,a wake-up test was performed on the patient.At this time,the patient reacted to the surrounding environment and answered questions correctly.Because the level of orexin in the cerebrospinal fluid was over 110 pg/mL,episodic sleep disorder was excluded and the case was diagnosed as functional coma accompanied by pseudocataplexy.The patient did not present obvious symptom remission after taking oral medication,and thus medication withdrawl was recommended.Meanwhile,the patient was introduced to adjust the daily routine and mood.The follow-up was conducted six months later,and the patient reported that she did not experience similar symptoms after adjusting lifestyle.Up to now,no similar symptoms have appeared in multiple follow-up visits for three years.Functional coma with pseudocataplexy is prone to misdiagnosis and needs to be distinguished from true coma and episodic sleep disorders.

Reduced plasma interleukin-6 concentration after transcranial direct current stimulation to the prefrontal cortex.

OBJECTIVES: Transcranial direct stimulation (tDCS) targeted to the dorsolateral prefrontal cortex (DLPFC) reduces food intake and hunger, but its effects on circulating factors are unclear. We assessed the effect of repeated administration of tDCS to the left DLPFC (L-DLPFC) on concentrations of pro/anti-inflammatory and appetitive hormone concentrations. MATERIALS AND METHODS: Twenty-nine healthy adults with obesity (12 M; 42±11 y; BMI=39±8 kg/m2) received 3 consecutive inpatient sessions of either anodal or sham tDCS targeted to the L-DLPFC during a period of ad libitum food intake. Fasting plasma concentrations of IL-6, orexin, cortisol, TNF-α, IL-1ß, ghrelin, PYY, and GLP-1 were measured before the initial and after the final tDCS sessions. RESULTS: IL-6 (ß=-0.92 pg/ml p=0.03) decreased in the anodal group compared with sham, even after adjusting for kcal intake; there were no changes in other hormones. Mean kcal intake was associated with higher IL-1ß and ghrelin concentrations after the ad libitum period (ß=0.00018 pg/ml/kcal, p=0.03; ß=0.00011 pg/ml/kcal, p=0.02; respectively), but not differ by intervention groups. CONCLUSIONS: IL-6 concentrations were reduced following anodal tDCS to the L-DLPFC independent of ad libitum intake. IL-6 concentrations reflect the inflammatory state of adiposity and may affect eating behavior and weight gain. These findings provide evidence of therapeutic benefit of tDCS.

Orexin-mediated motivated arousal and reward seeking.

The neuromodulator orexin has been identified as a key factor for motivated arousal including recent evidence that sleep deprivation-induced enhancement of reward behavior is modulated by orexin. While orexin is not necessary for either reward or arousal behavior, orexin neurons' broad projections, ability to sense the internal state of the animal, and high plasticity of signaling in response to natural rewards and drugs of abuse may underlie heightened drug seeking, particularly in a subset of highly motivated reward seekers. As such, orexin receptor antagonists have gained deserved attention for putative use in addiction treatments. Ongoing and future clinical trials are expected to identify individuals most likely to benefit from orexin receptor antagonist treatment to promote abstinence, such as those with concurrent sleep disorders or high craving, while attention to methodological considerations will aid interpretation of the numerous preclinical studies investigating disparate aspects of the role of orexin in reward and arousal.

Exploring the association between hypocretin-1 levels and bone mineral content in patients with narcolepsy: A cross-sectional study.

INTRODUCTION: Recent studies suggest the existence of a physiologic basis for bone rarefaction and increased risk for fractures. This study aimed to address anthropometric differences between patients with narcolepsy type 1 (NT1) and type 2 (NT2) and discrepancies in bone mineral content (BMC) as a function of hypocretin-1 (Hcrt-1) measured in cerebrospinal fluid (CSF). METHODS: We have evaluated 31 adult patients (aged 18-65 years) with NT1 and 18 patients with NT2, comparing the groups in terms of anthropometric variables - body mass index (BMI) and waist-to-hip ratio (WHR) - and percentage of bone mineral content (%BMC), measured by bioelectrical impedance analysis (BIA). Statistical analysis assessed the effects of Hcrt-1 levels on CSF, dietary intake, and medication use over these variables. Statistical significance was achieved with a confidence interval of 95 % and p < 0.05. RESULTS: Patients with NT1 presented with higher BMI (32.04 ± 6.95 vs. 25.38 ± 4.26 kg/m2; p < 0.01) and WHR (0.89 ± 0.09 vs. 0.83 ± 0.09; p = 0.02) compared to NT2, in detriment of %BMC, which was lower for NT1 (4.1 ± 1.02 vs. 4.89 ± 0.59; p < 0.01). Hcrt-1 in CSF showed a positive correlation with %BMC (r = +0.48, p < 0.01) and a negative correlation with anthropometric features (BMI: r = -0.54, p < 0.01; WHR: r = -0.37, p = 0.01). There was a correlation between WHR and diary caloric intake (r = +0.42, p < 0.01). CONCLUSION: The evaluation of patients with narcolepsy presupposes a syndromic approach comprising symptoms that go far beyond excessive daytime sleepiness. The integrated follow-up, including nutritional profile and anthropometric features, should add value in reducing morbidity in this population.

In vivo photocontrol of orexin receptors with a nanomolar light-regulated analogue of orexin-B.

Orexinergic neurons are critically involved in regulating arousal, wakefulness, and appetite. Their dysfunction has been associated with sleeping disorders, and non-peptide drugs are currently being developed to treat insomnia and narcolepsy. Yet, no light-regulated agents are available to reversibly control their activity. To meet this need, a photoswitchable peptide analogue of the endogenous neuroexcitatory peptide orexin-B was designed, synthesized, and tested in vitro and in vivo. This compound - photorexin - is the first photo-reversible ligand reported for orexin receptors. It allows dynamic control of activity in vitro (including almost the same efficacy as orexin-B, high nanomolar potency, and subtype selectivity to human OX2 receptors) and in vivo in zebrafish larvae by direct application in water. Photorexin induces dose- and light-dependent changes in locomotion and a reduction in the successive induction reflex that is associated with sleep behavior. Molecular dynamics calculations indicate that trans and cis photorexin adopt similar bent conformations and that the only discriminant between their structures and activities is the positioning of the N-terminus. This, in the case of the more active trans isomer, points towards the OX2 N-terminus and extra-cellular loop 2, a region of the receptor known to be involved in ligand binding and recognition consistent with a "message-address" system. Thus, our approach could be extended to several important families of endogenous peptides, such as endothelins, nociceptin, and dynorphins among others, that bind to their cognate receptors through a similar mechanism: a "message" domain involved in receptor activation and signal transduction, and an "address" sequence for receptor occupation and improved binding affinity.

A high-fat diet induced depression-like phenotype via hypocretin-HCRTR1 mediated inflammation activation.

Background: A high-fat diet (HFD) is generally associated with an increased risk of mental disorders that constitute a sizeable worldwide health. A HFD results in the gut microbiota-brain axis being altered and linked to mental disorders. Hypocretin-1, which can promote appetite, has been previously confirmed to be associated with depression. However, no exact relationship has been found for hypocretin between depression and HFDs. Methods: Adult male SD rats were randomly assigned to either a HFD or a normal diet for eight weeks, followed by behavioral tests and plasma biochemical analyses. Then, we investigated the protein and mRNA levels of inflammation-related factors in the hippocampus. We also observed morphological changes in brain microglia and lipid accumulation. Additionally, metagenomic and metabolomic analyses of gut microbiomes were performed. 3T3-L1 cells were utilized in vitro to investigate the impact of hypocretin receptor 1 antagonists (SB334867) on lipid accumulation. To consider the connection between the brain and adipose tissue, we used a conditioned medium (CM) treated with 3T3-L1 cells to observe the activation and phagocytosis of BV2 cells. Following a 12-week period of feeding a HFD to C57BL/6 mice, a three-week intervention period was initiated during which the administration of SB334867 was observed. This was followed by a series of assessments, including monitoring of body weight changes and emotional problems, as well as attention to plasma biochemical levels and microglial cell phenotypes in the brain. Results: The HFD rats displayed anxiety and depressive-like behaviors. HFD rats exhibited increased plasma HDL, LDL, and TC levels. A HFD also causes an increase in hypocretin-1 and hypocretin-2 in the hypothalamus. Metagenomics and metabolomics revealed that the HFD caused an increase in the relative abundance of associated inflammatory bacteria and decreased the abundance of anti-inflammatory and bile acid metabolites. Compared with the CTR group, hippocampal microglia in the HFD group were significantly activated and accompanied by lipid deposition. At the same time, protein and mRNA expression levels of inflammation-related factors were increased. We found that SB334867 could significantly reduce lipid accumulation in 3T3-L1 cells after differentiation. The expression of inflammatory factors decreased in the SB334867 group. The administration of SB334867 was found to reverse the adverse effects of the HFD on body weight, depressive-like behaviour and anxiety-like mood. Furthermore, this treatment was associated with improvements in plasma biochemical levels and a reduction in the number of microglia in the brain. Conclusions: In summary, our results demonstrated that a HFD induced anxiety and depressive-like behaviors, which may be linked to the increased hypocretin-1 level and lipid accumulation. Supplementation with SB334867 improved the above. These observations highlight the possibility of hypocretin-1 inducing the risk of HFD-associated emotional dysfunctions.

Orexin and Sleep Disturbances in Alpha-Synucleinopathies: a Systematic Review.

PURPOSE OF REVIEW: Sleep disturbances are amongst most frequent non-motor symptoms of Parkinson's Disease (PD), and they are similarly frequently reported in other alpha-syncleinopathies, such as Dementia with Lewy Bodies (DLB) and Multiple System Atrophy (MSA). More recently, the orexin system has been implicated in control of arousal based on salient environmental set points, and its dysregulation in sleep issues in alpha-synucleinopathies suggested by the findings from the translational animal models. However, its role in the patients with alpha-synucleinopathies remains unclear. We thus set to systematically review, and to critically assess, contemporary evidence on the association of the orexinergic system and sleep disturbances in alpha-synucleinopathies. In this systematic review, studies investigating orexin and sleep in alpha-synucleinopathies (Rapid Eye Movement (REM) Behaviour Disorder (RBD), Parkinson's Disease (PD), Dementia with Lewy Bodies (DLB), Multiple System Atrophy (MSA)) were identified using electronic database searches of PubMed, Web of Science and PsychINFO using MeSH terms, keywords, and title words such as "Alpha-synucleinopathies" AND "Orexin" AND "Sleep Disturbances". RECENT FINDINGS: 17 studies were included in this systemic review, of which 2 studies on RBD, 10 on PD, 4 on DLB, and 1 on MSA patients. Taken together, RBD and PD studies suggest a potential adaptive increase in orexin levels in early stages of the neurodegenerative process, with reduced levels more often reported for later, more advanced stages of illness. To date, no differences in orexin levels were demonstrated between MSA patients and healthy controls. There is a dearth of studies on the role of orexin levels in alpha-synucleinopathies. Moreover, significant methodologic limitations in the current body of work, including use of non-standardised research protocols and lack of prospective, multi-centre studies, disallow for any finite conclusion in regards to underlying pathomechanisms. Nonetheless, a picture of a complex, multifaceted relationship between the dysregulation of the orexinergic pathway and sleep disturbances in alpha-synucleinopathies is emerging. Hence, future studies disentangling orexinergic pathomechanisms of alpha-syncleinopathies are urgently needed to obtain a more comprehensive account of the role of orexinergic pathway in alpha-synucleinopathies. Pharmacological manipulations of orexins may have multiple therapeutic applications in treatment strategies, disease diagnosis, and might be effective for treating both motor and non-motor symptoms.

Infection, vaccination and narcolepsy type 1: Evidence and potential molecular mechanisms.

NT1 is a rare, chronic and disabling neurological disease causing excessive daytime sleepiness and cataplexy. NT1 is characterized pathologically by an almost complete loss of neurons producing the hypocretin (HCRT)/orexin neuropeptides in the lateral hypothalamus. While the exact etiology of NT1 is still unknown, numerous studies have provided compelling evidence supporting its autoimmune origin. The prevailing hypothetical view on the pathogenesis of NT1 involves an immune-mediated loss of HCRT neurons that can be triggered by Pandemrix® vaccination and/or by infection in genetically susceptible patients, specifically carriers of the HLA-DQB1*06:02 MHC class II allele. The molecular mechanisms by which infection/vaccination can induce autoimmunity in the case of NT1 remain to be elucidated. In this review, evidence regarding the involvement of vaccination and infection and the potential mechanisms by which it could be linked to the pathogenesis of NT1 will be discussed in light of the existing findings in other autoimmune diseases.

Sleep quality in patients with chronic spontaneous urticaria and relation with Orexin-A, leptin, and ghrelin.

Background: Sleep can be affected in patients with chronic spontaneous urticaria (CSU). The mechanisms of sleep regulation remain poorly understood. Orexin-A, a neuroexcitatory peptide, plays a role in coordinating sleep-wake states. Ghrelin and leptin are involved in sleep regulation through the orexin system. Objective: The effects of orexin-A, ghrelin, and leptin on sleep quality in patients with CSU have not been investigated. We aimed to determine the effects of CSU on sleep quality and the association between serum orexin-A, ghrelin, and leptin levels, and sleep quality in patients with CSU. Methods: Thirty-three patients with CSU and 34 sex- and age-matched controls were included in the study. Serum orexin-A, leptin, and ghrelin levels, and the Pittsburgh Sleep Quality Index (PSQI) and the Epworth Sleepiness Scale (ESS) scores were measured in patients with CSU and in the controls; also used were the chronic urticaria quality-of-life questionnaire score and the urticaria activity score used for 7 consecutive days. Results: Median (minimum-maximum) orexin-A, leptin, and ghrelin levels in patients were 385 pg/mL (90-495 pg/mL), 3.1 ng/mL (0-21.2 ng/mL), and 701.8 pg/mL (101.9-827.7 pg/mL), respectively. Median serum orexin-A and leptin levels were higher in the patients compared with the controls (p < 0.001 and p = 0.012, respectively), whereas the median serum ghrelin levels were similar to the controls (p = 0.616). The serum orexin-A level was positively correlated with ghrelin (r = 0.298, p = 0.014), PSQI sleep quality (r = 0.356, p = 0.003), and ESS (r = 0.357, p = 0.003). Conclusion: Serum orexin-A is associated with sleep quality in patients with CSU. Further studies are needed to elucidate the role of ghrelin and leptin on sleep quality in patients with CSU.

Astrocytic metabolic control of orexinergic activity in the lateral hypothalamus regulates sleep and wake architecture.

Neuronal activity undergoes significant changes during vigilance states, accompanied by an accommodation of energy demands. While the astrocyte-neuron lactate shuttle has shown that lactate is the primary energy substrate for sustaining neuronal activity in multiple brain regions, its role in regulating sleep/wake architecture is not fully understood. Here we investigated the involvement of astrocytic lactate supply in maintaining consolidated wakefulness by downregulating, in a cell-specific manner, the expression of monocarboxylate transporters (MCTs) in the lateral hypothalamus of transgenic mice. Our results demonstrate that reduced expression of MCT4 in astrocytes disrupts lactate supply to wake-promoting orexin neurons, impairing wakefulness stability. Additionally, we show that MCT2-mediated lactate uptake is necessary for maintaining tonic firing of orexin neurons and stabilizing wakefulness. Our findings provide both in vivo and in vitro evidence supporting the role of astrocyte-to-orexinergic neuron lactate shuttle in regulating proper sleep/wake stability.

Neurochemical and genetic factors in panic disorder: a systematic review.

This systematic review addresses the complex nature of Panic Disorder (PD), characterized by recurrent episodes of acute fear, with a focus on updating and consolidating knowledge regarding neurochemical, genetic, and epigenetic factors associated with PD. Utilizing the PRISMA methodology, 33 original peer-reviewed studies were identified, comprising 6 studies related to human neurochemicals, 10 related to human genetic or epigenetic alterations, and 17 animal studies. The review reveals patterns of altered expression in various biological systems, including neurotransmission, the Hypothalamic-Pituitary-Adrenal (HPA) axis, neuroplasticity, and genetic and epigenetic factors leading to neuroanatomical modifications. Noteworthy findings include lower receptor binding of GABAA and serotonin neurotransmitters in the amygdala. The involvement of orexin (ORX) neurons in the dorsomedial/perifornical region in triggering panic reactions is highlighted, with systemic ORX-1 receptor antagonists blocking panic responses. Elevated Interleukin 6 and leptin levels in PD patients suggest potential connections between stress-induced inflammatory changes and PD. Brain-derived neurotrophic factor (BDNF) and tyrosine receptor kinase B (TrkB) signaling are implicated in panic-like responses, particularly in the dorsal periaqueductal gray (dPAG), where BDNF's panicolytic-like effects operate through GABAA-dependent mechanisms. GABAergic neurons' inhibitory influence on dorsomedial and posterior hypothalamus nuclei is identified, potentially reducing the excitability of neurons involved in panic-like responses. The dorsomedial hypothalamus (DMH) is highlighted as a specific hypothalamic nucleus relevant to the genesis and maintenance of panic disorder. Altered brain lactate and glutamate concentrations, along with identified genetic polymorphisms linked to PD, further contribute to the intricate neurochemical landscape associated with the disorder. The review underscores the potential impact of neurochemical, genetic, and epigenetic factors on the development and expression of PD. The comprehensive insights provided by this systematic review contribute to advancing our understanding of the multifaceted nature of Panic Disorder and pave the way for targeted therapeutic strategies.

Altered ventilatory responses to hypercapnia-hypoxia challenges in a preclinical SUDEP model involve orexin neurons.

Failure to recover from repeated hypercapnia and hypoxemia (HH) challenges caused by severe GCS and postictal apneas may contribute to sudden unexpected death in epilepsy (SUDEP). Our previous studies found orexinergic dysfunction contributes to respiratory abnormalities in a preclinical model of SUDEP, Kcna1-/- mice. Here, we developed two gas challenges consisting of repeated HH exposures and used whole body plethysmography to determine whether Kcna1-/- mice have detrimental ventilatory responses. Kcna1-/- mice exhibited an elevated ventilatory response to a mild repeated hypercapnia-hypoxia (HH) challenge compared to WT. Moreover, 71% of Kcna1-/- mice failed to survive a severe repeated HH challenge, whereas all WT mice recovered. We next determined whether orexin was involved in these differences. Pretreating Kcna1-/- mice with a dual orexin receptor antagonist rescued the ventilatory response during the mild challenge and all subjects survived the severe challenge. In ex vivo extracellular recordings in the lateral hypothalamus of coronal brain slices, we found reducing pH either inhibits or stimulates putative orexin neurons similar to other chemosensitive neurons; however, a significantly greater percentage of putative orexin neurons from Kcna1-/-mice were stimulated and the magnitude of stimulation was increased resulting in augmentation of the calculated chemosensitivity index relative to WT. Collectively, our data suggest that increased chemosensitive activity of orexin neurons may be pathologic in the Kcna1-/- mouse model of SUDEP, and contribute to elevated ventilatory responses. Our preclinical data suggest that those at high risk for SUDEP may be more sensitive to HH challenges, whether induced by seizures or other means; and the depth and length of the HH exposure could dictate the probability of survival.

Baseline circulating biomarkers, their changes, and subsequent suicidal ideation and depression severity at 6 months: A prospective analysis in patients with mood disorders.

BACKGROUND: Identifying circulating biomarkers associated with prospective suicidal ideation (SI) and depression could help better understand the dynamics of these phenomena and identify people in need of intense care. In this study, we investigated the associations between baseline peripheral biomarkers implicated in neuroplasticity, vascular homeostasis and inflammation, and prospective SI and depression severity during 6 months of follow-up in patients with mood disorders. METHODS: 149 patients underwent a psychiatric evaluation and gave blood to measure 32 plasma soluble proteins. At follow-up, SI incidence over six months was measured with the Columbia Suicide Severity Rating Scale, and depressive symptoms were assessed with the Inventory for Depressive Symptomatology. Ninety-six patients provided repeated blood samples. Statistical analyses included Spearman partial correlation and Elastic Net regression, followed by the covariate-adjusted regression models. RESULTS: 51.4 % (N = 71) of patients reported SI during follow-up. After adjustment for covariates, higher baseline levels of interferon-γ were associated with SI occurrence during follow-up. Higher baseline interferon-γ and lower orexin-A were associated with increased depression severity, and atypical and anxious, but not melancholic, symptoms. There was also a tendency for associations of elevated baseline levels of interferon-γ, interleukin-1ß, and lower plasma serotonin levels with SI at the six-month follow-up time point. Meanwhile, reduction in transforming growth factor- ß1 (TGF-ß1) plasma concentration correlated with atypical symptoms reduction. CONCLUSION: We identified interferon-γ and orexin-A as potential predictive biomarkers of SI and depression, whereas TGF-ß1 was identified as a possible target of atypical symptoms.

CSF dynamics of orexin and ß-amyloid42 levels in narcolepsy and Alzheimer's disease patients: a controlled study.

ß-amyloid42 (Aß42) in Alzheimer's disease (AD) and orexin in narcolepsy are considered crucial biomarkers for diagnosis and therapeutic targets. Recently, orexin and Aß cerebral dynamics have been studied in both pathologies, but how they interact with each other remains further to be known. In this study, we investigated the reliability of using the correlation between orexin-A and Aß42 CSF levels as a candidate marker to explain the chain of events leading to narcolepsy or AD pathology. In order to test the correlation between these biomarkers, patients diagnosed with AD (n = 76), narcolepsy type 1 (NT1, n = 17), narcolepsy type 2 (NT2, n = 23) and healthy subjects (n = 91) were examined. Patients and healthy subjects underwent lumbar puncture between 8:00 and 10:00 am at the Neurology Unit of the University Hospital of Rome "Tor Vergata". CSF levels of Aß42, total-tau, phosphorylated-tau, and orexin-A were assessed. The results showed that CSF levels of Aß42 were significantly lower (p < 0.001) in AD (332.28 ± 237.36 pg/mL) compared to NT1 (569.88 ± 187.00 pg/mL), NT2 (691.00 ± 292.63 pg/mL) and healthy subjects (943.68 ± 198.12 pg/mL). CSF orexin-A levels were statistically different (p < 0.001) between AD (148.01 ± 29.49 pg/mL), NT1 (45.94 ± 13.63 pg/mL), NT2 (104.92 ± 25.55 pg/mL) and healthy subjects (145.18 ± 27.01 pg/mL). Moderate-severe AD patients (mini mental state examination < 21) showed the highest CSF orexin-A levels, whereas NT1 patients showed the lowest CSF orexin-A levels. Correlation between CSF levels of Aß42 and orexin-A was found only in healthy subjects (r = 0.26; p = 0.01), and not in narcolepsy or AD patients. This lack of correlation in both diseases may be explained by the pathology itself since the correlation between these two biomarkers is evident only in the healthy subjects. This study adds to the present literature by further documenting the interplay between orexinergic neurotransmission and cerebral Aß dynamics, possibly sustained by sleep.

Effect of optogenetic excitation of non-orexinergic neurons in the hypothalamic perifornical area on motor behaviors and cardiovascular parameters in rats.

Central command, a motor volition originating in the rostral part of the brain, plays a pivotal role in the precise regulation of autonomic nervous and cardiovascular systems. Central neuronal substrates responsible for transmitting central command signals remain incompletely understood. This study aimed to investigate the effect of optogenetic excitation of non-orexinergic (NOrx) neurons in the hypothalamic perifornical area (PeFA), where orexinergic neurons are densely distributed, on motor behaviors and cardiovascular parameters in rats. An adeno-associated viral serotype 2 vector carrying the human synapsin promoter encoding channelrhodopsin 2 (ChR2) fused to EYFP was injected into the PeFA of Sprague-Dawley rats, resulting in selective expression of ChR2-EYFP in NOrx PeFA neurons. In conscious rats, optogenetic excitation of NOrx PeFA neurons rapidly elicited walking or biting behavior, simultaneously causing pressor and tachycardiac responses regardless of the observed behavioral patterns. Under anesthesia, this excitation rapidly increased renal sympathetic nerve activity, immediately followed by sympathoinhibition. These findings suggest that NOrx PeFA neurons transmit central command signals, concurrently regulating somatomotor and autonomic nervous systems for locomotor exercise or biting behavior.

Restraint stress-induced antinociceptive effects in acute pain: Involvement of orexinergic system in the nucleus accumbens.

The complicated relevance between stress and pain has been identified. Neurotransmitters and neuropeptides of various brain areas play a role in this communication. Pain inhibitory response is known as stress-induced analgesia (SIA). The studies demonstrated that the nucleus accumbens (NAc) is critical in modulating pain. As a neuropeptide, orexin is crucially involved in initiating behavioral and physiological responses to threatening and unfeeling stimuli. However, the role of the orexin receptors of the NAc area after exposure to restraint stress (RS) as acute physical stress in the modulation of acute pain is unclear. One hundered twenty adult male albino Wistar rats (230-250 g) were used. Animals were unilaterally implanted with cannulae above the NAc. The SB334867 and TCS OX2 29 were used as antagonists for OX1r and OX2r, respectively. Different doses of the antagonists (1, 3, 10, and 30 nmol/0.5 µl DMSO) were microinjected intra-NAc five minutes before exposure to RS (3 hours). Then, the tail-flick test as a model of acute pain was performed, and the nociceptive threshold (Tail-flick latency; TFL) was measured in 60-minute time set intervals. According to this study's findings, the antinociceptive effects of RS in the tail-flick test were blocked during intra-NAc administration of SB334867 or TCS OX2 29. The RS as acute stress increased TFL and deceased pain-like behavior responses. The 50 % effective dose values of the OX1r and OX2r antagonists were 12.82 and 21.64 nmol, respectively. The result demonstrated contribution of the OX1r into the NAc was more remarkable than that of the OX2r on antinociceptive responses induced by the RS. Besides, in the absence of RS, the TFL was attenuated. The current study's data indicated that OX1r and OX2r into the NAc induced pain modulation responses during RS in acute pain. In conclusion, the findings revealed the involvement of intra-NAc orexin receptors in improving SIA.

Evaluating routine blood and cerebrospinal fluid samples in narcolepsy patients.

Cerebrospinal fluid hypocretin-1 is proven to be a precise diagnostic marker of narcolepsy Type 1 (NT1). However other characteristics of cerebrospinal fluid and blood parameters have not yet been described. The objective of this study was to evaluate the differences in routine blood and cerebrospinal fluid analyses between NT1 patients and patients suspected of hypersomnia. We collected retrospectively all measures of cerebrospinal fluid hypocretin-1 between 2019 and 2022. This yielded 612 patients out of which 146 were diagnosed with NT1 and the rest (466 patients) were used as a control group. We selected the most relevant routine samples from both blood, plasma and cerebrospinal fluid and compared the two groups. The only significantly different analytes were plasma lactate dehydrogenase and cerebrospinal fluid hypocretin-1. No other differences were found between the groups including thyroid markers, markers of neuroendocrine function, inflammatory markers in blood or cerebrospinal fluid, markers of permeability of the blood brain barrier or metabolic markers in blood samples. We found no significant differences in routine blood or cerebrospinal fluid components, neuroendocrine function, neuroinflammation and metabolic markers. The results reflect that the hypocretin system does not seem to play a chronic major role in regulation of these markers. None of the parameters routinely measured in blood in these patients could differentiate between NT1 and non-NT1 disorders besides CSF-hcrt-1.

Pivotal role of orexin signaling in the posterior paraventricular nucleus of the thalamus during the stress-induced reinstatement of oxycodone-seeking behavior.

BACKGROUND: The orexin (OX) system has received increasing interest as a potential target for treating substance use disorder. OX transmission in the posterior paraventricular nucleus of the thalamus (pPVT), an area activated by highly salient stimuli that are both reinforcing and aversive, mediates cue- and stress-induced reinstatement of reward-seeking behavior. Oral administration of suvorexant (SUV), a dual OX receptor (OXR) antagonist (DORA), selectively reduced conditioned reinstatement of oxycodone-seeking behavior and stress-induced reinstatement of alcohol-seeking behavior in dependent rats. AIMS: This study tested whether OXR blockade in the pPVT with SUV reduces oxycodone or sweetened condensed milk (SCM) seeking elicited by conditioned cues or stress. METHODS: Male Wistar rats were trained to self-administer oxycodone (0.15 mg/kg, i.v., 8 h/day) or SCM (0.1 ml, 2:1 dilution [v/v], 30 min/day). After extinction, we tested the ability of intra-pPVT SUV (15 µg/0.5 µl) to prevent reinstatement of oxycodone or SCM seeking elicited by conditioned cues or footshock stress. RESULTS: The rats acquired oxycodone and SCM self-administration, and oxycodone intake correlated with signs of physical opioid withdrawal, confirming dependence. Following extinction, the presentation of conditioned cues or footshock elicited reinstatement of oxycodone- and SCM-seeking behavior. Intra-pPVT SUV blocked stress-induced reinstatement of oxycodone seeking but not conditioned reinstatement of oxycodone or SCM seeking or stress-induced reinstatement of SCM seeking. CONCLUSIONS: The results indicate that OXR signaling in the pPVT is critical for stress-induced reinstatement of oxycodone seeking, further corroborating OXRs as treatment targets for opioid use disorder.

Graph convolutional network with attention mechanism improve major depressive depression diagnosis based on plasma biomarkers and neuroimaging data.

BACKGROUND: The absence of clinically-validated biomarkers or objective protocols hinders effective major depressive disorder (MDD) diagnosis. Compared to healthy control (HC), MDD exhibits anomalies in plasma protein levels and neuroimaging presentations. Despite extensive machine learning studies in psychiatric diagnosis, a reliable tool integrating multi-modality data is still lacking. METHODS: In this study, blood samples from 100 MDD and 100 HC were analyzed, along with MRI images from 46 MDD and 49 HC. Here, we devised a novel algorithm, integrating graph neural networks and attention modules, for MDD diagnosis based on inflammatory cytokines, neurotrophic factors, and Orexin A levels in the blood samples. Model performance was assessed via accuracy and F1 value in 3-fold cross-validation, comparing with 9 traditional algorithms. We then applied our algorithm to a dataset containing both the aforementioned protein quantifications and neuroimages, evaluating if integrating neuroimages into the model improves performance. RESULTS: Compared to HC, MDD showed significant alterations in plasma protein levels and gray matter volume revealed by MRI. Our new algorithm exhibited superior performance, achieving an F1 value and accuracy of 0.9436 and 94.08 %, respectively. Integration of neuroimaging data enhanced our novel algorithm's performance, resulting in an improved F1 value and accuracy, reaching 0.9543 and 95.06 %. LIMITATIONS: This single-center study with a small sample size requires future evaluations on a larger test set for improved reliability. CONCLUSIONS: In comparison to traditional machine learning models, our newly developed MDD diagnostic model exhibited superior performance and showed promising potential for inclusion in routine clinical diagnosis for MDD.