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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The stress system coordinates the adaptive responses of the organism to stressors of any kind.(1). The main components of the stress system are the corticotropin-releasing hormone (CRH) and locus ceruleus-norepinephrine (LC/NE)-autonomic systems and their peripheral effectors, the pituitary-adrenal axis, and the limbs of the autonomic system. Activation of the stress system leads to behavioral and peripheral changes that improve the ability of the organism to adjust homeostasis and increase its chances for survival. The CRH and LC/NE systems stimulate arousal and attention, as well as the mesocorticolimbic dopaminergic system, which is involved in anticipatory and reward phenomena, and the hypothalamic beta-endorphin system, which suppresses pain sensation and, hence, increases analgesia. CRH inhibits appetite and activates thermogenesis via the catecholaminergic system. Also, reciprocal interactions exist between the amygdala and the hippocampus and the stress system, which stimulates these elements and is regulated by them. CRH plays an important role in inhibiting GnRH secretion during stress, while, via somatostatin, it also inhibits GH, TRH and TSH secretion, suppressing, thus, the reproductive, growth and thyroid functions. Interestingly, all three of these functions receive and depend on positive catecholaminergic input. The end-hormones of the hypothalamic-pituitary-adrenal (HPA) axis, glucocorticoids, on the other hand, have multiple roles. They simultaneously inhibit the CRH, LC/NE and beta-endorphin systems and stimulate the mesocorticolimbic dopaminergic system and the CRH peptidergic central nucleus of the amygdala. In addition, they directly inhibit pituitary gonadotropin, GH and TSH secretion, render the target tissues of sex steroids and growth factors resistant to these substances and suppress the 5' deiodinase, which converts the relatively inactive tetraiodothyronine (T(4)) to triiodothyronine (T(3)), contributing further to the suppression of reproductive, growth and thyroid functions. They also have direct as well as insulin-mediated effects on adipose tissue, ultimately promoting visceral adiposity, insulin resistance, dyslipidemia and hypertension (metabolic syndrome X) and direct effects on the bone, causing "low turnover" osteoporosis. Central CRH, via glucocorticoids and catecholamines, inhibits the inflammatory reaction, while directly secreted by peripheral nerves CRH stimulates local inflammation (immune CRH). CRH antagonists may be useful in human pathologic states, such as melancholic depression and chronic anxiety, associated with chronic hyperactivity of the stress system, along with predictable behavioral, neuroendocrine, metabolic and immune changes, based on the interrelations outlined above. Conversely, potentiators of CRH secretion/action may be useful to treat atypical depression, postpartum depression and the fibromyalgia/chronic fatigue syndromes, all characterized by low HPA axis and LC/NE activity, fatigue, depressive symptomatology, hyperalgesia and increased immune/inflammatory responses to stimuli.
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PMID:Hypothalamic-pituitary-adrenal axis, neuroendocrine factors and stress. 1237 95

Stress activates the central and peripheral components of the stress system, i.e., the hypothalamic-pituitary-adrenal (HPA) axis and the arousal/sympathetic system. The principal effectors of the stress system are corticotropin-releasing hormone (CRH), arginine vasopressin, the proopiomelanocortin-derived peptides alpha-melanocyte-stimulating hormone and beta-endorphin, the glucocorticoids, and the catecholamines norepinephrine and epinephrine. Appropriate responsiveness of the stress system to stressors is a crucial prerequisite for a sense of well-being, adequate performance of tasks and positive social interactions. By contrast, inappropriate responsiveness of the stress system may impair growth and development, and may account for a number of endocrine, metabolic, autoimmune and psychiatric disorders. The development and severity of these conditions primarily depend on the genetic vulnerability of the individual, the exposure to adverse environmental factors and the timing of the stressful event(s), given that prenatal life, infancy, childhood and adolescence are critical periods characterized by increased vulnerability to stressors. The developing brain undergoes rapid growth and is characterized by high turnover of neuronal connections during the prenatal and early postnatal life. These processes and, hence, brain plasticity, slow down during childhood and puberty, and plateau in young adulthood. Hormonal actions in early life, and to a much lesser extent later, can be organizational, i.e., can have effects that last for long periods of time, often for the entire life of the individual. Hormones of the stress system and sex steroids have such effects, which influence the behavior and certain physiologic functions of individuals for life. Exposure of the developing brain to severe and/or prolonged stress may result in hyperactivity/hyperreactivity of the stress system, with resultant amygdala hyperfunction (fear reaction), decreased activity of the hippocampus (defective glucocorticoid-negative feedback, cognition), and the mesocorticolimbic dopaminergic system (dysthymia, novelty-seeking, addictive behaviors), hyperactivation of the HPA axis (hypercortisolism), suppression of reproductive, growth, thyroid and immune functions, and changes in pain perception. These changes may be accompanied by abnormal childhood, adolescent and adult behaviors, including excessive fear ('inhibited child syndrome') and addictive behaviors, dysthymia and/or depression, and gradual development of components of the metabolic syndrome X, including visceral obesity and essential hypertension. Prenatal stress exerted during the period of sexual differentiation may be accompanied by impairment of this process with behavioral and/or somatic sequelae. The vulnerability of individuals to develop varying degrees and/or components of the above life-long syndrome is defined by as yet unidentified genetic factors, which account for up to 60% of the variance. CRH has marked kindling and glucocorticoids have strong consolidating properties, hence both of these hormones are crucial in development and can alone produce the above syndrome. CRH and glucocorticoids may act in synergy, as in acoustic startle, while glucocorticoids may suppress or stimulate CRH, as in the hypothalamus and amygdala, respectively. A CRH type 1 receptor antagonist, antalarmin, inhibits both the development and expression of conditioned fear in rats, and has anxiolytic properties in monkeys. Profound stressors, such as those from sexual abuse, may elicit the syndrome in older children, adolescents and adults. Most frequently, chronic dysthymia and/or depression may develop in association with gastrointestinal complaints and/or the premenstrual tension syndrome. A lesser proportion of individuals may develop the classic posttraumatic stress disorder, which is characterized by hypocortisolism and intrusive and avoidance symptoms; in younger individuals it may present as dissociative personality disorder.
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PMID:Pediatric stress: hormonal mediators and human development. 1264 70

Both omega-6 and omega-3 long-chain polyunsaturated fatty acids (LCPUFAs) modulate TH1 and TH2 cell generation, their cytokine production, and cell proliferation and thus may serve as endogenous anti-inflammatory molecules. LCPUFAs suppress the production of tumor necrosis factor-alpha (TNF-alpha) (and so also of OX40, since it belongs to the family of TNFR) and the expression of Bcl-2, suggesting that these fatty acids have the ability to prevent/suppress autoimmune diseases. Human breast milk contains substantial amounts of both omega-3 and omega-6 fatty acids. This indicates that LCPUFAs present in human breast milk suppress the levels of OX40 and decrease the expression of Bcl-xL and Bcl-2 on exposure to self-antigens and thus, protects against the development of autoimmune diseases in later life. In view of this, I propose that supplementation of appropriate amounts of LCPUFAs during perinatal period protects against atopy, asthma, auto-immune diseases, type 1 and type 2 diabetes mellitus, hypertension, coronary heart disease, metabolic syndrome X, lymphomas, leukemias and other cancers, schizophrenia, depression and other adult diseases in which low-grade systemic inflammation plays a significant role. It is also likely that perinatal supplementation of LCPUFAs in adequate amounts modulates the expression of genes concerned with immune response, angiogenesis, central osmo/sodium and glucose sensors etc. This renders various tissues and organs including T cells and macrophages, endothelial cells, hypothalamic neurons, and various cardiovascular tissues to be able to counteract the pathological mechanisms that tend to induce various adult diseases by blunting the inflammatory responses in those who received adequate amounts of LCPUFAs during the perinatal period compared to those who did not.
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PMID:Perinatal supplementation of long-chain polyunsaturated fatty acids, immune response and adult diseases. 1511 76

A number of metabolic (e.g., abdominal obesity) and psychological (e.g., depression) pathologies commonly present together and have been associated with dysregulation in the hypothalamo-pituitary-adrenal (HPA) axis. Glucocorticoid hormones represent the final product of this classic neuroendocrine axis, and these steroids modulate neuroendocrine, metabolic, and behavioral function. A primary characteristic of the HPA axis is a negative feedback loop, and glucocorticoids act through the brain to inhibit drive to this neuroendocrine system. Slight and chronic perturbations in glucocorticoid levels, below or above normal, throughout the body lead to metabolic (e.g., abdominal obesity) and behavioral (e.g., depression) pathology. Appropriate feedback in the HPA axis is, therefore, critical, and determining how and where glucocorticoids act to impart their feedback effects have been the focus of many laboratories. However, the answer to these questions remain, in part, elusive. In this chapter, I review findings that have led me to reinterpret glucocorticoid feedback in the HPA axis. I propose that, under basal (nonstress) conditions, glucocorticoid feedback is a consequence of the metabolic actions of the adrenal steroid, not a direct effect on brain. This new perspective may provide insight into the etiology of diseases such as major depression and the metabolic syndrome X, and might explain the commonly observed coexistence of affective and metabolic disturbances.
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PMID:Reinterpretation of basal glucocorticoid feedback: implications to behavioral and metabolic disease. 1519 77