Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P61278 (somatostatin)
 22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

This review addresses some relevant aspects of the aging of the neuroendocrine system, particularly the reproductive and the adrenocortical axis. Deterioration of the reproductive function, one of the most striking endocrine alterations occurring in aging, is related to a complex interplay of factors. They comprise alterations occurring at the level of all the three components of the reproductive axis, the gonads, the pituitary and the brain, acting synergistically to disrupt the normal pulsatile release of gonadotropins. Particular relevance is given to the neurotoxic action of estrogens during the constant estrous phase occurring in aged female rodents, at the level of hypothalamic nuclei regulating gonadotropin secretion. This effect, to be found also in women during the anovulatory period of the perimenopause, would worsen the dysregulation of the central mechanisms controlling the reproductive function. The activity of the adrenocortical (HPA) axis increases with advancing age in rodents but also, although less strikingly, in humans. The main alteration which can be evidenced in both species is a delayed post-stimulus decline in plasma corticosteroid levels, indicating a diminished sensitivity to glucocorticoids of HPA axis feedback regulation in the elderly. Increased exposure to the highly catabolic adrenal glucocorticoids appears to be associated to a loss of cerebral neurons, particularly in the hippocampus, and the emergence of cognitive deficits in the aged rats. The relevance of experimental data performed in rodents to healthy and pathological human aging is extensively discussed. Finally, this chapter considers the age-related impairment in growth hormone secretion, a common finding of all the animal species investigated so far. The etiology of the hyposomatotropism of aging is namely linked to a progressive defect in growth hormone releasing hormone-producing hypothalamic neurons, although alterations of somatostatin-producing neurons have also been described. This background knowledge makes the use of neuroactive compounds aimed at restoring the physiologic function of hypothalamic hypophysiotropic hormones a rational approach to rectify the alterations of the neuroendocrine system occurring in elderly individuals.
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PMID:Age-related alterations in gonadotropin, adrenocorticotropin and growth hormone secretion. 132 12

Corticotropin-releasing hormone (CRH), somatostatin (SOM), delta-sleep-inducing peptide (DSIP), neuropeptide Y (NPY), beta-endorphin (beta-END), and vasopressin (AVP), which are regarded as being involved in the HPA-regulation were investigated in lumbar CSF of 44 suicide attempters. The patients were diagnosed according to the DSM-III-R, and rated with the MADRS. The neuropeptides were compared with the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA) in CSF and with post-dexamethasone plasma cortisol. We found strong correlations between CRH and the peptides SOM and beta-END. The latter also correlated positively with SOM. There were no differences between men and women. Patients with major depressive disorders had significantly lower SOM, CRH, and DSIP than other patients. Both SOM and beta-END correlated negatively with post dexamethasone plasma cortisol in all patients. We found no significant relationships between neuropeptides and CSF 5-HIAA. Patients who had made previous suicide attempts had significantly lower CRH than those who had not. No other significant associations between neuropeptides and suicidal subgroups of patients appeared, and there was no indication of specific neuropeptide patterns in patients who later completed suicide. Intercorrelations of some neuropeptides and low SOM and DSIP in major depressed patients are findings in line with those by others.
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PMID:HPA-related CSF neuropeptides in suicide attempters. 137 70

We have examined corticotropin releasing hormone (CRH), arginine vasopressin (AVP) and somatostatin (SOM) mRNA expression and peptide content in the rat hypothalamus from day 20 of fetal life (F20) to the fifteenth day of postnatal life (P15). During this time, hypothalamic CRH mRNA levels did not change significantly, whereas there was a gradual six-fold rise in CRH peptide levels. AVP mRNA levels fell three-fold between F20 and P1 and increased six-fold between P1 and P15. AVP peptide levels increased three-fold, with most of the rise occurring between P1 and P15. From F20 to P15, SOM mRNA and peptide levels rose four- and eight-fold, respectively. The changes in the levels of these three hypothalamic gene products correlate with the previously described alterations in the responsiveness of the HPA axis observed in fetal and early postnatal rats, suggesting a role for these neuropeptides in the modulation of the HPA axis during this developmental period.
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PMID:Developmental expression of corticotropin releasing hormone messenger RNA and peptide in rat hypothalamus. 257 25

Multiple communicative pathways among the nervous, endocrine and immune systems facilitate physiological immunoregulation. Spinal cord injury (SCI) patients have decreased natural (NK cell) and adaptive (T cell) immune function and reduced blood levels of cellular adhesion molecules (CAMs) that participate in immune function and wound healing. We found decreased LFA-1 and VLA-4 on peripheral blood leukocytes in SCI patients and lower levels of CAMs in SCI patients with pressure ulcers than in those without them. SCI might affect immune cells and immune responsiveness by: (1) disrupting the outflow of signals from the sympathetic nervous system to lymphoid tissues and their blood vessels as well as the returning afferent signals from these tissues to the brain; (2) immunosuppression caused by the stressors affecting SCI patients; (3) interrupting returning signals to the CNS from the periphery thereby reducing facilitation of immunoregulatory CNS neurons and decreasing their activity; or a combination of all three. SCI patients may develop dysregulation of the sympathetic nervous system that is intimately involved in immune function. Chronic stress mediates immunosuppression by corticosteroids, catecholamines, endorphins and met-enkephalin. The hypothalamus coordinates the response to stress through the release of soluble products from the sympathetic nervous system and hypothalamic-pituitary-adrenal axis. Whereas the nervous and endocrine systems are not concerned with immunological specificity, they do influence the intensity, kinetics and localization of immune responses. Products of an activated immune system may generate feedback circuits capable of inhibiting, enhancing or regulating neuronal input. Immune system cells can produce neurologically active peptides including ACTH, CRF, growth hormone, thyrotropin, prolactin, human chorionic gonadotropin, endorphin, enkephalins, substance P, somatostatin and VIP. Cytokines are likely important mediators of the HPA response to immune stimuli.
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PMID:Immune system-neuroendocrine dysregulation in spinal cord injury. 898 97

The effect of amitriptyline upon hypothalamic-pituitary-adrenal [HPA]-system-regulating neuropeptides (corticotropin-releasing hormone [CRH], vasopressin, somatostatin) was studied in a group of depressed elderly patients and controls. A first lumbar puncture was performed in 37 depressed in-patients. This was followed by a 6-week medication phase with amitriptyline. Upon its completion a second cerebrospinal fluid (CSF) sample was obtained in 18 of these 37 patients. In 25 healthy controls a first lumbar puncture was done eleven of these individuals agreed to take 75 mg/d amitriptyline for 6 weeks and to participate in the follow-up CSF study. Within the group of depressed patients amitriptyline led to a significant decrease of CSF CRH in treatment responders only (F1, 16 = 5.2; P < 0.02). Also, in normal controls CSF CRH concentration tended to decrease with amitriptyline treatment (t-test; P < 0.09). No effects of amitriptyline upon vasopressin or somatostatin were observed. In normal controls (r = 0.4; P < 0.02) and in patients (r = 0.4; P < 0.03) age correlated positively with baseline CSF somatostatin. A trend for CSF CRH to increase with aging was found only in controls (r = 0.3; P < 0.09); patients did not show a significant association here. Finally, CSF neuropeptide concentration at baseline did not differ between the group of depressed patients and healthy controls. Our study corroborates the evolving concept that antidepressants effect various components of the HPA system with the net result of a reduction in its activity. In addition, we found CSF CRH and CSF somatostatin concentrations to be better reflections of age than of depression and, finally, that during aging and during depression the HPA system changes in similar directions.
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PMID:Cerebrospinal fluid concentrations of corticotropin-releasing hormone, vasopressin, and somatostatin in depressed patients and healthy controls: response to amitriptyline treatment. 978 81

It is now largely established that the immune and neuroendocrine systems cross-talk by using similar ligands and receptors. In this context, the thymus-hypothalamus/pituitary axis can be regarded as a paradigm of connectivity in both normal and pathological conditions. For example, cytokines and thymic hormones modulate hypothalamic-pituitary functions: (a) interleukin (IL)-1 seems to upregulate the production of corticotropin-releasing factor and by adrenocorticotropin by hypothalamic neurons and pituitary cells, respectively; (b) thymulin enhances LH secretion. Conversely, a great deal of data strongly indicate that the hypothalamic-pituitary axis plays a role in the control of thymus physiology. Growth hormone (GH) for example, enhances thymulin secretion by thymic epithelial cells (TEC), both in vivo and in vitro, also increasing extracellular matrix-mediated TEC/thymocyte interactions. Additionally, gap junction-mediated cell coupling among TEC is upregulated by ACTH. In a second vein, it was shown that GH injections in aging mice increased total thymocyte numbers and the percentage of CD3-bearing cells, as well concanavalin-A mitogenic response and IL-6 production. In addition to mutual effects, thymus-pituitary similarities for cytokine and hormone production have been demonstrated. Cytokines such as IL-1, IL-2, IL-6, interferon-gamma, transforming growth factor-beta and others can be produced by hypothalamic and/or pituitary cells. Conversely, hormones including GH, PRL, LH, oxytocin, vasopressin and somatostatin can be produced intrathymically. Moreover, receptors for various cytokines and hormones are expressed in both the thymus and the hypothalamus/pituitary axis. Lastly, it is noteworthy that a thymus-pituitary connectivity can also be seen under pathological situations. In this regard, an altered HPA axis has been reported in AIDS, human falciparum malaria and murine rabies, that also show a severe thymic atrophy.
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PMID:Immunoneuroendocrine connectivity: the paradigm of the thymus-hypothalamus/pituitary axis. 987 43

The symptomatology of the fibromyalgia syndrome (FMS) often resembles an alteration in central nervous set points at least in three systems. The patients suffer under chronic pain in the region of the locomotor system, presumably reflecting a disturbed central processing of pain. Anxiety and depression often characterizes the clinical picture. Almost all of the hormonal feedback mechanisms controlled by the hypothalamus are altered. Characteristic for FMS patients are the elevated basal values of ACTH, follicle-stimulating hormone (FSH), and cortisol as well as lowered basal values of insulin-like growth factor 1 (IGF-1, somatomedin C), free triiodothyronine (FT3), and oestrogen. In FMS patients, the systemic administration of the relevant releasing hormones of corticotropin-releasing hormone (CRH), growth hormone-releasing hormone (GHRH), thyreotropin-releasing hormone (TRH), and luteinizing hormone-releasing hormone (LHRH) leads to increased secretion of ACTH and prolactin, whereas the degree to which TSH can be stimulated is reduced. The stimulation of the hypophysis with LHRH in female FMS patients during their follicular phase results in a significantly reduced LH response. All in all, the typical alterations in set points of hormonal regulation that are typical for FMS patients can be explained as a primary stress activation of hypothalamic CRH neurons caused by the chronic pain. In addition to the stimulation of pituitary ACTH secretion, CRH activates somatostatin on the hypothalamic level, which in turn inhibits the release of GH and TSH on the hypophyseal level. The lowered oestrogen levels could be accounted for both via an inhibitory effect of the CRH on the hypothalamic release of LHRH or via a direct CRH-mediated inhibition of the FSH-stimulated oestrogen production in the ovary. Serotonin (5HT), precursors like tryptophan (5HTP), drugs which release 5HT or act directly on 5HT receptors stimulate HPA axis, indicating a stimulatory serotonergic influence on HPA axis function. Therefore activation of the HPA axis may reflect an elevated serotonergic tonus in the central nervous system of FMS patients.
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PMID:Neuroendocrine and hormonal perturbations and relations to the serotonergic system in fibromyalgia patients. 1102 24

A large body of data from a number of different laboratories worldwide has demonstrated a general tendency for reduced adrenocortical responsiveness in CFS. It is still not clear if this is secondary to CNS abnormalities leading to decreased activity of CRH- or AVP-producing hypothalamic neurons. Primary hypofunction of the CRH neurons has been described on the basis of genetic and environmental influences. Other pathways could secondarily influence HPA axis activity, however. For example, serotonergic and noradrenergic input acts to stimulate HPA axis activity. Deficient serotonergic activity in CFS has been suggested by some of the studies as reviewed here. In addition, hypofunction of sympathetic nervous system function has been described and could contribute to abnormalities of central components of the HPA axis. One could interpret the clinical trial of glucocorticoid replacement in patients with CFS as confirmation of adrenal insufficiency if one were convinced of a positive therapeutic effect. If patient symptoms were related to impaired activation of central components of the axis, replacing glucocorticoids would merely exacerbate symptoms caused by enhanced negative feedback. Further study of specific components of the HPA axis should ultimately clarify the reproducible abnormalities associated with a clinical picture of CFS. In contrast to CFS, the results of the different hormonal axes in FMS support the assumption that the distortion of the hormonal pattern observed can be attributed to hyperactivity of CRH neurons. This hyperactivity may be driven and sustained by stress exerted by chronic pain originating in the musculoskeletal system or by an alteration of the CNS mechanism of nociception. The elevated activity of CRH neurons also seems to cause alteration of the set point of other hormonal axes. In addition to its control of the adrenal hormones, CRH stimulates somatostatin secretion at the hypothalamic level, which, in turn, causes inhibition of growth hormone and thyroid-stimulating hormone at the pituitary level. The suppression of gonadal function may also be attributed to elevated CRH because of its ability to inhibit hypothalamic luteinizing hormone-releasing hormone release; however, a remote effect on the ovary by the inhibition of follicle-stimulating hormone-stimulated estrogen production must also be considered. Serotonin (5-HT) precursors such as tryptophan (5-HTP), drugs that release 5-HT, or drugs that act directly on 5-HT receptors stimulate the HPA axis, indicating a stimulatory effect of serotonergic input on HPA axis function. Hyperfunction of the HPA axis could also reflect an elevated serotonergic tonus in the CNS of FMS patients. The authors conclude that the observed pattern of hormonal deviations in patients with FMS is a CNS adjustment to chronic pain and stress, constitutes a specific entity of FMS, and is primarily evoked by activated CRH neurons.
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PMID:Neuroendocrine perturbations in fibromyalgia and chronic fatigue syndrome. 1108 55