Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To clarify whether various neuropeptides found in the hypothalamus act directly on a pituitary adenoma causing Nelson's syndrome, we examined the influence of these peptides on the secretion of immunoreactive ACTH, beta-endorphin, and melanotropins, the proopiomelanocortin (POMC)-derived peptides, by the cultured pituitary adenoma from a patient with Nelson's syndrome. Results showed that somatostatin-14 and somatostatin-28 suppressed the secretion of POMC-derived peptides by the adenoma and that somatostatin-28 was as potent as somatostatin-14. Other neuropeptides such as arginine vasopressin, vasoactive intestinal polypeptide, and oxytocin stimulate the secretion of POMC-derived peptides. Substance P, TRF, Met-enkephalin and Leu-enkephalin were also found to modulate the secretion of POMC-derived peptides. This suggests that the adenoma may have multiple receptors to various neuropeptides.
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PMID:Effects of various neuropeptides on the secretion of proopiomelanocortin-derived peptides by a cultured pituitary adenoma causing Nelson's syndrome. 612 87

The AtT-20/D16-16 mouse pituitary tumor cell secretes corticotropin (ACTH) in response to corticotropin-releasing factor (CRF), (-)-isoproterenol, and vasoactive intestinal peptide (VIP). These responses are associated with a rapid increase in cyclic AMP formation. Somatostatin (SRIF) markedly decreases the stimulatory effect of CRF, (-)-isoproterenol, and VIP on both cyclic AMP formation and immunoreactive ACTH secretion. Forskolin and cholera toxin, adenylate cyclase activators, also stimulate cyclic AMP formation and ACTH secretion in AtT-20 cells and these responses are all inhibited by SRIF. The ACTH secretory responses to melittin and to the calcium ionophore A23187, neither of which increases cyclic AMP in AtT-20 cells, were not inhibited by SRIF. SRIF did not affect the binding of a tritiated beta-adrenergic receptor antagonist to AtT-20 membranes nor did it decrease basal cyclic AMP formation even in the presence of excess phosphodiesterase inhibitor, indicating that the reduction of cyclic AMP levels by SRIF did not involve either an interference with beta-adrenergic agonist binding to receptors or stimulation of cyclic AMP degradation. These results indicate that the inhibition of CRF-, (-)-isoproterenol-, and VIP-stimulated ACTH secretion by SRIF may be regulated by its inhibitory action on adenylate cyclase.
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PMID:Somatostatin inhibits multireceptor stimulation of cyclic AMP formation and corticotropin secretion in mouse pituitary tumor cells. 612 32

The response of pituitary adenomas obtained surgically from patients with Cushing's disease of Nelson's syndrome to synthetic ovine corticotropin-releasing factor (CRF), vasopressins, somatostatin-28, dexamethasone, 3-isobutylmethylxanthine or high [K+] was examined in vitro by measuring the amount of pro-opiomelanocortin (POMC)-derived peptides secreted into the culture medium. CRF did not stimulate the secretion of adrenocorticotropin-, beta-endorphin-, or gamma 3-melanotropin-like peptides from the pituitary adenomas at concentrations ranging from 1 x 10(-13) M to 1 x 10(-7) M whereas vasopressins, 3-isobutyrl-methylxanthine and high [K+] increased, while somatostatin-28 and dexamethasone suppressed, the secretion of these POMC-derived peptides. These findings suggest that either the pituitary ACTH-producing tumors have lost their receptors to CRF or their post-receptor mechanism to CRF is not functional.
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PMID:Pituitary adenomas that caused Cushing's disease or Nelson's syndrome are not responsive to ovine corticotropin-releasing factor in vitro. 613 Jan 1

To study the effect of starvation on hypothalamic beta-endorphin and somatostatin (SRIF) concentrations in relation to starvation induced anestrus, groups of 8 rats were fed 50% of their normal daily chow consumption. Rats were sacrificed after 4, 8, 12, and 16 days during diestrus or anestrus. beta-endorphin concentrations decreased in the preoptic suprachiasmatic area (0.52 +/- 0.13 vs 0.21 +/- 0.05 ng/mg tissue wet weight) and increased in the posterior hypothalamus (0.31 +/- 0.06 vs 0.57 +/- 0.11 ng/mg) after 4 days of starvation. No significant change occurred in the arcuate nucleus or in the median eminence. On day 8 and 12 of starvation, beta-endorphin was unaltered in all areas compared to controls. Vaginal smears showed constant diestrus in a significant number of rats (5 out of 8) after 12 days. beta-endorphin concentrations in the arcuate nuclei of these rats were significantly reduced on day 16 (1.00 +/- 0.33 vs 0.30 +/- 0.11 ng/mg). The SRIF levels changed only in the median eminence with increased concentrations on day 12 (45.2 +/- 8.4 vs 79.5 +/- 14.8 ng/mg). At this time serum levels of luteinizing hormone (LH), prolactin (PRL), and growth hormone (GH) were significantly reduced. The results indicate that changes in hypothalamic beta-endorphin accompany the events leading to starvation induced anestrus.
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PMID:Changes of beta-endorphin and somatostatin concentrations in different hypothalamic areas of female rats after chronic starvation. 613 89

An intracisternal injection of somatostatin-28 produced hyperthermia in rats at cold, thermoneutral, warm ambient temperatures. The hyperthermic response to somatostatin-28 was not prevented by pretreatment of rats with the following agents: alpha-methylparatyrosine, phenoxybenzamine, propranolol, sulpiride, atropine, methysergide or naloxone. Somatostatin-28 prevented hypothermia induced by bombesin and gamma-MSH when it was administered simultaneously, but it left the hyperthermic response to TRH intact. The results indicate that somatostatin-28 produces hyperthermia by elevating a "set point" or regulated level of temperature. Under the conditions tested, the hyperthermic response to somatostatin-28 does not appear to be dependent on muscarinic cholinergic, serotonergic, alpha- or beta-adrenergic, dopaminergic or endogenous opiate system.
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PMID:Hyperthermic action of somatostatin-28. 613 57

Somatostatin-14 (SRIF) inhibits both hormone- and forskolin-stimulated cyclic adenosine 3':5'-monophosphate (cyclic AMP) formation in tumor cells of the mouse anterior pituitary (AtT-20/D16-16). However, long-term pretreatment of cells with SRIF modifies the responsiveness of this system in two ways: The response of adenylate cyclase to stimulatory agents is enhanced, whereas the ability of SRIF to inhibit stimulated cyclic AMP formation is reduced. The supersensitive adenylate cyclase response and the SRIF desensitization were dependent on the concentration and duration of SRIF pretreatment. Enhancement of forskolin-stimulated cyclic AMP formation occurred within 4 hr, whereas that of corticotropin-releasing-factor-, (-)-isoproterenol-, and vasoactive intestinal peptide-induced cyclic AMP accumulation required 16 hr of pretreatment. The elevated responses to each of these stimulants were due to increases in their maximal ability to stimulate cyclic AMP formation. Cycloheximide treatment blocked the enhanced cyclic AMP response induced by SRIF pretreatment, suggesting a requirement for protein synthesis. In membrane preparations, SRIF pretreatment facilitated activation of adenylate cyclase by forskolin, sodium fluoride, and guanosine 5'-(beta,tau-imido)-triphosphate without affecting basal activity. These results suggest that desensitization of an inhibitory input to adenylate cyclase is accompanied by a supersensitivity of adenylate cyclase to stimulatory agents through a process requiring protein synthesis.
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PMID:Somatostatin pretreatment desensitizes somatostatin receptors linked to adenylate cyclase and facilitates the stimulation of cyclic adenosine 3':5'-monophosphate accumulation in anterior pituitary tumor cells. 614 35

Addition of somatostatin (SRIF) inhibits corticotropin-releasing factor- and forskolin-stimulated cyclic AMP accumulation and adrenocorticotropin hormone secretion from mouse anterior pituitary tumor cells (AtT-20/D16-16). However, prior exposure of these cells to SRIF reduced the potency of SRIF to inhibit both corticotropin-releasing factor- and forskolin-stimulated cyclic AMP accumulation and adrenocorticotropin hormone release. This SRIF desensitization is time- and concentration-dependent and reversible. Cross-desensitization to SRIF analogs also occurred whereas SRIF pretreatment did not affect the inhibition by SRIF of 8-bromo-cyclic AMP-stimulated adrenocorticotropin hormone release or did it affect basal cyclic AMP levels, protein content or phosphodiesterase activity. These data indicate that SRIF can regulate the sensitivity of its own receptor and that SRIF desensitization may involve either a down-regulation of SRIF receptors or an uncoupling of these inhibitory receptors from adenylate cyclase.
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PMID:Somatostatin desensitization: loss of the ability of somatostatin to inhibit cyclic AMP accumulation and adrenocorticotropin hormone release. 614 43

Because hypothalamic and extrahypothalamic levels of thyrotropin-releasing hormone immunoreactivity (TRH-IR) undergo profound changes during the prenatal and early postnatal period in rats, similar effects with advanced aging were anticipated. For this reason we measured hypothalamic and reproductive tissue levels of TRH-IR, hypothalamic levels of somatostatin (SRIF), and beta-endorphin (EP), serum levels of prolactin (Prl), growth hormone (GH), thyrotropin (TSH), and thyroxine (T4) in young, sexually mature and 24-28 month-old male Long-Evans and Sprague-Dawley rats. Hypothalamic and prostatic levels of TRH-IR were consistently reduced as were the levels of T4 in old rats compared to young controls. Aging did not change the ratio of TRH to the major TRH-like peptide in prostates, as determined by high pressure liquid chromatography (HPLC) or the levels of hypothalamic SRIF and EP. All of the hypothalamic TRH-IR in both old and young male rats consisted of TRH by HPLC. Falling hypothalamic TRH levels and TRH secretory capacity may play a role in the blunted TSH response to cold stress in old rats.
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PMID:Thyrotropin-releasing hormone levels decrease in hypothalamus of aging rats. 615 Nov 24

The present report concerns the immunocytochemistry of various peptide hormones and in particular their location in nervous structures. However, since the hormones observed in the neuroadenohypophysis and the digestive tractus have been examined elsewhere, they have been excluded from this study, except when considered outside there precise areas. The immunocytology of the following neuropeptides is presented, especially the particular details related to their demonstration: 1) The hypothalamic hypophysiotropic factor: LH-RF, SRIF, TSH-RF; derivatives from the so-called proopiocortine found by Mains and Eipper (1977), namely beta-LPH, enkephalins, endorphins, alpha-MSH- and ACTH-like antigens; 2) Prolactin and somathormone found outside the pituitary; 3) Gastro-intestinal hormones and their location outside the digestive hormones and their location outside the digestive mucosa, namely VIP, CCK, substance P; 4) Angiotensin II in nervous structures; 5) Neurotensin; 6) Thyrocalcitonin; 7) Relaxin, and the problem of its presence in the adult male genital tract. New data in invertebrate located vertebrate neuropeptides-like antigens in the nervous structures of pro-chordates (Ascidians) insects, crustaceans, annelids. These last findings underline the extensive significance of such hormonal molecules previously considered to be specific for vertebrates.
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PMID:Immunocytochemistry of polypeptide hormones: a review. 616 60

Acrolein was examined as an alternative fixative to formaldehyde for immunocytochemical localization of neuropeptides in the rat brain. A brief (5 min) vascular perfusion with a 5% acrolein solution allowed the identification of thyrotropin-releasing hormone (TRH), vasoactive intestinal peptide (VIP), somatostatin (SRIF), neurotensin (NT), methionine enkephalin (Menk), adrenocorticotropic hormone (ACTH), tyrosine hydroxylase (TH), and luteinizing hormone-releasing hormone (LHRH) in fibers and perikarya within the central nervous system of the rat using the peroxidase-antiperoxidase (PAP) technique. Acrolein appears to be particularly valuable for immunocytochemistry, as it 1) stabilizes heterogeneous peptides and proteins rapidly and effectively, 2) retains antigenicity, and 3) preserves morphological detail.
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PMID:Acrolein: a fixative for immunocytochemical localization of peptides in the central nervous system. 618 5


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