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)

Current evidence indicates that the neuroendocrine system is the highest regulator of immune/inflammatory reactions. Prolactin and growth hormone stimulate the production of leukocytes, including lymphocytes, and maintain immunocompetence. The hypothalamus-pituitary-adrenal axis constitutes the most powerful circuit regulating the immune system. The neuropeptides constituting this axis, namely corticotrophin releasing factor, adrenocorticotrophic hormone, alpha-melanocyte stimulating hormone, and beta-endorphin are powerful immunoregulators, which have a direct regulatory effect on lymphoid cells, regulating immune reactions by the stimulation of immunoregulatory hormones (glucocorticoids) and also by acting on the central nervous system which in turn generates immunoregulatory nerve impulses. Peptidergic nerves are major regulators of the inflammatory response. Substance P and calcitonin gene-related peptide are pro-inflammatory mediators and somatostatin is anti-inflammatory. The neuroendocrine regulation of the inflammatory response is of major significance from the point of view of immune homeostasis. Malfunction of this circuit leads to disease and often is life-threatening. The immune system emits signals towards the neuroendocrine system by cytokine mediators which reach significant blood levels (cytokine-hormones) during systemic immune/inflammatory reactions. Interleukin-1, -6, and TNF-alpha are the major cytokine hormones mediating the acute phase response. These cytokines induce profound neuroendocrine and metabolic changes by interacting with the central nervous system and with many other organs and tissues in the body. Corticotrophin releasing factor functions under these conditions as a major co-ordinator of the response and is responsible for activating the ACTH-adrenal axis for regulating fever and for other CNS effects leading to a sympathetic outflow. Increased ACTH secretion leads to glucocorticoid production. alpha-melanocyte stimulating hormone functions under these conditions as a cytokine antagonist and an anti-pyretic hormone. The sympathetic outflow, in conjunction with increased adrenal activity. leads to the elevation of catecholamines in the bloodstream and in tissues. Current evidence suggests that neuroimmune mechanisms are essential in normal physiology, such as tissue turnover, involution, atrophy, intestinal function, and reproduction. Host defence against infection, trauma and shock relies heavily on the neuroimmunoregulatory network. Moreover, abnormalities of neuroimmunoregulation contribute to the aetiology of autoimmune disease, chronic inflammatory disease, immunodeficiency, allergy, and asthma. Finally, neuroimmune mechanisms play an important role in regeneration and healing.
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PMID:The immune effects of neuropeptides. 891 48

The ability of gastrin-releasing peptide to inhibit the release of growth hormone and prolactin by a hypothalamic mechanism has been previously reported. To determine whether or not these effects involved the hypothalamic dopaminergic neurons, ovariectomized female rats were pretreated with the dopamine receptor blocker, pimozide (0.6 mg/kg, SC), or the diluent 35 min prior to administration of gastrin-releasing peptide (2 micrograms in 2 microliters 0.9% NaCl) into the third ventricle. The elevation in plasma growth hormone in response to growth hormone-releasing factor (GRF; 1 microgram/kg, i.v.) was blocked by gastrin-releasing peptide as previously reported following pretreatment with the diluent, but occurred following the injection of pimozide, reversing the inhibitory action of gastrin-releasing peptide. Some control animals that were injected with the pimozide vehicle exhibited elevated plasma prolactin levels compared to levels in uninjected controls. Gastrin-releasing peptide significantly lowered plasma prolactin concentrations in this group of animals. As expected, plasma prolactin levels were elevated following pimozide treatment due to the removal of inhibitory dopaminergic control. Prolactin concentrations were unresponsive to gastrin-releasing peptide treatment in this paradigm and remained elevated throughout the 40-min duration of sampling. We interpret these data to indicate that gastrin-releasing peptide exerts its inhibitory actions on the release of growth hormone and prolactin through a dopaminergic mechanism. Gastrin-releasing peptide may elicit the release of dopamine from tuberoinfundibular neurons, which a) stimulates release of somatostatin, thus inhibiting the release of growth hormone, and b) reaches the pituitary directly via the hypophysial portal vessels to inhibit the release of prolactin from the lactotropes.
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PMID:Role of dopamine in the inhibitory control of growth hormone and prolactin release by gastrin-releasing peptide. 896 84

RECOMMENDED TREATMENTS: The different therapeutic strategies proposed for pituitary adenomas are relatively well-known thanks to numerous studies evaluating their effect on outcome. Unfortunately, large comparative clinical trials are difficult to construct due to the small number of cases of this rare condition. Therapeutic recommendations are thus generally based on the opinion of recognized experts. MICROADENOMA: Small (< 10 mm) prolactin-secreting adenomas should be treated surgically, generally by transsphenoidal adenomectomy, or medically by dopaminergic agonists: bromocriptin, quinagolide or cabergolin (the two latter drugs are more effective and better tolerated than their parent compound bromocriptin). MACROADENOMA: The expected success rate for surgical treatment of macroadenomas is low and dopaminergic agonists is generally recommended (including cases with visual impairment since the effect can be very rapid). Prolactin levels can be lowered and tumor volume reduced (in > 70% of cases). ACROMEGALY: Surgery is the firs intention treatment for acromegaly. In case of unsuccessful surgery (the criteria for "cure" are much more strict in 1998 than previously), somatostatin analog and/or hypothalamo-hypophyseal radiotherapy are recommended. Slow release formulations of somatostatin analogs can now be given by monthly (octreotide LP) or biweekly (lanreotide LP) injections. CUSHING'S DISEASE: Cure can be achieved in > 80% of cases with surgery, the first intention treatment of choice. If surgery is unsuccessful, radiotherapy can be proposed associated with anticortisol drugs (mitotane), if needed, while waiting for the late effect of radiotherapy. CLINICALLY SILENT ADENOMAS: Non-functional adenomas should be operated. Some propose adjuvant radiotherapy in all cases and others only if residual tissue persists post-operatively.
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PMID:[Treatment of pituitary adenoma]. 989 1

A bidirectional interaction exists between sleep electroencephalogram (EEG) and endocrine activity in various species including humans. Various hormones (peptides, steroids) were shown to participate in sleep regulation. A keyrole was shown for the reciprocal interaction between sleep-promoting growth hormone-releasing hormone (GHRH) and sleep-impairing corticotropin-releasing hormone (CRH). Changes in the GHRH:CRH ratio result in changes of sleep-endocrine activity. There is good evidence that the change of this ratio in favor of CRH contributes to aberrances of sleep during aging and depression. Besides of GHRH ghrelin and galanin promote SWS, whereas somatostatin is another sleep-impairing factor. NPY acts as a CRH antagonist and induces sleep onset. Prolactin enhances rapid eve-movement sleep (REMS) in rats. SWS is enhanced in patients with prolactinoma. Other studies on the influence of prolactin of human sleep are lacking. There is a controversy whether CRH promotes REMS. In humans vasocactive intestinal polypeptide (VIP) appears to play a role in the temporal organization of sleep, since after VIP administration the NREMS-REMS cycle decelerated. Several neuroactive steroids (pregnenolone, progesterone, allopregnanolone, dehydroepiandrosterone) exert specific effects on sleep EEG via GABAA receptors. Cortisol appears to enhance REMS. Finally gonadal hormones participate in sleep regulation. Estrogen replacement therapy and CRH-1 receptor antagonism in depression are beneficial clinical applications of the basic research presented here.
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PMID:Sleep and endocrine regulation. 1270 62

Twenty-four hour rhythmicity of serum prolactin and median eminence and anterior pituitary content of dopamine (DA), serotonin (5HT), gamma-aminobutyric acid (GABA), taurine and somatostatin were examined in 2 months-old and 18-20 months-old Wistar male rats. The concentration of prolactin was higher in aged rats, with peaks in both groups of rats at the early phase of the activity span. Median eminence DA content of young rats attained its maximum at the middle of rest span and decreased as prolactin levels augmented while the lowest values of adenohypophysial DA were observed at the time of prolactin peak. DA rhythmicity disappeared in aged rats. GABA content of median eminence and adenohypophysis was lower in aged rats, with maximal values of median eminence GABA at light-dark transition in young rats and at the second half of activity span in aged rats. Serum prolactin correlated positively with median eminence GABA in young rats and negatively with pituitary GABA in young and aged rats. Median eminence somatostatin peaked at the beginning of the activity phase (young rats) or at the end of the rest phase (aged rats). Prolactin levels and somatostatin content correlated significantly in young rats only. Median eminence and pituitary 5HT and taurine content did not change with age. The results indicate disruption of prolactin regulatory mechanisms with aging in rats.
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PMID:Changes of prolactin regulatory mechanisms in aging: 24-h rhythms of serum prolactin and median eminence and adenohypophysial concentration of dopamine, serotonin, (gamma-aminobutyric acid, taurine and somatostatin in young and aged rats. 1472 63

It is well established that disruption of apoptosis may lead to tumor initiation, progression or metastasis. It is also well documented that many anticancer drugs induce apoptosis. In the earlier studies, the dopamine D2 receptor agonist bromocriptine (BC) and somatostatin analog octreotide (OCT) were found to inhibit the growth of the estrogen-induced rat prolactinoma. Our previous investigations, applying the TUNEL method showed the involvement of the pro-apoptotic effect in the action of BC, and to a lesser degree, in the action of OCT. The aim of the present study was to investigate whether the pro-apoptotic action of these drugs involves the increased expression of Bax--a member of Bcl-2 protein family which is known to play an important role in the regulation of apoptosis. Male four-week Fisher 344 rats were used in the experiment. Capsules containing diethylstilboestrol (DES) were implanted subcutaneously. Six weeks after the implantation the rats were given OCT (2 x 25 microg/animal/24), BC (3 mg/kg b.w./24 h) or OCT and BC at the above doses for 10 days. Bax expression was detected by immunohistochemistry. Prolactin (PRL) in blood serum was measured by radioimmunoassay (RIA). It has been found that both OCT and BC, alone or in combination, significantly reduce the tumor weight. Both OCT and BC suppressed PRL levels, but the inhibitory effect of BC was stronger than that of OCT. It has been found that the treatment with OCT and BC, alone or in combination, causes a significant increase in Bax expression in the rat prolactinoma cells. Our findings indicate that anti-tumoral action of bromocriptine and to some extent the action of octreotide in the experimental rat prolactinoma is connected with the induction of apoptosis and is associated with increased Bax expression.
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PMID:The effect of octreotide and bromocriptine on expression of a pro-apoptotic Bax protein in rat prolactinoma. 1504 98

Radiation therapies of pituitary adenomas induce an increase in fibroses and nuclear pleomorphism. Most growth hormone (GH) secreting pituitary adenomas react to somatostatin analogues by a distinct decrease of GH secretion. In two thirds, levels of IGF-1 can be normalized. Some cases show a shrinkage of adenomas that correlates with fibrosis of the tumor. With these drugs, thyroid stimulating hormone secreting adenomas can also be treated. Prolactin secreting adenomas are mostly treated primarily with dopamine agonists. Up to 90% of cases show a strong decrease in hormone secretion and a distinct shrinkage of the adenomas based on strong decrease in adenoma cell volume. Long-term medication with high doses of glucocorticoids induces Crooke's cells in the anterior pituitary. These are suppressed ACTH cells and characterized by increased numbers of large lysosomes and dense bundles of cytofilaments.
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PMID:[Effects of irradiation therapy and inhibiting drugs on the pituitary and its adenomas]. 1636 59

Prolactin, estrogen, and progesterone together induce proliferation of the mammary glands with a coincident increase in the IgA-secreting plasma cells in the tissue. Of these three hormones, Prolactin is the most effective single peptide in stimulating IgA production. Vasoactive intestinal peptide (VIP) and somatostatin have also been shown to modulate IgA production. Although more extensive investigation is required, delineation of an immune axis involving prolactin, VIP, and somatostatin in mucosal immune tissue such as mammary gland is a promising area of research with clinical relevance to neonatal resistance to infection.
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PMID:Modulation of IgA synthesis by neuroendocrine peptides. 1841 Nov 68

Cortistatin (CST), a novel neuropeptide, shows high structural homology and functional resemblance with somatostatin. CST binds with high affinity to all somatostatin receptors, and contrary to somatostatin, is also able to bind with MrgX2 and GH secretagogue receptor of ghrelin (GHS-R1) receptors. The aim of the present investigation was to evaluate in vivo the effect of peripheral administration of cortistatin on pituitary hormone release in comparison with somatostatin (SS) treatment. Adult male rats used in the experiment, were given peripheral injection of cortistatin, somatostatin or vehicle. Blood was withdrawn 60 and 120 minutes thereafter. We found short lasting significant decrease of GH concentration as a result of administration of CST and SS when compared with saline injected controls. Prolactin levels were increased 60 min after cortistatin but not to somatostatin injection. There was no effect of CST on both LH and FSH concentration; however, SS administration influenced gonadotropin secretion. We conclude that cortistatin play a regulatory role in pituitary secretion. Moreover, some differences have been found when compared cortistatin to somatostatin. Thus, when analyzing the mechanism of cortistatin activity it is worth to consider the effect of binding with receptors of somatostatin, specific receptor for CST (MrgX2) and GHS-R.
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PMID:Cortistatin and pituitary hormone secretion in rat. 1943 17

The parenchyma of the anterior pituitary gland is constituted of distinct specialized glandular cell types, some of them being able to secrete two, or more, genetically related hormones. The synthesis and the release of each hormone is a discontinuous process controlled by a variety of chemical signals of hypothalamic and peripheral origin. These signals, namely neuropeptides, may cross-react at the level of one cell type and each signal may govern the activity of more than one cell type. Such integrated systems hamper the analysis of binding and secretion coupling of regulatory neuropeptides at the cellular and molecular levels. Prolactin (PRL) and growth hormone (GH) rat clonal pituitary tumor-derived cell lines (GH cells) by contrast offer a reductionist model suitable for such investigations on TRH and somatostatin hypophysiotropic neuropeptides and on their hormonal regulation, as reviewed in this paper. The tetradecapeptide somatostatin inhibits similarly PRL and GH release by GH cells. Using (125)I-Tyr-somatostatin, specific binding sites were characterized; their occupation presents dose dependence and stereospecific requirements similar to the induction of the inhibition of hormone release. In cells cultured in serum-supplemented media, TRH regulates in a biphasic manner somatostatin binding sites: TRH acutely increases and chronically decreases their number without altering their affinity. In cells cultured in serum-free media, TRH competes with (125)I-Tyr-somatostatin and displace it with a similar affinity and nearly identical efficiency as unlabelled somatostatin. These effects of TRH are totally prevented by preculturing the cells in a medium supplemented with tri-iodotyronine, which in addition increases somatostatin binding capacity. The tripeptide TRH stimulates similarly the acute release of PRL and GH by GH cells. By contrast, long-term exposure to TRH inversely regulates the production of both hormones, PRL being augmented and GH inhibited. This results from an opposite regulation of the transcription of the rPRL and rGH genes and of the half-life of their respective encoded mRNA, the stimulation of the rPRL gene being rapid and transient. These effects are mediated by the occupation of specific binding sites, extensively studied using (3)H-TRH, displaying the same dose- and time-dependence, as well as stereospecific requirements, as the regulation of hormone secretion. Factor regulating per se the PRL and GH secretion also alter TRH interaction with GH cells. TRH and tri-iodotyronine both down-regulate the number of TRH binding sites while estrogens or glucocorticoids augment them. TRH binding and secretion coupling are not always regulated in parallel. Evidences for plasma membrane located events were reported for TRH, but also for its internalization. Thus the subcellular localization of the initial signal(s) triggering acute hormone release on the one hand and alteration of specific genes transcription on the other hand is still debated.
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PMID:Multihormonal regulation of the pituitary gland binding and secretory responses to hypothalamic neuropeptides in rat GH pituitary strains in culture. 2049 10


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