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)

The function of bombesin-like peptide, a neurotransmitter present in nerve fibers of elasmobranch rectal glands, is unknown. Since the principal activity of the rectal gland is to secrete chloride, the effects of bombesin on chloride secretion and the role of somatostatin in this response was studied. Bombesin failed to stimulate secretion in rectal glands perfused in the basal state. When added to glands stimulated by a constant infusion of vasoactive intestinal peptide (VIP), bombesin (8 x 10(-7) M) reversibly inhibited chloride secretion by 56 +/- 9.7% and at the same time evoked a 10-fold increase in the liberation of somatostatin into the venous effluent. Inactivation of somatostatin by the addition of cysteamine partially suppressed the inhibitory effect of bombesin on glandular secretion. The effect of bombesin to reduce chloride secretion was completely prevented by the calcium channel blocker nifedipine, which inhibits neurotransmitter release. These results suggest that bombesin inhibits the effect of VIP to stimulate chloride secretion by releasing somatostatin from neurosecretory nerve terminals within the rectal gland.
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PMID:Somatostatin mediates bombesin inhibition of chloride secretion by rectal gland. 197 71

Calcium (Ca2+) ion concentrations that are achieved intracellularly upon membrane depolarization or activation of phospholipase C stimulate adenylate cyclase via calmodulin (CaM) in brain tissue. In the present study, this range of Ca2+ concentrations produced unanticipated inhibitory effects on the plasma membrane adenylate cyclase activity of GH3 cells. Ca2+ concentrations ranging from 0.1 to 0.8 microM exerted an increasing inhibition on enzyme activity, which reached a plateau (35-45% inhibition) at around 1 microM. This inhibitory effect was highly cooperative for Ca2+ ions, but was neither enhanced nor dependent upon the addition of CaM (1 microM) to EGTA-washed membranes. The inhibition was greatly enhanced upon stimulation of the enzyme by vasoactive intestinal peptide (VIP) and/or GTP. Prior exposure of cultured cells to pertussis toxin did not affect the inhibition of plasma membrane adenylate cyclase activity by Ca2+, although in these membranes, hormonal (somatostatin) inhibition was significantly attenuated. Maximally effective concentrations of Ca2+ and somatostatin produced additive inhibitory effects on adenylate cyclase. The addition of phosphodiesterase inhibitors demonstrated that inhibitory effects of Ca2+ were not mediated by Ca2(+)-dependent stimulation of a phosphodiesterase activity. These observations provide a mechanism for the feedback inhibition by elevated intracellular Ca2+ levels on cAMP-facilitated Ca2+ entry into GH3 cells, as well as inhibitory crosstalk between Ca2(+)-mobilizing signals and adenylate cyclase activity.
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PMID:Potent and cooperative feedback inhibition of adenylate cyclase activity by calcium in pituitary-derived GH3 cells. 197 2

There is increasing evidence that neuropeptide modulation of the immune response is an important physiological phenomenon which involves the interaction of peptidergic neuromodulators with specific neuropeptide receptors on the plasma membrane of immune effector cells. Many studies have examined the effect of neuropeptides on mitogen-induced lymphocyte proliferation and immunoglobulin synthesis but very little is known about specific lymphokine production. In this study, we describe the effect of somatostatin (SOM) and vasoactive intestinal peptide (VIP) on interferon gamma (IFN-gamma) production by normal human peripheral blood mononuclear cells (PBMC) stimulated in vitro with polyclonal T cell activator staphylococcal enterotoxin A (SEA). Our findings provide experimental evidence that both SOM and VIP reduce the IFN-gamma production by SEA-stimulated PBMC. This reduction was time- (with maximal effect at 72 h) and dose-dependent (at doses as low as 10(-11) M with maximal effect at concentrations between 10(-9) and 10(-8) M of neuropeptides). This effect was absent in resting PBMC. The meaning of inhibitory effect of VIP and SOM on IFN-gamma production and its role in immune response in vivo are discussed.
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PMID:Somatostatin and vasoactive intestinal peptide reduce interferon gamma production by human peripheral blood mononuclear cells. 197 94

Freshly dissociated cerebral cortex cells from adult rats have been used in the present study to determine if dual regulation of cyclic AMP levels by inhibitory and stimulatory agents can be expressed in the mature brain. Somatostatin, an inhibitory agent, barely affected the basal cyclic AMP metabolism while vasoactive intestinal peptide (VIP) and isoproterenol, two stimulatory agents enhanced cyclic AMP production. However, this increase was depressed by somatostatin, which decreased the efficiency, but not the potency, of the effects of the two stimulatory agents on cyclic AMP accumulation.
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PMID:Somatostatin inhibition of VIP- and isoproterenol-stimulated cyclic AMP accumulation in dissociated cells from rat cerebral cortex. 197 62

We have examined the actions of vasoactive intestinal peptide (VIP) and certain other known immune modulators on a nuclear pool(s) of protein kinase C (PKC) in isolated rat splenocyte nuclei. Rat splenocyte nuclei pure by enzymatic and electron microscope criteria demonstrated a time- and concentration-dependent activation of nuclear PKC (nPKC) by VIP. A biphasic pattern of three bell-shaped curves was observed with peak phosphorylation at 10(-15), 10(-9) and 10(-6)M VIP. The phosphorylation of endogenous nuclear substrates was characterized as a PKC-mediated event by use of three known PKC inhibitors, 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H-7), sphingosine, and staurosporine, which produced similar phosphate incorporation measurements. Also, this activity was blocked with the addition of a monoclonal antibody to PKC. Inhibitors of the ability of VIP to activate nPKC included somatostatin, 8-bromo-cAMP, peripheral benzodiazepine receptor modulators, and the PKC inhibitors, sphingosine and staurosporine. These data have direct relevance to our knowledge of cell-mediated immunity.
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PMID:Vasoactive intestinal peptide (VIP) activation of nuclear protein kinase C in purified nuclei of rat splenocytes. 197 36

The effect of vasoactive intestinal peptide (VIP) on the release of growth hormone (GH) from the adenohypophysis of the goat was studied in vitro using the perifusion system. Two perifusion systems were employed to differentiate potential direct effects of VIP on the pituitary from indirect effects mediated through the hypothalamus. The first perifusion system used single chambers housing only pituitary fragments. The second system used two chambers in tandem, one containing hypothalamus and the second the pituitary fragments, the flow passing through the hypothalamic chamber first. VIP (10(-6), 10(-7), 10(-8)M) stimulated significant GH release in both perifusion systems (P less than 0.05, P less than 0.01) in a concentration related fashion. The quantity of GH release induced by the 10(-9)M and 10(-10)M VIP groups were not significant. Further, the GH released from the system that perifused the pituitary alone (10(-8)M VIP) was significantly higher than that containing both the hypothalamus and the pituitary fragments (P less than 0.05). The relative lower GH secretory response to the same dose of VIP applied to the hypothalamus-pituitary suggests that the perifused caprine hypothalamus may release an inhibitory factor, such as somatostatin in vitro. These results suggest that VIP stimulates GH release by acting directly on the adenohypophysis of the goat.
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PMID:Effect of vasoactive intestinal peptide on the release of growth hormone in perifused pituitary and hypothalamus of the goat. 201 23

The effect of intrathecal (i.t.) vasoactive intestinal peptide (VIP) and an analogue of growth hormone releasing factor (GRF) with putative VIP antagonistic property, (Ac-Try1, D-Phe2)-GRF-(1-29), on the nociceptive flexor reflex was studied in decerebrate, spinalized, unanesthetized rats. VIP (10 pM) facilitated the flexor reflex for several minutes. A similar facilitation was induced by the VIP antagonist applied i.t. with a potency 15 times less than that of VIP. Pre-administration of the VIP antagonist dose-dependently antagonized the reflex facilitation by i.t. VIP. In contrast, the reflex facilitation induced by i.t. substance P, somatostatin, calcitonin gene-related peptide and galanin was not influenced by the VIP-antagonist. The VIP antagonist by itself did not depress the flexor reflex over the dose range of 3 pM-3 nM and neither did it block the facilitation of the flexor reflex induced by a brief conditioning electrical stimulus train that activated the C-afferents in skin innervated by the sural nerve. The present results indicate that this GRF analogue is an effective and specific VIP antagonist in the rat spinal cord. Furthermore, it is suggested that VIP may not be involved in the transmission of cutaneous nociceptive information under normal conditions.
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PMID:An analogue of growth hormone releasing factor (GRF), (Ac-Try1, D-Phe2)-GRF-(1-29), specifically antagonizes the facilitation of the flexor reflex induced by intrathecal vasoactive intestinal peptide in rat spinal cord. 206 98

The comparative distribution of peptidergic neural systems in the brain of the euryhaline, viviparous teleost Poecilia latipinna (green molly) was examined by immunohistochemistry. Topographically distinct, but often overlapping, systems of neurons and fibres displaying immunoreactivity (ir) related to a range of neuropeptides were found in most brain areas. Neurosecretory and hypophysiotrophic hormones were localized to specific groups of neurons mostly within the preoptic and tuberal hypothalamus, giving fibre projections to the neurohypophysis, ventral telencephalon, thalamus, and brain stem. Separate vasotocin (AVT)-ir and isotocin (IST)-ir cells were located in the nucleus preopticus (nPO), but many AVT-ir nPO neurons also displayed growth hormone-releasing factor (GRF)-like-ir, and in some animals corticotrophin-releasing factor (CRF)-like-ir. The main group of CRF-ir neurons was located in the nucleus recessus anterioris, where coexistence with galanin (GAL) was observed in some cells. Enkephalin (ENK)-like-ir was occasionally present in a few IST-ir cells of the nPO and was also found in small neurons in the posterior tuberal hypothalamus and in a cluster of large cells in the dorsal midbrain tegmentum. Thyrotrophin-releasing hormone (TRH)-ir cells were found near the rostromedial tip of the nucleus recessus lateralis. Gonadotrophin-releasing hormone (GnRH)-ir cells were present in the nucleus olfactoretinalis, ventral telencephalon, preoptic area, and dorsal midbrain tegmentum. Molluscan cardioexcitatory peptide (FMRF-amide)-ir was colocalized with GnRH-ir in the ganglion cells and central projections of the nervus terminalis. Melanin-concentrating hormone (MCH)-ir neurons were restricted to the tuberal hypothalamus, mostly within the nucleus lateralis tuberis pars lateralis, and somatostatin (SRIF)-ir neurons were numerous throughout the periventricular areas of the diencephalon. A further group of SRIF-ir neurons extending from the ventral telencephalon into the dorsal telencephalon pars centralis also contained neuropeptide Y (NPY)-, peptide YY (PYY)-, and NPY flanking peptide (PSW)-like-ir. These immunoreactivities were, however, also observed in non-SRIF-ir cells and fibres, particularly in the mesencephalon. Calcitonin gene-related peptide (CGRP)-like-ir had a characteristic distribution in cells grouped in the isthmal region and fibre tracts running forward into the hypothalamus, most strikingly into the inferior lobes. Antisera to cholecystokinin (CCK) and neurokinin A (NK) or substance P (SP) stained very extensive, separate systems throughout the brain, with cells most consistently seen in the ventral telencephalon and periventricular hypothalamus. Broadly similar, but much more restricted, distributions of cells and fibres were seen with antisera to neurotensin (NT) and vasoactive intestinal peptide (VIP).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Comparative distribution of neuropeptide-immunoreactive systems in the brain of the green molly, Poecilia latipinna. 208 20

We report the case of a VIPoma diagnosed in a 15-year-old teenager who experienced profuse secretory diarrhea associated with hypokalemia, metabolic acidosis and high plasma levels of vasoactive intestinal peptide (VIP) and pancreatic polypeptide (PP). Angiography showed an abnormal mass in the head of the pancreas. Before surgery, subcutaneous injections (100 micrograms every 8 hours) of the long-acting somatostatin analogue octreotide or SMS 201-995, were administered in order to stabilize the clinical status of the patient and to reduce the intravenous administration of fluid and electrolytes. This treatment resulted in prompt relief of the symptoms and in a partial decrease of the plasma levels of VIP and PP. At subsequent laparotomy, there was a tumour localized in the head of the pancreas, which was completely removed by Whipple resection. The immunohistochemical staining revealed the presence of VIP and PP inside the tumour cells. Two years after surgical resection, the patient is healthy without clinical or laboratory evidence of recurrence.
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PMID:[Vipoma in an adolescent: treatment with a delayed-action somatostatin analog, octreotide or SMS 201-995, and surgical removal]. 217 28

One of the exciting recent developments in endocrinology research has been the introduction of the somatostatin analog, octreotide into clinical practice. Octreotide provides a new therapeutic tool for diseases in which somatostatin or somatostatin-like products are secreted abnormally. Unfortunately, early experience was obtained largely with uncontrolled, compassionate drug use. When clinical information regarding octreotide is critically reviewed, evaluation is hampered by the lack of long-term studies with adequate numbers of patients and controls. Nevertheless, the information available does indicate that octreotide is promising in the acute treatment of some of the manifestations of the carcinoid syndrome, including carcinoid crisis. Similarly, octreotide ameliorates symptoms of other gut neuroendocrine tumors, particularly vasoactive intestinal peptide (VIP)-secreting tumors. Octreotide also has potential in the management of growth-hormone-secreting tumors. Long-term treatment with octreotide for these diseases requires more information regarding alterations in disease progression and development of adverse effects including variable effects on blood sugar regulation and steatorrhoea. Octreotide also has been used in nonmalignant gastrointestinal disorders, but larger studies are necessary before recommendations regarding these applications can be made. The cost of octreotide, as may be expected, is high but is justified for patients with the specific indications outlined in this review. These indications may change as understanding of the drug increases. Octreotide offers promise, particularly as acute treatment for the troublesome symptoms of several neuroendocrine disorders.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Octreotide: a long-acting somatostatin analog. 224 80


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