Tag: Chrousos

Chronic Fatigue Syndrome

Excerpt:

Fatigue is a universal symptom, occurring in all individuals after prolonged exertion or lack of sleep. However, when fatigue is persistently present, without adequate environmental or medical explanation, fatigue has been recognised as the hallmark of a frequent and enigmatic clinical syndrome. Although difficult to precisely define and measure, fatigue is a pervasive sense of tiredness or lack of energy, that is not related exclusively to exertion. Fatigue may be appreciated centrally in terms of concentration, memory and motivation, or appreciated peripherally, where symptoms are often referred to the muscles. Chronic Fatigue Syndrome (CFS) is a term that was chosen and defined by Holmes et al., in 1988 to describe a combination of non-specific symptoms including profound fatigue, weakness, malaise and cognitive impairment with a remarkable lack of objective physical or laboratory abnormalities (1).

This syndrome had previously been known as “Chronic Epstein-Barr Virus Syndrome” and “Chronic Mononucleosis”. The terminology “CFS” was widely accepted because it implies no aetiology or specific pathological process. Several definitions of CFS have been developed, primarily to standardise research (2,3). It was not intended that they be used for clinical diagnosis. The Canadian Clinical Working Case Definition of Chronic Fatigue Syndrome was developed in response to an increasing need for such a definition for practising clinicians (4). It is the first definition that was created primarily to aid in clinical diagnosis, by encompassing many of the positive signs and symptoms of CFS, in order that it can be recognised as a distinct entity and distinguished from other clinical syndromes that have overlapping symptoms.

Copyright © 2000-2017, MDText.com, Inc.

 

Source: Torpy BDJ, Saranapala M. Chronic Fatigue Syndrome. In: De Groot LJ, Chrousos G, Dungan K, Feingold KR, Grossman A, Hershman JM, Koch C, Korbonits M, McLachlan R, New M, Purnell J, Rebar R,Singer F, Vinik A, editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. 2014 Nov 20. https://www.ncbi.nlm.nih.gov/books/NBK279099/ (Full article)

 

Chronic fatigue syndrome: what role does the autonomic nervous system play in the pathophysiology of this complex illness?

Abstract:

Chronic fatigue syndrome (CFS) is a serious health concern affecting over 800000 Americans of all ages, races and socioeconomic groups and both genders. The etiology and pathophysiology of CFS are unknown, yet studies have suggested an involvement of the autonomic nervous system (ANS). A symposium was organized in December 2000 to explore the possibility of an association between ANS dysfunction and CFS, with special emphasis on the interactions between ANS dysfunction and other abnormalities noted in the immune and endocrine systems of individuals with CFS. This paper represents the consensus of the panel of experts who participated in this meeting.

Copyright 2002 S. Karger AG, Basel

 

Source: Gerrity TR, Bates J, Bell DS, Chrousos G, Furst G, Hedrick T, Hurwitz B, Kula RW, Levine SM, Moore RC, Schondorf R. Chronic fatigue syndrome: what role does the autonomic nervous system play in the pathophysiology of this complex illness? Neuroimmunomodulation. 2002-2003;10(3):134-41. http://www.ncbi.nlm.nih.gov/pubmed/12481153

 

The sympathetic nerve–an integrative interface between two supersystems: the brain and the immune system

Abstract:

The brain and the immune system are the two major adaptive systems of the body. During an immune response the brain and the immune system “talk to each other” and this process is essential for maintaining homeostasis. Two major pathway systems are involved in this cross-talk: the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS). This overview focuses on the role of SNS in neuroimmune interactions, an area that has received much less attention than the role of HPA axis.

Evidence accumulated over the last 20 years suggests that norepinephrine (NE) fulfills the criteria for neurotransmitter/neuromodulator in lymphoid organs. Thus, primary and secondary lymphoid organs receive extensive sympathetic/noradrenergic innervation. Under stimulation, NE is released from the sympathetic nerve terminals in these organs, and the target immune cells express adrenoreceptors.

Through stimulation of these receptors, locally released NE, or circulating catecholamines such as epinephrine, affect lymphocyte traffic, circulation, and proliferation, and modulate cytokine production and the functional activity of different lymphoid cells. Although there exists substantial sympathetic innervation in the bone marrow, and particularly in the thymus and mucosal tissues, our knowledge about the effect of the sympathetic neural input on hematopoiesis, thymocyte development, and mucosal immunity is extremely modest.

In addition, recent evidence is discussed that NE and epinephrine, through stimulation of the beta(2)-adrenoreceptor-cAMP-protein kinase A pathway, inhibit the production of type 1/proinflammatory cytokines, such as interleukin (IL-12), tumor necrosis factor-alpha, and interferon-gamma by antigen-presenting cells and T helper (Th) 1 cells, whereas they stimulate the production of type 2/anti-inflammatory cytokines such as IL-10 and transforming growth factor-beta.

Through this mechanism, systemically, endogenous catecholamines may cause a selective suppression of Th1 responses and cellular immunity, and a Th2 shift toward dominance of humoral immunity. On the other hand, in certain local responses, and under certain conditions, catecholamines may actually boost regional immune responses, through induction of IL-1, tumor necrosis factor-alpha, and primarily IL-8 production.

Thus, the activation of SNS during an immune response might be aimed to localize the inflammatory response, through induction of neutrophil accumulation and stimulation of more specific humoral immune responses, although systemically it may suppress Th1 responses, and, thus protect the organism from the detrimental effects of proinflammatory cytokines and other products of activated macrophages.

The above-mentioned immunomodulatory effects of catecholamines and the role of SNS are also discussed in the context of their clinical implication in certain infections, major injury and sepsis, autoimmunity, chronic pain and fatigue syndromes, and tumor growth.

Finally, the pharmacological manipulation of the sympathetic-immune interface is reviewed with focus on new therapeutic strategies using selective alpha(2)- and beta(2)-adrenoreceptor agonists and antagonists and inhibitors of phosphodiesterase type IV in the treatment of experimental models of autoimmune diseases, fibromyalgia, and chronic fatigue syndrome.

 

Source: Elenkov IJ, Wilder RL, Chrousos GP, Vizi ES. The sympathetic nerve–an integrative interface between two supersystems: the brain and the immune system. Pharmacol Rev. 2000 Dec;52(4):595-638. http://pharmrev.aspetjournals.org/content/52/4/595.long (Full article)

 

Self-reported sensitivity to chemical exposures in five clinical populations and healthy controls

Abstract:

Two hundred and twenty-five subjects, including normal volunteers and patients with previously documented seasonal affective disorder (SAD),chronic fatigue syndrome (CFS), Cushing’s syndrome, Addison’s disease and obsessive-compulsive disorder (OCD), completed a self-rated inventory of reported sensitivity to various chemical exposures.

Patients with CFS, Addison’s disease and SAD self-reported more sensitivity to chemical exposures than normal controls. In addition, women reported more sensitivity than men.

This report suggests that chemical sensitivity may be a relevant area to explore in certain medical and psychiatric populations. A possible relationship between reported chemical sensitivity and hypothalamic-pituitary-adrenal (HPA)-axis functioning is discussed.

 

Source: Nawab SS, Miller CS, Dale JK, Greenberg BD, Friedman TC, Chrousos GP, Straus SE, Rosenthal NE. Self-reported sensitivity to chemical exposures in five clinical populations and healthy controls. Psychiatry Res. 2000 Jul 24;95(1):67-74. http://www.ncbi.nlm.nih.gov/pubmed/10904124

 

Chronic pain and fatigue syndromes: overlapping clinical and neuroendocrine features and potential pathogenic mechanisms

Abstract:

Patients with unexplained chronic pain and/or fatigue have been described for centuries in the medical literature, although the terms used to describe these symptom complexes have changed frequently. The currently preferred terms for these syndromes are fibromyalgia and chronic fatigue syndrome, names which describe the prominent clinical features of the illness without any attempt to identify the cause.

This review delineates the definitions of these syndromes, and the overlapping clinical features. A hypothesis is presented to demonstrate how genetic and environmental factors may interact to cause the development of these syndromes, which we postulate are caused by central nervous system dysfunction. Various components of the central nervous system appear to be involved, including the hypothalamic pituitary axes, pain-processing pathways, and autonomic nervous system. These central nervous system changes lead to corresponding changes in immune function, which we postulate are epiphenomena rather than the cause of the illnesses.

 

Source: Clauw DJ, Chrousos GP. Chronic pain and fatigue syndromes: overlapping clinical and neuroendocrine features and potential pathogenic mechanisms. Neuroimmunomodulation. 1997 May-Jun;4(3):134-53. http://www.ncbi.nlm.nih.gov/pubmed/9500148

 

Corticotropin releasing hormone in the pathophysiology of melancholic and atypical depression and in the mechanism of action of antidepressant drugs

Abstract:

Hypercortisolism in depression seems to preferentially reflect activation of hypothalamic CRH secretion. Although it has been postulated that this hypercortisolism is an epiphenomenon of the pain and stress of major depression, our data showing preferential participation of AVP in the hypercortisolism of chronic inflammatory disease suggest specificity for the pathophysiology of hypercortisolism in depression.

Our findings that imipramine causes a down-regulation of the HPA axis in experimental animals and healthy controls support an intrinsic role for CRH in the pathophysiology of melancholia and in the mechanism of action of psychotropic agents. Our data suggest that hypercortisolism is not the only form of HPA dysregulation in major depression.

In a series of studies, commencing in patients with Cushing’s disease, and extending to hyperimmune fatigue states such as chronic fatigue syndrome and examples of atypical depression such as seasonal affective disorder, we have advanced data suggesting hypofunction of hypothalamic CRH neurons. These data raise the question that the hyperphagia, hypersomnia, and fatigue associated with syndromes of atypical depression could reflect a central deficiency of a potent arousal-producing anorexogenic neuropeptide.

In the light of data presented elsewhere in this symposium regarding the role of a hypofunctioning hypothalamic CRH neuron in susceptibility to inflammatory disease, these data also raise the question of a common pathophysiological mechanism in syndromes associated both with inflammatory manifestations and atypical depressive symptoms. This concept of hypofunctioning of hypothalamic CRH neurons in these disorders also raises the question of novel forms of neuropharmacological intervention in both inflammatory diseases and atypical depressive syndromes.

 

Source: Gold PW, Licinio J, Wong ML, Chrousos GP. Corticotropin releasing hormone in the pathophysiology of melancholic and atypical depression and in the mechanism of action of antidepressant drugs. Ann N Y Acad Sci. 1995 Dec 29;771:716-29. http://www.ncbi.nlm.nih.gov/pubmed/8597444

 

Evidence for impaired activation of the hypothalamic-pituitary-adrenal axis in patients with chronic fatigue syndrome

Abstract:

Chronic fatigue syndrome is characterized by persistent or relapsing debilitating fatigue for at least 6 months in the absence of a medical diagnosis that would explain the clinical presentation. Because primary glucocorticoid deficiency states and affective disorders putatively associated with a deficiency of the arousal-producing neuropeptide CRH can be associated with similar symptoms, we report here a study of the functional integrity of the various components of the hypothalamic-pituitary-adrenal axis in patients meeting research case criteria for chronic fatigue syndrome.

Thirty patients and 72 normal volunteers were studied. Basal activity of the hypothalamic-pituitary-adrenal axis was estimated by determinations of 24-h urinary free cortisol-excretion, evening basal plasma total and free cortisol concentrations, and the cortisol binding globulin-binding capacity. The adrenal cortex was evaluated indirectly by cortisol responses during ovine CRH (oCRH) stimulation testing and directly by cortisol responses to graded submaximal doses of ACTH. Plasma ACTH and cortisol responses to oCRH were employed as a direct measure of the functional integrity of the pituitary corticotroph cell. Central CRH secretion was assessed by measuring its level in cerebrospinal fluid.

Compared to normal subjects, patients demonstrated significantly reduced basal evening glucocorticoid levels (89.0 +/- 8.7 vs. 148.4 +/- 20.3 nmol/L; P less than 0.01) and low 24-h urinary free cortisol excretion (122.7 +/- 8.9 vs. 203.1 +/- 10.7 nmol/24 h; P less than 0.0002), but elevated basal evening ACTH concentrations.

There was increased adrenocortical sensitivity to ACTH, but a reduced maximal response [F(3.26, 65.16) = 5.50; P = 0.0015). Patients showed attenuated net integrated ACTH responses to oCRH (128.0 +/- 26.4 vs. 225.4 +/- 34.5 pmol/L.min, P less than 0.04). Cerebrospinal fluid CRH levels in patients were no different from control values (8.4 +/- 0.6 vs. 7.7 +/- 0.5 pmol/L; P = NS).

Although we cannot definitively account for the etiology of the mild glucocorticoid deficiency seen in chronic fatigue syndrome patients, the enhanced adrenocortical sensitivity to exogenous ACTH and blunted ACTH responses to oCRH are incompatible with a primary adrenal insufficiency. A pituitary source is also unlikely, since basal evening plasma ACTH concentrations were elevated.

Hence, the data are most compatible with a mild central adrenal insufficiency secondary to either a deficiency of CRH or some other central stimulus to the pituitary-adrenal axis. Whether a mild glucocorticoid deficiency or a putative deficiency of an arousal-producing neuropeptide such as CRH is related to the clinical symptomatology of the chronic fatigue syndrome remains to be determined.

 

Source: Demitrack MA, Dale JK, Straus SE, Laue L, Listwak SJ, Kruesi MJ, Chrousos GP, Gold PW. Evidence for impaired activation of the hypothalamic-pituitary-adrenal axis in patients with chronic fatigue syndrome. J Clin Endocrinol Metab. 1991 Dec;73(6):1224-34. http://www.ncbi.nlm.nih.gov/pubmed/1659582