Gene expression profile of empirically delineated classes of unexplained chronic fatigue

OBJECTIVES: To identify the underlying gene expression profiles of unexplained chronic fatigue subjects classified into five or six class solutions by principal component (PCA) and latent class analyses (LCA). METHODS: Microarray expression data were available for 15,315 genes and 111 female subjects enrolled from a population-based study on chronic fatigue syndrome. Algorithms were developed to assign gene scores and threshold values that signified the contribution of each gene to discriminate the multiclasses in each LCA solution. Unsupervised dimensionality reduction was first used to remove noise or otherwise uninformative gene combinations, followed by supervised dimensionality reduction to isolate gene combinations that best separate the classes. RESULTS: The authors' gene score and threshold algorithms identified 32 and 26 genes capable of discriminating the five and six multiclass solutions, respectively. Pair-wise comparisons suggested that some genes (zinc finger protein 350 [ZNF350], solute carrier family 1, member 6 [SLC1A6], F-box protein 7 [FBX07] and vacuole 14 protein homolog [VAC14]) distinguished most classes of fatigued subjects from healthy subjects, whereas others (patched homolog 2 [PTCH2] and T-cell leukemia/lymphoma [TCL1A]) differentiated specific fatigue classes. CONCLUSION: A computational approach was developed for general use to identify discriminatory genes in any multiclass problem. Using this approach, differences in gene expression were found to discriminate some classes of unexplained chronic fatigue, particularly one termed interoception.     

Association of HPA axis genes with suicidal behaviour in schizophrenia

Family, adoption and twin studies show that genetics influences suicidal behaviour, but do not indicate specific susceptibility variants. Stress response is thought to be mediated by the corticotrophin-releasing hormone (CRH), which is known to be a regulator of the hypothalamic-pituitary-adrenal pathway (HPA). Alterations in HPA system have been related to impulsivity, aggression and suicidal behaviour, common feature in schizophrenia. CRH is the hypothalamic factor that stimulates the pituitary gland. To search for markers conferring genetic susceptibility to suicide, we typed six HPA axis genes (CRH, CRHR1, CRHR2, CRHBP, MC2R, NC3R1) in a cohort of 231 subjects with schizophrenia in which 81 attempted suicide. The genotype analyses yielded significant association between CRH binding protein (CRHBP) and suicide attempt (P = 0.035). The genotype analysis for quantitative measures of suicidal behaviour showed no association. The interaction analysis showed a significant interaction between CRH receptor type 1 (CRHR1) and CRH binding protein (CRHBP) in influencing suicide attempt and the severity of suicidal behaviour. Current results show that genetic variation in HPA axis genes could be associated with suicidal behaviour in schizophrenia. This is to our knowledge the first study on suicidal behaviour investigating the interaction among the HPA axis genes.     

An empirical delineation of the heterogeneity of chronic unexplained fatigue in women

OBJECTIVES: To test the hypothesis that medically unexplained chronic fatigue and chronic fatigue syndrome (CFS) are heterogeneous conditions, and to define the different conditions using both symptom and laboratory data. METHODS: We studied 159 women from KS, USA. A total of 51 of these suffered from fatigue consistent with established criteria for CFS, 55 had chronic fatigue of insufficient symptoms/severity for a CFS diagnosis and 53 were healthy controls matched by age and body mass index (BMI) against those with CFS. We used principal components analyses to define factors that best described the variable space and to reduce the number of variables. The 38 most explanatory variables were then used in latent class analyses to define discrete subject groups. RESULTS: Principal components analyses defined six discrete factors that explained 40% of the variance. Latent class analyses provided several interpretable solutions with four, five and six classes. The four-class solution was statistically most convincing, but the six-class solution was more interpretable. Class 1 defined 41 (26%) subjects with obesity and relative sleep hypnoea. Class 2 were 38 (24%) healthy subjects. Class 3 captured 24 (15%) obese relatively hypnoeic subjects, but with low heart rate variability and cortisol. Class 4 were 23 (14%) sleep-disturbed and myalgic subjects without obesity or significant depression. The two remaining classes with 22 (14%) and 11 (7%) subjects consisted of the most symptomatic and depressed, but without obesity or hypnoea. Class 5 had normal sleep indices. Class 6 was characterized by disturbed sleep, with low sleep heart rate variability, cortisol, and sex hormones. CONCLUSION: Chronic medically unexplained fatigue is heterogeneous. The putative syndromes were differentiated by obesity, sleep hypnoea, depression, physiological stress response, sleep disturbance, interoception and menopausal status. If these syndromes are externally validated and replicated, they may prove useful in determining the causes, pathophysiology and treatments of CFS.     

社会人群慢性疲劳心理影响因素研究

目的分析慢性疲劳的心理影响因素,为慢性疲劳预防策略的提出提供依据。方法采用Goldberg编制,一般健康问卷(GHQ-20)进行调查。数据录入采用Epidata3.0,经核对无误后转入SPSS11.5进行统计分析。主要应用χ2检验、t检验、非条件Logistic回归分析。结果太原市人群慢性疲劳人口学分布特征:排除有疾病患者121人,981人中非慢性疲劳(非CF)占77.1%(756人),慢性疲劳(CF)占22.9%(225人)。不同文化程度慢性疲劳患病率不同(χ2=13.550,P=0.009)。慢性疲劳与心理影响因素:单因素分析显示忧郁(t=2.939,P=0.004)、抑郁(t=3.434,P=0.001)是慢性疲劳的危险因素,自我肯定(t=-7.367,P=0.000)是慢性疲劳的保护因素。多因素分析表明,高文化程度(OR=1.508)是慢性疲劳的危险因素,自我肯定(OR=0.752)是慢性疲劳的保护因素。结论心理自我肯定水平与慢性疲劳的发生密切相关。     

Influence of chronic stress on brain corticosteroid receptors and HPA axis activity

BackgroundDisruption of the glucocorticoid negative feedback system evoked in animals by chronic stress can be induced by downregulation of glucocorticoid receptors (GRs) in several brain regions. In the present study, the dynamics of the changes in GRs, in brain structures involved in stress reactions, prefrontal cortex, hippocampus and hypothalamus was compared with the peripheral hypothalamo-pituitary-adrenocortical (HPA) axis hormones response to chronic stress.MethodsRats were exposed to 10 min restraint or restrained twice a day for 3, 7 or 14 days, and 24 h after the last stress session exposed to homotypic stress for 10 min. Control rats were not restrained. After rapid decapitation at 0, 1, 2, and 3 h after stress termination, trunk blood for plasma adrenocorticotropic hormone (ACTH) and corticosterone determinations was collected and prefrontal cortex, hippocampus and hypothalamus were excised and frozen. Plasma hormones were determined using commercially available kits and glucocorticoids and mineralocorticoids protein levels in brain structure samples were determined by western blot procedure.ResultsRestraint stress alone significantly decreased glucocorticoid receptor (GR) level in prefrontal cortex and hippocampus, and increased mineralocorticoid receptor (MR) level in hypothalamus. Prior repeated stress for 3 days significantly increased GR protein level in hippocampus and diminished that level in hypothalamus in 7 days stressed rats. Acute stress-induced strong increase in plasma ACTH and corticosterone levels decreased to control level after 1 or 2 h, respectively. Prior repeated stress for 3 days markedly diminished the fall in plasma ACTH level and repeated stress for 7 days moderately deepened this decrease. Plasma ACTH level induced by homotypic stress in rats exposed to restraint for 3, 7, and 14 days did not markedly differ from its control level, whereas plasma corticosterone response was significantly diminished. The fast decrease of stress-induced high plasma ACTH and corticosterone levels was accompanied by a parallel decline of GR level only in prefrontal cortex but not in the hippocampus or hypothalamus.ConclusionsComparison of the dynamics of changes in plasma ACTH and corticosterone level with respective alterations in GR and MR in brain structures suggests that the buffering effect of repeated stress depends on the period of habituation to stress and the brain structure involved in regulation of these stress response.     

The validity of an empirical delineation of heterogeneity in chronic unexplained fatigue

OBJECTIVES: To validate a latent class structure derived empirically from a clinical data set obtained from persons with chronic medically unexplained fatigue. METHODS: The strategies utilized in this validation study included: recalculating latent class analysis (LCA) results varying random seeds and the number of initial random starting sets; recalculating LCA results by substituting alternate variables to demonstrate a robust solution; determining the statistical significance of between-class differences on disability, fatigue and demographic measures omitted from the data set used for LCA; cross-classifying class membership using established Centers for Disease Control and Prevention (CDC) research criteria for chronic fatigue syndrome (CFS) to compare the relative proportions of subjects designated CFS, chronic fatigue (not CFS) or healthy controls captured by the latent classes. RESULTS: Recalculation of results and substitution of variables for low-loading variables demonstrated a robust LCA result. Highly significant between-class differences were confirmed between Class 2 (well) and those interpreted as ill/fatigued. Analysis of between-class differences for the fatigue groups revealed significant differences for all disability and fatigue variables, but with equivalent levels of reported activity and reduction in motivation. Cross-classification against established CDC criteria demonstrated that 89% of subjects constituting Class 2 (well) were indeed nonfatigued controls. A general tendency for grouping CFS cases in the multiple symptomatic classes was noted. CONCLUSION: This study established reasonably good validity for an empirically-derived latent class solution reflecting considerable heterogeneity among subjects with medically unexplained chronic fatigue. This work strengthens the growing understanding of CFS as a heterogeneous entity comprised of several conditions with different underlying pathophysiological mechanisms.     

Effect of repeated restraint on homotypic stress-induced nitric oxide synthases expression in brain structures regulating HPA axis

BackgroundRestraint stress (RS) markedly increases interleukin 1-β (IL-1β) generation in brain structures involved in hypothalamic-pituitary adrenocortical (HPA) axis regulation. The IL-1β-induced transient stimulation of HPA axis activity was parallel in time and magnitude to respective changes in regulation of HPA activity. In the present experiment the expression of neuron al and inducible nitric oxide synthase (nNOS and iNOS) were investigated in prefrontal cortex, hippocampus and hypothalamus in response to acute restraint stress in control and prior repeatedly restrained rats.MethodsExperiments were performed on male Wistar rats which were exposed to 10 min restraint stress or restrained twice a day for 3 days, and 24 h after the last stress period exposed to homotypic stress for 10 min. After rapid decapitation at 0,1,2 and 3 h after cessation of stress, trunk blood was collected and prefrontal cortex, hippocampus and hypothalamus were excised and frozen. Interleukin-1β, adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels were determined in plasma using commercially available kits and neuronal nitric oxide synthase (nNOS) and inducible nitric oxide synthase (iNOS) in brain structure samples were analyzed by western blot procedure.ResultsPrior repeated restraint stress enhanced the acute restraint stress induced increase in IL-1β levels in all three structures examined. Restraint stress for 10 min moderately decreased nNOS level in prefrontal cortex in control rats, augmented this level in hippocampus and markedly increased nNOS level in hypothalamus. Restraint itself significantly decreased iNOS level in prefrontal cortex, while it enhanced iNOS level in hippocampus and hypothalamus. Prior restraint stress for 3 days enhanced the nNOS level in prefrontal cortex and hippocampus and did not substantially affect nNOS levels response in hypothalamus. Repeated restraint stress considerably augmented the iNOS levels in both prefrontal cortex, hippocampus and hypothalamus induced by followed homotypic stress.ConclusionThese results indicate that during restraint stress nNOS regulate formation of low amount of NO and the high-output generation of NO is effected by inducible isoform of nitric oxide synthase. Prior repeated stress significantly enhances the homotypic stress-induced nNOS and iNOS responses.     

Exploration of the gene expression correlates of chronic unexplained fatigue using factor analysis

OBJECTIVE: To identify biomarkers of chronic fatigue syndrome (CFS) and related disorders through analysis of microarray data, pathology test results and self-report symptom profiles. METHOD: To empirically derive the symptom domains of the illnesses, factor analysis was performed on responses to self-report questionnaires (multidimensional fatigue inventory, Centers for Disease Control and Prevention (CDC) symptom inventory and Zung depression scale) before validation with independent datasets. Gene expression patterns that distinguished subjects across each factor dimension were then sought. RESULTS: A four-factor solution was favored, featuring 'fatigue' and 'mood disturbance' factors. Scores on these factors correlated with measures of disability on the Short Form (SF)-36. A total of 57 genes that distinguished subjects along each factor dimension were identified, although the separation was significant only for subjects beyond the extreme (15th and 85th) percentiles of severity. Clustering of laboratory parameters with expression of these genes revealed associations with serum measurements of pH, electrolytes, glucose, urea, creatinine, and liver enzymes (aspartate amino transferase [AST] and alanine amino transferase [AST]); as well as hematocrit and white cell count. CONCLUSION: CFS is a complex syndrome that cannot simply be associated with changes in individual laboratory tests or expression levels of individual genes. No clear association with gene expression and individual symptom domains was found. However, analysis of such multifacetted datasets is likely to be an important means to elucidate the pathogenesis of CFS.     

Allopregnanolone modulation of HPA axis function in the adult rat

Rationale

GABAergic neuronal circuits regulate neuroendocrine stress response, and the most potent positive endogenous modulator of GABA_A receptor function is allopregnanolone. This neurosteroid acts in a nongenomic manner to selectively increase the inhibitory signal meditated by GABA_A receptors; in addition, it also induces long-lasting changes in the expression of specific GABA_A receptor subunits in various brain regions, with consequent changes in receptor function.

Objective

The objective of this review is to summarize our findings on emotional state and stress responsiveness in three animal models in which basal brain concentrations of allopregnanolone differ. It is postulated that individual differences in allopregnanolone levels can influence general resilience.

Results

The results showed that there is an apparent correlation between endogenous levels of brain allopregnanolone and basal and stress-stimulated HPA axis activity.

Conclusion

The relationship between endogenous brain levels of allopregnanolone and HPA axis activity and function sustains the therapeutic potential of this neurosteroid for the treatment of stress-associated disorders.     

Interactions of chronic lead exposure and intermittent stress: consequences for brain catecholamine systems and associated behaviors and HPA axis function.

Elevated lead (Pb) burden and high stress levels are co-occurring risk factors in low socioeconomic status (SES) children. Our previous work demonstrated that maternal Pb exposure can permanently alter hypothalamic-pituitary-adrenal (HPA) axis function and responsivity to stress challenges in offspring. The current study sought to determine the consequences of chronic Pb exposures initiated later in development combined with variable intermittent stress challenges. Male rats were exposed chronically from weaning to 0, 50, or 150 ppm Pb acetate drinking solutions (producing blood Pb levels of <5, 9-15, and 23-27 mug/dl, respectively). Pb itself decreased basal plasma corticosterone, with greater effects at 50 than 150 ppm; 150 ppm reduced both cytosolic and nuclear glucocorticoid receptor binding. Responsivity to stress challenges including novelty, cold, and restraint, was measured as changes in Fixed Interval (FI) schedule-controlled behavior in a subset of rats within each group. FI performance was modified by novelty stress only in Pb-treated rats, whereas cold and restraint stress effects were comparable across groups. Novelty elevated corticosterone equivalently across groups, but cold stress markedly increased corticosterone only in Pb-treated groups. The pattern of Pb-induced changes in serotonin (5-HT) or its metabolite 5-HIAA in frontal cortex, nucleus accumbens, striatum, and hypothalamus resembled that observed for basal corticosterone levels indicating a relationship between these variables. In addition to suggesting the potential for HPA axis-mediated effects of Pb on the central nervous system, these findings also raise questions about whether single chemicals studied in isolation from other relevant risk factors can adequately identify neurotoxic hazards.     

Allostatic load is associated with symptoms in chronic fatigue syndrome patients

OBJECTIVES: To further explore the relationship between chronic fatigue syndrome (CFS) and allostatic load (AL), we conducted a computational analysis involving 43 patients with CFS and 60 nonfatigued, healthy controls (NF) enrolled in a population-based case-control study in Wichita (KS, USA). We used traditional biostatistical methods to measure the association of high AL to standardized measures of physical and mental functioning, disability, fatigue and general symptom severity. We also used nonlinear regression technology embedded in machine learning algorithms to learn equations predicting various CFS symptoms based on the individual components of the allostatic load index (ALI). METHODS: An ALI was computed for all study participants using available laboratory and clinical data on metabolic, cardiovascular and hypothalamic-pituitary-adrenal (HPA) axis factors. Physical and mental functioning/impairment was measured using the Medical Outcomes Study 36-item Short Form Health Survey (SF-36); current fatigue was measured using the 20-item multidimensional fatigue inventory (MFI); frequency and intensity of symptoms was measured using the 19-item symptom inventory (SI). Genetic programming, a nonlinear regression technique, was used to learn an ensemble of different predictive equations rather just than a single one. Statistical analysis was based on the calculation of the percentage of equations in the ensemble that utilized each input variable, producing a measure of the 'utility' of the variable for the predictive problem at hand. Traditional biostatistics methods include the median and Wilcoxon tests for comparing the median levels of subscale scores obtained on the SF-36, the MFI and the SI summary score. RESULTS: Among CFS patients, but not controls, a high level of AL was significantly associated with lower median values (indicating worse health) of bodily pain, physical functioning and general symptom frequency/intensity. Using genetic programming, the ALI was determined to be a better predictor of these three health measures than any subcombination of ALI components among cases, but not controls.     

Polymorphisms of genes in nitric oxide-forming pathway associated with ischemic stroke in Chinese Han population

Aim:

To investigate the association of polymorphisms in four critical genes implicated in the NO-forming pathway with ischemic stroke (IS) in a Chinese Han population.

Methods:

DNA samples of 558 IS patients and 557 healthy controls from Chinese Han population were genotyped using the Taqman^TM 7900HT Sequence Detection System. Six SNPs (rs841, rs1049255, rs2297518, rs1799983, rs2020744, rs4673) of the 4 related genes (eNOS, iNOS, GCH1, and CYBA) in the NO forming pathway were analyzed using the SPSS 13.0 software package for Windows.

Results:

One SNP located in the intron of GCH1 (rs841) was associated with IS independent of the traditional cardiovascular risk factors in co-dominant and dominant models (P=0.003, q=0.027; P=0.00006, q=0.0108; respectively). Moreover, the combination of rs1049255 CC+CT and rs841 GA+AA genotypes was associated with significantly higher risk for IS after adjustments (OR=1.73, 95% CI: 1.27–2.35, P<0.0001, q<0.0001).

Conclusion:

The data suggest that genetic variants within the NO-forming pathway alter susceptibility to IS in Chinese Han population. Replication of the present results in other independent cohorts is warranted.     

Basal activity of the HPA axis and cognitive function in anorexia nervosa

Elevated cortisol and cognitive impairments have been described in anorexia nervosa, but the relationship between these two variables has not been adequately explored. We profiled the pattern and extent of the cognitive impairment in anorexia nervosa and determined how this related to cortisol secretion. Twenty patients with anorexia nervosa and a matched control group completed a computerized cognitive assessment battery. Diurnal cortisol secretion was measured by serial saliva sampling. Patients were significantly impaired on tasks of attention, long-term memory and working memory. Both groups showed the expected diurnal variation in cortisol production, but no evidence was found for patient cortisol hypersecretion. No correlation was found between cortisol secretion and any of the cognitive task measures. These data suggest that at least some of the cognitive impairments seen in anorexia nervosa are attributable to something other than a basal increase in cortisol secretion. The limitations of cortisol as an indicator of HPA axis activity are discussed.     

HPA轴功能紊乱干预药物的研究进展

目的对近年来基于下丘脑-垂体-肾上腺（hypothalamic-pituitary-adrenal ,HPA）轴功能调节治疗2型糖尿病和其他代谢疾病的药物做以综述,为H PA轴功能紊乱引起的相关疾病的治疗提供理论参考。方法查阅国内外文献,分析、总结 H PA轴功能紊乱干预药物的研究现状和研究前景。结果 HPA轴功能紊乱,尤其是 HPA轴功能亢进在2型糖尿病、抑郁症等疾病的发病过程中发挥重要作用;目前有以下几类通过作用于HPA轴不同靶点调节HPA轴功能的药物,即11β-HSD1抑制剂、糖皮质激素受体拮抗剂、多巴胺受体拮抗剂和选择性5-H T再摄取抑制剂等,具体机制还有待进一步阐明。结论通过调节H PA轴活性有可能达到预防和治疗2型糖尿病及其他相关疾病的目的。     

Effects of acute and chronic administration of mu- and delta-opioid agonists on the hypothalamic-pituitary-adrenocortical (HPA) axis in the rat.

The control of hypothalamic-pituitary-adrenocortical (HPA) activity by opioids seems to involve stimulatory and inhibitory pathways. The purpose of the present study was to determine the acute and chronic effects of selective mu- and delta-opioid agonists, administered centrally (i.c.v.) on pituitary-adrenocortical activity in the rat. The mu-agonist DAGO ([D-Ala2,N-MePhe4,Gly-ol5]enkephalin; 0.75 nmol i.c.v.) and the delta-agonist DPDPE ([D-Pen2,5]enkephalin; 194 nmol i.c.v.) both stimulated corticosterone release when administered acutely. Chronic administration of DAGO and DPDPE resulted in the development of tolerance to their neuroendocrine effects. These data suggest that both mu- and delta-opioid receptors are involved in the regulation of HPA activity under physiological conditions and during opiate abuse.     

Flavonoids of St. John's Wort reduce HPA axis function in the rat

A common biological alteration in patients with major depression is the activation of the hypothalamic-pituitary-adrenal (HPA) axis, manifested as hypersecretion of adrenocorticotropic hormone (ACTH) and cortisol. The hyperactivity of the HPA axis in depressed patients can be corrected during clinically effective therapy with standard antidepressant drugs such as imipramine, indicating that the HPA axis may be an important target for antidepressant action. We previously showed that a methanolic extract of St. John's Wort (SJW) and hypericin, one of its active constituents, both have delayed effects on the expression of genes that are involved in the regulation of the hypothalamic-pituitary-adrenal (HPA) axis , whereas the phloroglucinol derivative hyperforin was inactive in the same model . Since flavonoids of SJW are also discussed as active constituents it was of interest to determine whether these compounds can modulate HPA axis function. Imipramine (15 mg/kg), hypericin (0.2 mg/kg), hyperoside (0.6 mg/kg), isoquercitrin (0.6 mg/kg) and miquelianin (0.6 mg/kg) given daily by gavage for two weeks significantly down-regulated circulating plasma levels of ACTH and corticosterone by 40 - 70 %. However, none of the compounds tested had an effect on plasma ACTH and corticosterone levels after chronic treatment (daily gavage for 8 weeks). Our data suggest that besides hypericin, flavonoids of SJW play an important role in the modulation of HPA axis function. Furthermore, the results support the hypothesis that flavonoids are involved in the antidepressant effects of SJW.     

百合皂苷对抑郁模型大鼠HPA轴的影响

抑郁症被称为精神疾病的"心灵感冒",其患病率预计到2020年将跃升到第2位[1].下丘脑-垂体-肾上腺轴(hypothalamic pituitary adrenal axis, HPA轴)在抑郁的发病机制中发挥着重要的作用.