Increased serum brain-derived neurotrophic factor (BDNF) levels in patients with narcolepsy

The Relationship between Sleep Parameters Measured by Polysomnography and Selected Neurotrophic Factors

BACKGROUND

The molecular underpinnings of insufficient sleep remain underexplored, with disruptions in the neurotrophic signaling pathway emerging as a potential explanation. Neurotrophins (NTs), including brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3), neurotrophin 4 (NT4), and glial-cell-line-derived growth factor (GDNF), play crucial roles in nerve cell growth and repair. However, their associations with sleep patterns are poorly understood. This study aimed to investigate the relationship between the chosen neurotrophins and objective sleep parameters.

METHODS

The study involved 81 participants subjected to polysomnography (PSG). Blood samples were collected after PSG. The mRNA expression and serum protein concentrations of BDNF, GDNF, NT3, and NT4 were measured using real-time quantitative reverse-transcription PCR (qRT-PCR) or enzyme-linked immunosorbent assay (ELISA) methods, respectively.

RESULTS

BDNF and NT3 proteins were negatively correlated with NREM events, while NT4 protein positively correlated with REM events. Electroencephalography power analysis revealed BDNF protein's negative correlation with delta waves during rapid eye movement and non-rapid eye movement sleep.

CONCLUSION

The study highlights associations between neurotrophins and sleep, emphasizing BDNF's role in regulating NREM and REM sleep. The EEG power analysis implicated BDNF in delta wave modulation, shedding light on potential neurotrophic mechanisms underlying sleep effects on cognitive and mood processes.

Increased plasma brain-derived neurotrophic factor (BDNF) as a potential biomarker for and compensatory mechanism in mild cognitive impairment: a case-control study

Background: Previous meta-analyses examining the continuum of Alzheimer’s disease (AD) concluded significantly decreased peripheral brain-derived neurotrophic factor (BDNF) in AD. However, across different meta-analyses, there remain inconsistent findings on peripheral BDNF levels in individuals with mild cognitive impairment (MCI). This issue has been attributed to the highly heterogenous clinical and laboratory factors. Thus, BDNF’s level, discriminative accuracy for identifying all-cause MCI and its subtypes, and its associations with other biomarkers and neurocognitive domains, remain largely unknown.

Methods: To address this heterogeneity, we compared a healthy control cohort (n=56, 45 female) to an MCI cohort (n=40, 28 female), to determine whether plasma BDNF, hs-CRP, and DHEA-S can differentiate healthy from MCI individuals, including two MCI subtypes (amnestic [aMCI] and non-amnestic [non-aMCI]). The associations between BDNF with other biomarkers and neurocognitive tests were examined. Adults with cerebral palsy were included as sensitivity analyses.

Results: Compared to healthy controls, BDNF was significantly higher in all-cause MCI, aMCI, and non-aMCI. Furthermore, BDNF had good (AUC=0.84, 95% CI=0.74 to 0.95, p<0.001) and excellent discriminative accuracies (AUC=0.92, 95% CI=0.84 to 1.00, p<0.001) for all-cause MCI and non-amnestic MCI, respectively. BDNF was significantly and positively associated with plasma hs-CRP (β=0.26, 95% CI=0.02 to 0.50, p=0.038), despite attenuated association upon controlling for BMI (β=0.15, 95% CI=-0.08 to 0.38, p=0.186). Multiple inverse associations between BDNF and detailed neurocognitive tests were also detected.

Conclusions: These findings suggest BDNF is increased as a compensatory mechanism in preclinical dementia, supporting the neurotrophic and partially the inflammatory hypotheses of cognitive impairment.

Influence of excessive daily sleeping and sleep quality on BDNF and NGF serum levels in adolescents

INTRODUCTION

The brain-derived neurotrophic factor (BDNF) and neural growth factor (NGF) are widely expressed in the brain and play an important role in neuroplasticity, neurogenesis, and increased neuronal connections. Previous studies have shown that reduced serum levels of these proteins are associated with disorders in human sleep.

OBJECTIVE

Current study evaluates the prevalence in adolescents of excessive daytime sleepiness (EDS) and sleep quality, and analyzes the influence of these factors on BDNF and NGF serum levels.

METHODS

A cross-section population-based study was conducted with data from a Brazilian birth cohort, with a sample of five hundred and thirteen 18-19-year-old adolescents. Sleep quality was assessed by the Pittsburgh Sleep Quality Index and EDS by Epworth Sleepiness Scale. Neurotrophins serum levels were measured by Luminex™ technology kits. Analysis consisted of marginal structural models which compared people who were exposed and not exposed to sleep quality and EDS.

RESULTS

Poor sleep quality and EDS were detected in 62.57% and 36.35% of the sample. Adolescents with poor sleep quality and EDS had -0.39 (p-value = 0.049) and -0.51 pg/ml in NGF (p-value = 0.009). Individuals with self-reported sleep disorder had lower serum levels of NGF (Coef. -0.41, p-value = 0.045).

CONCLUSION

High prevalence of EDS and low sleep quality in a population of adolescents were evidenced. Poor sleep quality and EDS were associated with lower NGF levels, whilst adolescents with self-reported sleep disorder had lower serum levels of NGF.

Constructing gene network for type 1 narcolepsy based on genome-wide association study and differential gene expression analysis (STROBE)

Although many genes that affect narcolepsy risk have been identified, the interactions among these genes are still unclear. Moreover, there is a lack of research on the construction of the genetic network of narcolepsy. To screen candidate genes related to the onset of narcolepsy type 1, the function and distribution of important genes related to narcolepsy type 1 were studied and a gene network was constructed to study the pathogenesis of narcolepsy type 1.A case-control study (observational study) of 1075 Chinese narcoleptic patients and 1997 controls was conducted. The gene-sequencing data was analyzed using genome-wide association analysis. The candidate genes related to narcolepsy were identified by differential gene expression analysis and literature research. Then, the 28 candidate genes were input into the KEGG database and 32 pathway data related to candidate genes were obtained. A gene network, with the pathways as links and the genes as nodes, was constructed. According to our results, TNF, MHC II, NFATC2, and CXCL8 were the top genes in the gene network.TNF, MHC II, NFATC2, and CXCL8 are closely related to narcolepsy type I and require further study. By analyzing the pathways of disease-related genes and the network of gene interaction, we can provide an outlinefor the study of specific mechanisms of and treatments for narcolepsy.

Changes in Cortisol but Not in Brain-Derived Neurotrophic Factor Modulate the Association Between Sleep Disturbances and Major Depression

Sleep disturbance is a symptom consistently found in major depression and is associated with a longer course of illness, reduced response to treatment, increased risk of relapse and recurrence. Chronic insomnia has been associated with changes in cortisol and serum brain-derived neurotrophic factor (BDNF) levels, which in turn are also changed in major depression. Here, we evaluated the relationship between sleep quality, salivary cortisol awakening response (CAR), and serum BDNF levels in patients with sleep disturbance and treatment-resistant major depression (n = 18), and in a control group of healthy subjects with good (n = 21) and poor (n = 18) sleep quality. We observed that the patients had the lowest CAR and sleep duration of all three groups and a higher latency to sleep than the healthy volunteers with a good sleep profile. Besides, low CAR was correlated with more severe depressive symptoms and worse sleep quality. There was no difference in serum BDNF levels between groups with distinct sleep quality. Taken together, our results showed a relationship between changes in CAR and in sleep quality in patients with treatment-resistant depression, which were correlated with the severity of disease, suggesting that cortisol could be a physiological link between sleep disturbance and major depression.

Chronic asthma-induced behavioral and hippocampal neuronal morphological changes are concurrent with BDNF, cofilin1 and Cdc42/RhoA alterations in immature mice

INTRODUCTION

Recent studies have found that persistent hypoxia caused by chronic asthma, especially during childhood, affects the development and function of the brain, but the mechanism is unclear. In the present study, BDNF and its signal pathway was investigated in mediating chronic asthma induced-neuronal changes that lead to behavior alterations.

METHODS

The chronic asthma model was induced by sensitization with ovalbumin for more than 9 weeks in immature mice. Morris water maze test (MWMT), open field test (OFT) and elevated plus maze test (EPMT) were used to conduct behavioral evaluation. Neuronal morphology in hippocampal CA1, CA3 and DG was assessed using ImageJ's Sholl plugin and RESCONSTRUCT software. BDNF signaling pathway related molecules was determined by Western blotting.

RESULTS

Chronic asthma does affect the behavioral performances of immature mice evaluated in MWMT, OFT, and EPMT. The analysis by three-dimensional reconstruction software found that following the behavioral alteration of asthmatic mice, dendritic changes also occurred in hippocampal neurons, including shortened dendrite length, significantly reduced number of dendritic branches, decreased density of dendritic spines, and reduced percentage of functional dendritic spine types. At the same time, by immunofluorescence and western blotting, we also found that alterations in dendritic morphology were consistent with activation of cofilin1 and changes in BDNF-Cdc42/RhoA levels. Some of the changes mentioned above can be alleviated by intranasal administration of budesonide.

CONCLUSION

Our data suggest that response similar to nicotine withdrawal or/and hypoxia induced by childhood chronic asthma enhances the BDNF-Cdc42/RhoA signaling pathway and activates cofilin1, leading to the remodeling of actin, causing the loss of dendritic spines and atrophy of dendrites, eventually resulting in behavioral alterations.

Serum brain-derived neurotrophic factor (BDNF) in sleep-disordered patients: relation to sleep stage N3 and rapid eye movement (REM) sleep across diagnostic entities

Experimental and clinical evidence suggests an association between neuroplasticity, brain-derived neurotrophic factor and sleep. We aimed at testing the hypotheses that brain-derived neurotrophic factor is associated with specific aspects of sleep architecture or sleep stages in patients with sleep disorders. We included 35 patients with primary insomnia, 31 patients with restless legs syndrome, 17 patients with idiopathic hypersomnia, 10 patients with narcolepsy and 37 healthy controls. Morning serum brain-derived neurotrophic factor concentrations were measured in patients and controls. In patients, blood sampling was followed by polysomnographic sleep investigation. Low brain-derived neurotrophic factor levels were associated with a low percentage of sleep stage N3 and rapid eye movement sleep across diagnostic entities. However, there was no difference in brain-derived neurotrophic factor levels between diagnostic groups. Our data indicate that serum levels of brain-derived neurotrophic factor, independent of a specific sleep disorder, are related to the proportion of sleep stage N3 and REM sleep. This preliminary observation is in accordance with the assumption that sleep stage N3 is involved in the regulation of neuroplasticity.

Changes in serum NGF levels after the exercise load in dogs: a pilot study

Serum nerve growth factor (NGF) levels are increased by the external stress in mice, humans and horses; however, similar variations have been unclear in dogs. Since dogs are usually subjected to conditions of work, exercise and activity as important partners of humans, we measured serum NGF levels post-exercise and compared them with serum cortisol levels, as a biomarker of physical stress. Serum cortisol levels were immediately elevated post-exercise and returned to basal levels within 1 hr. On the other hand, serum NGF levels were significantly increased 1 hr post-exercise and gradually returned to basal levels. Further research is necessary; nevertheless, we have demonstrated for the first time that serum NGF levels respond to exercise stress in dogs.

Could BDNF be involved in compensatory mechanisms to maintain cognitive performance despite acute sleep deprivation? An exploratory study

BACKGROUND

Neuroimaging studies suggest that acute sleep deprivation can lead to adaptations, such as compensatory recruitment of cerebral structures, to maintain cognitive performance despite sleep loss. However, the understanding of the neurochemical alterations related to these adaptations remains incomplete.

OBJECTIVE

Investigate BDNF levels, cognitive performance and their relations in healthy subjects after acute sleep deprivation.

METHODS

Nineteen sleep deprived (22.11±3.21years) and twenty control (25.10±4.42years) subjects completed depression, anxiety and sleep quality questionnaires. Sleep deprived group spent a full night awake performing different playful activities to keep themselves from sleeping. Attention, response inhibition capacity and working memory (prefrontal cortex-dependent) were assessed with Stroop and Digit Span tests. Declarative memory (hippocampus-dependent) was assessed with Logical Memory test. Serum BDNF was measured by sandwich ELISA. Data were analyzed with independent samples T-test, ANOVA, ANCOVA and curve estimation regressions. p<0.05 was deemed statistically significant.

RESULTS

The sleep deprived group showed higher BDNF levels and normal performance on attention, response inhibition capacity and working memory. However, declarative memory was impaired. A sigmoidal relation between BDNF and Stroop Test scores was found.

CONCLUSIONS

Increased BDNF could be related, at least in part, to the maintenance of normal prefrontal cognitive functions after sleep deprivation. This potential relation should be further investigated.

7,8-Dihydroxyflavone reduces sleep during dark phase and suppresses orexin A but not orexin B in mice

Brain-derived neurotrophic factor (BDNF) binds to Tropomyosin-receptor-kinase B (TrkB) receptors that regulate synaptic strength and plasticity in the mammalian nervous system. 7,8-Dihydroxyflavone (DHF) is a recently identified small molecule Trk B agonist that has been reported to ameliorate depression, attenuate the fear response, improve memory consolidation, and exert neuroprotective effects. Poor and disturbed sleep remains a symptom of major depressive disorder and most current antidepressants affect sleep. Therefore, we conducted sleep/wake recordings and concomitant measurement of brain orexins, endogenous peptides that suppress sleep, in mice for this study. Baseline polysomnograph recording was performed for 24 h followed by treatment with either 5 mg/kg of DHF or vehicle at the beginning of the dark phase. Animals were sacrificed the following day, one hour after the final treatment with DHF. Orexin A and B were quantified using ELISA and radioimmunoassay, respectively. Total sleep was significantly decreased in the DHF group, 4 h after drug administration in the dark phase, when compared with vehicle-treated animals. This difference was due to a significant decrease of non-rapid eye movement sleep, but not rapid eye movement sleep. DHF increased power of alpha and sigma bands but suppressed power of gamma band during sleep in dark phase. Interestingly, hypothalamic levels of orexin A were also significantly decreased in the DHF group (97 pg/mg) when compared with the vehicle-treated group (132 pg/mg). However, no significant differences of orexin B were observed between groups. Additionally, no change was found in immobility tests.

miRNA profiles in plasma from patients with sleep disorders reveal dysregulation of miRNAs in narcolepsy and other central hypersomnias

STUDY OBJECTIVES

MicroRNAs (miRNAs) have been implicated in the pathogenesis of human diseases including neurological disorders. The aim is to address the involvement of miRNAs in the pathophysiology of central hypersomnias including autoimmune narcolepsy with cataplexy and hypocretin deficiency (type 1 narcolepsy), narcolepsy without cataplexy (type 2 narcolepsy), and idiopathic hypersomnia.

DESIGN

We conducted high-throughput analysis of miRNA in plasma from three groups of patients-with type 1 narcolepsy, type 2 narcolepsy, and idiopathic hypersomnia, respectively-in comparison with healthy controls using quantitative real-time polymerase chain reaction (qPCR) panels.

SETTING

University hospital based sleep clinic and research laboratories.

PATIENTS

Twelve patients with type 1 narcolepsy, 12 patients with type 2 narcolepsy, 12 patients with idiopathic hypersomnia, and 12 healthy controls.

MEASUREMENTS AND RESULTS

By analyzing miRNA in plasma with qPCR we identified 50, 24, and 6 miRNAs that were different in patients with type 1 narcolepsy, type 2 narcolepsy, and idiopathic hypersomnia, respectively, compared with healthy controls. Twenty miRNA candidates who fulfilled the criteria of at least two-fold difference and p-value < 0.05 were selected to validate the miRNA changes in an independent cohort of patients. Four miRNAs differed significantly between type 1 narcolepsy patients and healthy controls. Levels of miR-30c, let-7f, and miR-26a were higher, whereas the level of miR-130a was lower in type 1 narcolepsy than healthy controls. The miRNA differences were not specific for type 1 narcolepsy, since the levels of the four miRNAs were also altered in patients with type 2 narcolepsy and idiopathic hypersomnia compared with healthy controls.

CONCLUSION

The levels of four miRNAs differed in plasma from patients with type 1 narcolepsy, type 2 narcolepsy and idiopathic hypersomnia suggesting that alterations of miRNAs may be involved in the pathophysiology of central hypersomnias.

Increased cerebrospinal fluid levels of nerve cell biomarkers in narcolepsy with cataplexy

BACKGROUND

The association between narcolepsy with cataplexy and the hypocretinergic system in the central nervous system is strong since up to 75-90% of all patients have cerebrospinal fluid (CSF) hypocretin-1 deficiency. The predominant occurrence of HLADQB1*0602 tissue type in narcolepsy patients and recent results from genome-wide association studies suggest an underlying immunological mechanism. The present study was initiated to clarify whether measurement of nerve cell biomarkers in CSF could give additional knowledge of the pathophysiological mechanisms causing narcolepsy with cataplexy.

METHODS

Two patient groups with narcolepsy, comprising 18 patients with low CSF hypocretin-1 concentrations and typical cataplexy, and 18 patients with normal CSF hypocretin-1 levels and mild cataplexy-like symptoms, were compared to 17 controls. We measured the nerve cell biomarkers beta-amyloid (Aβ42), total tau protein (T-tau), phosphorylated tau (P-tau) and neuron-specific enolase (NSE) in CSF.

RESULTS

The concentrations of all biomarkers were significantly elevated in both patient groups compared to the controls. The concentration of beta-amyloid was significantly higher in the patient group with normal CSF hypocretin-1 concentration than in those with low concentrations, whereas the other biomarkers showed no difference between the patient groups.

CONCLUSION

The findings of elevated levels of CSF biomarkers independent of CSF hypocretin-1 reduction may reflect alterations in cell metabolism. The results suggest a more extensive affection of the sleep regulating cellular network, affecting other neuronal sites important in the regulation of sleep, in addition to the hypocretin-producing neurons.