RESUMEN
Our aim was determine the relationship between cholecystokinin (CCK)-A receptor blockade, glucose levels, insulin secretion and gastric emptying in humans, and to assess the effect of CCK-A blockade on pancreatic polypeptide secretion. After a 12-h fast, six healthy volunteers were given [99mTc]iminodiacetic acid monosodium salt (IDA) intravenously (5 mCi). One hour later they were offered a 577 kcal liquid meal containing [99mTc]diethylenetriaminepentaacetic acid (DTPA) (2 mCi) and glucose (105 g). Scintigraphic gastric and gallbladder activity, and plasma glucose, insulin and pancreatic polypeptide responses were monitored. In a second experiment, a continuous intravenous infusion of loxiglumide (7.5 mg kg h(-1)) was started 60 min before and continued until 120 min after test meal ingestion to block the CCK-A receptors. Gallbladder emptying was blocked by loxiglumide. Loxiglumide accelerated gastric emptying, increased insulin secretion without alteration of glucose profiles, and abolished all phases of the postprandial pancreatic polypeptide response. Blockade of peripheral CCK-A receptors accelerates gastric emptying of liquids with an increase in postprandial insulin levels. The lack of changes in glycaemia suggests that alternative homeostatic mechanisms also control postprandial glucose levels. Inhibition of pancreatic polypeptide release may reflect an independent effect of loxiglumide on vagal control involved in pancreatic polypeptide release.
Asunto(s)
Vaciamiento Gástrico/fisiología , Insulina/sangre , Periodo Posprandial/fisiología , Proglumida/análogos & derivados , Receptores de Colecistoquinina/antagonistas & inhibidores , Adulto , Glucemia/metabolismo , Vaciamiento Vesicular/efectos de los fármacos , Vaciamiento Vesicular/fisiología , Vaciamiento Gástrico/efectos de los fármacos , Humanos , Masculino , Periodo Posprandial/efectos de los fármacos , Proglumida/farmacología , Receptor de Colecistoquinina A , Receptores de Colecistoquinina/metabolismo , Estadísticas no ParamétricasRESUMEN
Severe burn injury is commonly associated with significant changes in intestinal epithelial function. These changes include mucosal atrophy and increased permeability. To date, the mechanism by which burn injury alters intestinal epithelium function are not clear. We used an in vitro model of intestinal epithelium, IEC-6 cells, and observed that the integrity of confluent culture is disrupted and cell growth and migration rates are reduced in the presence of serum collected from scald burn injury rats (SRS) (6). To identify gene products involved in mechanisms underlying these effects, we used the cDNA expression microarray analysis and found that genes whose expression was affected by SRS in IEC-6 cells were primarily associated with cell shape, growth and death, stress-response, protein turnover and transport of water and electrolytes. These data demonstrate that a burn-induced circulating factor(s) modulates expression of genes, which may affect intestinal epithelial cell survival and function. Thus, these findings provide clues to the nature of molecular mechanisms potentially involved in multiple-organ malfunction, in particular the atrophy and enhanced permeability of gut mucosa, after burn injury.
Asunto(s)
Factores Biológicos/fisiología , Quemaduras/sangre , Regulación de la Expresión Génica , Intestinos/fisiología , Actinas/genética , Animales , Quemaduras/genética , Quemaduras/fisiopatología , Células Cultivadas , Células Epiteliales/patología , Células Epiteliales/fisiología , Intestinos/patología , Masculino , Análisis de Secuencia por Matrices de Oligonucleótidos , Ratas , Ratas Sprague-Dawley , Receptor de Insulina/genética , Inhibidor Tisular de Metaloproteinasa-2/genéticaRESUMEN
In experimental models of acute pancreatitis (AP), acinar cell death occurs by both necrosis and programmed cell death or apoptosis. Apoptosis is an active form of cell death associated with a tightly regulated expression of gene products that are either pro- or antiapoptotic. The aim of this study was to characterize pancreatic mRNA levels by Northern blotting analysis of apoptosis-associated genes used during the course of cerulein-induced AP in mice. Histone H3 mRNA levels were also examined as an indicator of cell proliferation. Acinar cell apoptosis was confirmed histologically. The findings show that AP modifies pancreatic mRNA levels of both pro- and antiapoptotic genes simultaneously. Pancreatic bclXL, bax, and p53 mRNA levels increased significantly in a temporal fashion during induction of AP. Pancreatic bcl-2 mRNA levels were unchanged during AP. Pancreatic mRNA levels of insulin-like growth factor-1 (IGF-1), a mitogen and cell survival factor, and its receptor (IGF-1R) also increased in a temporal fashion during induction of AP. In summary, this study indicates that acinar cell death during cerulein-induced AP in mice can occur by the apoptotic pathway. Since factors promoting and antagonistic for cell survival are activated simultaneously, regulation of acinar cell survival appears complex and dynamic during AP.
Asunto(s)
Apoptosis/genética , Supervivencia Celular/genética , Pancreatitis/genética , Enfermedad Aguda , Amilasas/sangre , Animales , Northern Blotting , Western Blotting , Ceruletida , Femenino , Genes p53/genética , Histonas/genética , Factor I del Crecimiento Similar a la Insulina/genética , Ratones , Pancreatitis/inducido químicamente , Pancreatitis/patología , Proteínas Proto-Oncogénicas/genética , Proteínas Proto-Oncogénicas c-bcl-2/genética , ARN Mensajero/análisis , Proteína X Asociada a bcl-2RESUMEN
In humans, decreased intestinal motility, compromised nutritional status and increased risk of colon cancer are commonly associated with aging. Here, we used the cDNA microarray analysis to detect age-associated changes in duodenal and colonic gene expression in male Fischer 344 rats. The primary finding of this study is that the magnitude and direction of age-associated changes in gene expression differs in the colon and duodenum. In the colon, 56 genes showed altered expression, whereas expression of only 25 genes was altered in the duodenum. The magnitude of change was greater in the colon than in the duodenum. The direction of change also differed; in the aged colon, expression of 51 genes increased and only five genes decreased. In contrast, in the aged duodenum, only seven genes increased, whereas 18 genes decreased in expression. In the duodenum of aged rats, expression of genes involved in ATP-generating pathways is decreased. In contrast, in the colon of aged rats, expression of genes involved in energy generating pathways and in lipid oxidation is increased. In addition, in the aging colon, an increased expression of genes that show an aberrant regulation in colon cancer, including CD44, ras, and maspin is observed. Collectively, these findings provide clues to molecular events that may be related to compromised intestinal function and the high incidence of colon cancer in the aged population.
Asunto(s)
Envejecimiento/genética , Colon/metabolismo , Duodeno/metabolismo , Expresión Génica , Lípidos/genética , Proteínas/genética , ARN/análisis , Animales , Northern Blotting , Colon/citología , ADN Complementario/análisis , Duodeno/citología , Marcadores Genéticos , Metabolismo de los Lípidos , Masculino , Proteínas/metabolismo , Ratas , Ratas Endogámicas F344 , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
We examined the effects of thermal injury on intestinal epithelial cell proliferation and death. We recorded histologically identifiable mitotic and apoptotic crypt cells in relation to cell position after a 60% full thickness cutaneous thermal injury in the rat. The injury significantly reduced mitosis (0.53 +/- 0.11 vs. 1. 50 +/- 0.70, P < 0.05) at cell positions 4-6, stem cells, 6 h after injury. A similar reduction in mitosis (1.13 +/- 0.59 vs. 3.50 +/- 0. 80, P < 0.05) was observed at higher cell positions 7-9 12 h after injury, indicating a positional cell shift. In addition, a significant increase in the number of apoptotic bodies occurred at cell positions 7-9 (2.32 +/- 0.87 vs. 0.13 +/- 0.22, P < 0.05) and 10-12 (2.2 +/- 0.12 vs. 0.00, P < 0.05) 6 h after injury. Thermal injury-induced alterations in mitotic and apoptotic activities were transient since crypts recovered with a moderate increase in mitotic activity 24 h after injury. In control and thermal-injury rats 24 h after injury, crypt cell mitosis and apoptosis did not differ significantly. This demonstrates that cutaneous thermal injury causes a transient suppression of mitosis as well as induction of apoptosis in a cell position-dependent manner in the small intestinal crypt.
Asunto(s)
Apoptosis/fisiología , Quemaduras/patología , Intestino Delgado/lesiones , Intestino Delgado/patología , Animales , Recuento de Células , División Celular/fisiología , Etiquetado Corte-Fin in Situ , Mucosa Intestinal/lesiones , Mucosa Intestinal/patología , Masculino , Mitosis/fisiología , Ratas , Ratas Sprague-DawleyRESUMEN
Chromogranin A (CgA) is a glycoprotein present in secretory granules of endocrine cells. In the parathyroid, it is costored and cosecreted with parathormone (PTH) in response to hypocalcemia. CgA is the precursor of several bioactive peptides including pancreastatin and betagranin. Parastatin (PARA, pCgA(347-419)) is a novel peptide that we generated in vitro by enzymatic digestion of pCgA. In vitro, it inhibits low Ca(2+)-stimulated parathyroid secretion. Full activity resides in its first 19 residues. In order to determine if PARA or PARA-derived peptides are natural products of the parathyroid, we generated an antiserum directed against pCgA(347-359) corresponding to the bioactive N-terminal sequence of pPARA (pPARA(1-13) antiserum), and developed a specific radioimmunoassay that we used in conjunction with various chromatographic separations. We identified small peptides carrying the pPARA(1-13) immunoactivity in extracts and secretion medium of porcine parathyroid glands. Continuous and pulse-chase radiolabeling studies, along with immunoprecipitation using PARA(1-13) antiserum demonstrate that a newly-synthesized PARA-related peptide fraction with a Mr of 11 kDa is secreted by the parathyroid cells and accumulates in the secretion medium. Edman degradation of the 11 kDa PARA-related peptide band by Edman degradation yielded three major N-terminal sequences: S-K-M-D-R-L-A-K-E-L-(residues 313-322), D-R-L-A-K-E-L-T-A-E-(residues 316-325), and A-K-E-L-T-A-E-K-R-L-(residues 319-329), in a molar ratio of approximately 1:2:1. The peptide bonds required to be cleaved to yield these peptides, Trp-Ser, Met-Asp and Leu-Ala, suggest that a chymotrypsin-like endopeptidase participated in their formation. The molecular size and the results of amino acid compositional analysis, indicate that the C-termini of these peptides extended variably to residues 384-401 of pCgA. These results demonstrate that processing of CgA by the parathyroid gland generates bioactive PARA-related peptides that could affect the gland's secretory activity.
Asunto(s)
Cromograninas/metabolismo , Glándulas Paratiroides/metabolismo , Hormona Paratiroidea/metabolismo , Fragmentos de Péptidos/metabolismo , Procesamiento Proteico-Postraduccional , Secuencia de Aminoácidos , Animales , Bovinos , Cromogranina A , Técnicas In Vitro , Datos de Secuencia Molecular , Radioinmunoensayo , PorcinosRESUMEN
The ubiquitous and persistent nature of polychlorinated aromatic hydrocarbons (PCAHs) in our environment and the risk of exposure to PCAHs have provoked concern over their potential toxicity. In humans, exposure to PCAHs is aimed chiefly at epithelial cells residing in the intestinal mucosa, because oral intake of contaminated food is a major source of PCAHs. The purpose of this study, therefore, was to examine the effects of chronic exposure to various PCAHs [i.e. 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,4,7,8-pentachlorodibenzofuran (PeCDF), 3,3',4,4',5-pentachlorobiphenyl (PCB-126), and 2,2'4,4'5,5'-hexachlorobiphenyl (PCB-153)], given alone or as mixtures, on intestinal cholecystokinin (CCK) peptide and messenger RNA levels. We show that chronic PCAH treatment significantly lowers intestinal levels of stored CCK peptide. Intestinal CCK messenger RNA levels are not affected. In addition, 3,3',4,4',5-pentachlorobiphenyl treatment increased intestinal insulin-like growth factor-binding protein-3 levels in a dose-related manner. Acute 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment of intestinal CCK cells lowered levels of CCK-processing enzymes (i.e. prohormone convertase-1 and -2). Together, these data indicate that PCAHs may decrease intestinal levels of stored CCK peptide by affecting the intestinal insulin-like growth factor system and CCK processing.
Asunto(s)
Colecistoquinina/metabolismo , Hidrocarburos Aromáticos/farmacología , Hidrocarburos Clorados/farmacología , Mucosa Intestinal/metabolismo , Intestinos/efectos de los fármacos , Animales , Ácido Aspártico Endopeptidasas/metabolismo , Benzofuranos/farmacología , Línea Celular , Colecistoquinina/genética , Cromogranina A , Cromograninas/metabolismo , Duodeno/efectos de los fármacos , Duodeno/metabolismo , Femenino , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/metabolismo , Ratones , Bifenilos Policlorados/farmacología , Dibenzodioxinas Policloradas/farmacología , Proproteína Convertasa 2 , Proproteína Convertasas , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Subtilisinas/metabolismoRESUMEN
The purpose of this study was to characterize the effects of aging on colonic messenger ribonucleic acid (mRNA) and protein levels of genes involved in the regulation of cell proliferation and apoptosis, and epithelial morphology in male Fischer 344 rats. Our study shows that, with aging, colonic expression of insulin-like growth factor-1 (IGF-1) and IGF-binding protein-3 (IGFBP-3) is significantly increased and decreased, respectively. Colonic Bax protein levels are increased significantly with aging. Immunohistochemical localization of Bax protein shows a greatly increased expression in colonic crypts, especially in the upper portion of crypts. p53 expression is unchanged with aging. No significant change in proliferation of colonic crypt cells is observed by bromodeoxyuridine (BrdU) labeling, although the increased colonic expression of IGF-1 and the decreased expression of IGFBP-3 with aging may result in an increased colonic IGF-1 bioactivity. The age-related changes in Bax and IGFBP-3 appear to be independent of p53. The finding of an unchanged colonic epithelium with aging in the face of a greatly increased Bax protein levels may suggest that the elevated Bax protein levels function to render colonic epithelial cells more sensitive to apoptotic stimuli.
Asunto(s)
Envejecimiento/genética , Colon/citología , Expresión Génica , Proteínas Proto-Oncogénicas c-bcl-2 , Animales , Apoptosis/genética , División Celular/genética , Colon/metabolismo , Células Epiteliales/citología , Células Epiteliales/metabolismo , Genes bcl-2 , Genes p53 , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/genética , Factor I del Crecimiento Similar a la Insulina/genética , Masculino , Proteínas Proto-Oncogénicas/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Ratas Endogámicas F344 , Proteína X Asociada a bcl-2RESUMEN
BACKGROUND: Parenterally nourished preterm infants commonly receive minimal enteral feedings, the aim being to enhance intestinal function. Whether this regimen increases intestinal growth has not been established. OBJECTIVE: Our objective was to determine the minimal enteral nutrient intakes necessary to stimulate and to normalize neonatal intestinal growth. METHODS: Intestinal growth and cell proliferation were quantified in neonatal pigs given equal amounts of an elemental nutrient solution for 7 d. Different groups (n = 5-7 per group) received 0%, 10%, 20%, 40%, 60%, 80%, or 100% of total nutrient intake enterally, with the remainder given parenterally. RESULTS: In the jejunum, wet weight, protein mass, and villus height were significantly greater at enteral intakes >40%. Stimulation of ileal protein mass required a higher enteral intake (60%). In both segments, abrupt increases in DNA mass, crypt depth, ornithine decarboxylase activity, and crypt cells in S-phase occurred between enteral intakes of 40% and 60%. Circulating concentrations of glucagon-like peptide-2 and peptide YY, but not gastrin, increased significantly between enteral intakes of 40% and 60% and closely paralleled indexes of cell proliferation. CONCLUSIONS: The minimal enteral nutrient intake necessary to increase mucosal mass was 40% of total nutrient intake, whereas 60% enteral nutrition was necessary to sustain normal mucosal proliferation and growth. Our results imply that providing <40% of the total nutrient intake enterally does not have significant intestinal trophic effects.
Asunto(s)
Animales Recién Nacidos/crecimiento & desarrollo , Nutrición Enteral , Intestinos/crecimiento & desarrollo , Necesidades Nutricionales , Animales , División Celular , ADN/análisis , Alimentos Formulados , Gastrinas/sangre , Péptido 2 Similar al Glucagón , Péptidos Similares al Glucagón , Íleon/crecimiento & desarrollo , Yeyuno/crecimiento & desarrollo , Tamaño de los Órganos , Péptido YY/sangre , Péptidos/sangre , Proteínas/análisis , Porcinos , Aumento de PesoRESUMEN
The purpose of this study was to determine the effects of aging and caloric restriction (CR) on insulin-like growth factor-I (IGF-I), IGF-I receptor (IGF-IR), IGF-binding protein-3 (IGFBP-3) and IGFBP-4 expression in the stomach and colon of male Fischer 344 rats. Stomach and colonic RNA were prepared from ad libitum (AL) fed or long-term CR rats. Stomach IGF-I, IGFBP-3 and IGFBP-4 mRNA levels increased significantly (P
Asunto(s)
Envejecimiento/fisiología , Colon/metabolismo , Mucosa Gástrica/metabolismo , Proteína 3 de Unión a Factor de Crecimiento Similar a la Insulina/genética , Proteína 4 de Unión a Factor de Crecimiento Similar a la Insulina/genética , Factor I del Crecimiento Similar a la Insulina/genética , Receptor IGF Tipo 1/genética , Envejecimiento/metabolismo , Animales , Ingestión de Energía , Expresión Génica , Masculino , ARN Mensajero , Ratas , Ratas Endogámicas F344RESUMEN
The purpose of this study was to test the hypothesis that the endoprotease, prohormone convertase-1 (PC-1), is involved in the processing of the precursor protein chromogranin A (CGA) to a smaller peptide called pancreastatin (PST). A human pancreatic carcinoid cell line (BON) that expresses PC-1, CGA and PST was stably transfected with antisense PC-1 mRNA. BON cells expressing antisense PC-1 mRNA showed nearly complete abolishment of PC-1 protein (approximately 95% reduction) and an 80% reduction in cell content of PST immunoreactivity (PST-IR) as assessed by high-performance liquid chromatography in combination with measurement of PST-IR. These findings indicate that PC-1 is essential for processing CGA to PST.
Asunto(s)
Ácido Aspártico Endopeptidasas/fisiología , Cromograninas/metabolismo , Hormonas Pancreáticas/metabolismo , Ácido Aspártico Endopeptidasas/genética , Tumor Carcinoide/enzimología , Tumor Carcinoide/metabolismo , Cromatografía Líquida de Alta Presión , Cromogranina A , Humanos , Hormonas Pancreáticas/biosíntesis , Neoplasias Pancreáticas/enzimología , Neoplasias Pancreáticas/metabolismo , Proproteína Convertasas , ARN Mensajero/metabolismo , Transfección , Células Tumorales CultivadasRESUMEN
In humans, cerebral hypoxia is a common component of severe brain insults, including trauma, stroke, and perinatal asphyxia. Oxidative stress and free radicals incidental to cerebral hypoxia are implicated in damaging macromolecules, leading to collapse of cellular homeostasis and cell death. Neuronal DNA damage, as a direct measurable event, has not been addressed in cerebral hypoxia. Here, we measured hypoxia-induced damage and repair in nuclear and mitochondrial DNA in rat hippocampus and cortex. Two highly sensitive quantitative polymerase chain reaction (QPCR) assays were used to measure DNA damage. One assay measures the integrity of the entire mitochondrial genome and the other the integrity of nuclear DNA. The latter is a novel assay, developed in our laboratory, which utilizes the high copy number of short interspersed DNA elements (SINEs) residing in introns and untranslated regions of mammalian genes. A unique feature of the SINE-mediated QPCR is its ability to amplify simultaneously long random segments of DNA. Consequently, the SINE assay offers sufficient sensitivity for detecting DNA damage at levels that are compatible with the cellular capacity for DNA repair, and are likely to be consistent with cellular survival and therefore adequate for studying the DNA damage response in the brain. In rats, we found that exposure to an atmosphere of 4% oxygen for 30 min resulted in induction of DNA damage in nuclear and to a greater extent, in mitochondrial DNA. Following a 3-hr recovery period in ambient air, dissimilar repair kinetics for nuclear and mitochondrial DNA were measured.
Asunto(s)
Encéfalo/metabolismo , Núcleo Celular/genética , Daño del ADN , ADN Mitocondrial/genética , Hipoxia Encefálica/genética , Animales , Encéfalo/ultraestructura , Reparación del ADN , Reacción en Cadena de la Polimerasa/métodos , RatasRESUMEN
Gastrin-releasing peptide (GRP) and its amphibian homolog, bombesin, are potent secretogogues in mammals. We determined the roles of intracellular free Ca(2+) ([Ca(2+)](i)), protein kinase C (PKC), and mitogen-activated protein kinases (MAPK) in GRP receptor (GRP-R)-regulated secretion. Bombesin induced either [Ca(2+)](i) oscillations or a biphasic elevation in [Ca(2+)](i). The biphasic response was associated with peptide secretion. Receptor-activated secretion was blocked by removal of extracellular Ca(2+), by chelation of [Ca(2+)](i), and by treatment with inhibitors of phospholipase C, conventional PKC isozymes, and MAPK kinase (MEK). Agonist-induced increases in [Ca(2+)](i) were also inhibited by dominant negative MEK-1 and the MEK inhibitor, PD89059, but not by an inhibitor of PKC. Direct activation of PKC by a phorbol ester activated MAPK and stimulated peptide secretion without a concomitant increase in [Ca(2+)](i). Inhibition of MEK blocked both bombesin- and phorbol 12-myristate 13-acetate-induced secretion. GRP-R-regulated secretion is initiated by an increase in [Ca(2+)](i); however, elevated [Ca(2+)](i) is insufficient to stimulate secretion in the absence of activation of PKC and the downstream MEK/MAPK pathways. We demonstrated that the activity of MEK is important for maintaining elevated [Ca(2+)](i) levels induced by GRP-R activation, suggesting that MEK may affect receptor-regulated secretion by modulating the activity of Ca(2+)-sensitive PKC.
Asunto(s)
Quinasa 1 de Quinasa de Quinasa MAP , Proteínas Quinasas/fisiología , Receptores de Bombesina/fisiología , Bombesina/farmacología , Calcio/metabolismo , Proteínas Quinasas Dependientes de Calcio-Calmodulina/fisiología , Flavonoides/farmacología , Humanos , Proteína Quinasa C/fisiología , Proteínas Serina-Treonina Quinasas/fisiología , Acetato de Tetradecanoilforbol/farmacologíaRESUMEN
Proliferation of the gastrointestinal mucosa is stimulated by the growth factors, insulin-like growth factor-I (IGF-I) and transforming growth factor-alpha (TGF-alpha), or the closely related epidermal growth factor (EGF), as well as the gastrointestinal hormones, gastrin, neurotensin (NT), and peptide YY (PYY). The stimulatory actions of these growth factors or gastrointestinal hormones on the gastrointestinal mucosa may be direct or mediated in part by gastrointestinal peptides or the growth factors, respectively. The purpose of these studies therefore was to examine the effects of IGF-I and TGF-alpha on stomach gastrin and intestinal NT and PYY gene expression [i.e. messenger RNA (mRNA), peptide levels] and secretion. Mice were given recombinant human IGF-I (3, 6 mg/kg BW/day x 14 days). Transgenic mice with the rat TGF-alpha gene linked to a metallothionein promoter were used as a model of chronic TGF-alpha excess. IGF-I and TGF-alpha did not affect gastrin gene expression. Steady-state intestinal NT and PYY mRNA and peptide levels were elevated in a dose-related manner by IGF. TGF-alpha also increased intestinal expression of NT and PYY peptide, but not mRNA levels. Basal serum levels of PYY were elevated by IGF-I and TGF-alpha. IGF-I and TGF-alpha did not increase intestinal chromogranin A (CGA) gene expression, a marker of endocrine cells, or the density of PYY-containing cells in the colon, indicating that the elevations in intestinal gut peptide gene expression by IGF-I and TGF-alpha are not due simply to an increased number of enteroendocrine cells. IV infusion of EGF also stimulated release of PYY in the dog. Together, these findings indicate that IGF-I and TGF-alpha may cause secretion of gut hormones and exert a major upregulatory influence on the regulation of intestinal peptide hormone homeostasis.
Asunto(s)
Factor I del Crecimiento Similar a la Insulina/farmacología , Mucosa Intestinal/metabolismo , Neurotensina/metabolismo , Péptido YY/metabolismo , Factor de Crecimiento Transformador alfa/farmacología , Animales , Cromogranina A , Cromograninas/genética , Cromograninas/metabolismo , Perros , Humanos , Factor I del Crecimiento Similar a la Insulina/genética , Ratones , Ratones Transgénicos/genética , Neurotensina/genética , Péptido YY/genética , ARN Mensajero/metabolismo , Ratas , Proteínas Recombinantes/farmacología , Factor de Crecimiento Transformador alfa/genéticaRESUMEN
The effects of a 60% body surface area thermal injury in rats on the morphology and proliferation of the epithelium of the small intestine and the in vitro effects of serum collected from scalded rats on intestinal epithelial cells were investigated. Scald injury caused significant reductions in duodenal villus width and crypt dimensions, villus enterocytes changed in shape from columnar to cuboidal, and the number of goblet cells decreased. The proportion of bromodeoxyuridine-labeled S phase cells in crypts was also diminished. In vitro, incubation of intestinal epithelial cells (IEC-6) with scalded rat serum (SRS) collected at either 12 or 24 h after injury caused a disruption in the integrity of the confluent culture and induced the appearance of large denuded areas. SRS also decreased DNA synthesis and delayed wound closure in an in vitro wound-healing model. The thermal injury-induced changes in intestinal mucosal morphology and epithelial cell growth characteristics described in this study may underlie, in part, the mechanism(s) involved in the diminished absorption of nutrients, increased intestinal permeability, and sepsis in patients with thermal injury.
Asunto(s)
Quemaduras/sangre , Intestino Delgado/patología , Intestino Delgado/fisiopatología , Animales , Fenómenos Fisiológicos Sanguíneos , División Celular/fisiología , Línea Celular , Movimiento Celular/fisiología , Mucosa Intestinal/patología , Masculino , Ratas , Ratas Sprague-DawleyRESUMEN
Effective clinical therapy to augment intestinal absorption of water and electrolytes does not exist; the gut hormone, peptide YY (PYY), is a potent proabsorptive agent in animal models. The purpose of our study was to evaluate the effects of two novel PYY analogs, BIM-43073D and BIM-43004C, on intestinal absorption. Dogs with ileal Thiry-Vella fistulae (TVF) were treated with either PYY, BIM-43073D, or BIM-43004C. Administration of BIM-43073D significantly increased water and sodium absorption over baseline and maintained this level of increased absorption for a longer duration than an equimolar dose of PYY. Administration of BIM-43004C significantly increased sodium and water absorption over baseline at a level equal to that of PYY. The novel PYY analogs, BIM-43073D and BIM-43004C, are effective proabsorptive agents with BIM-43073D producing more sustained effects than PYY. These compounds may be clinically useful in the treatment of gut malabsorption in conditions such as cholera, Crohn's disease, and the short-bowel syndrome.
Asunto(s)
Absorción Intestinal/efectos de los fármacos , Péptido YY/farmacología , Péptidos/farmacología , Animales , Perros , Femenino , Enfermedades del Íleon/tratamiento farmacológico , Enfermedades del Íleon/fisiopatología , Péptidos y Proteínas de Señalización Intercelular , Fístula Intestinal/tratamiento farmacológico , Fístula Intestinal/fisiopatología , Síndromes de Malabsorción/tratamiento farmacológico , Péptido YY/uso terapéutico , Péptidos/uso terapéutico , Equilibrio Hidroelectrolítico/efectos de los fármacosRESUMEN
An obese mouse model (Cpefat/Cpefat) that has hyperproinsulinemia and late onset obesity has been described. Cpefat/Cpefat mice have a missense mutation in carboxypeptidase E (CPE), a processing enzyme essential for production of biologically active endocrine and neuroendocrine peptides. We have reported previously that CPE activity was absent in the antrum of the stomach and that processing of progastrin to the amidated biologically active form of gastrin is reduced. Since gastrin is a major secretagogue for gastric acid secretion, the purpose of the present experiments was to examine gastric acid secretion in Cpefat/Cpefat mice. In addition, secretion of amidated gastrin in response to inhibition of acid secretion was tested in Cpefat/Cpefat. Both gastric acid and challenged gastrin secretion are reduced in Cpefat/Cpefat mice. We conclude that stomach CPE activity is essential for gastric secretory activity and for challenged gastrin release.
Asunto(s)
Carboxipeptidasas/deficiencia , Ácido Gástrico/metabolismo , Mucosa Gástrica/enzimología , Gastrinas/metabolismo , Mutación Missense , Obesidad/genética , Animales , Carboxipeptidasa H , Carboxipeptidasas/genética , Famotidina/farmacología , Mucosa Gástrica/efectos de los fármacos , Antagonistas de los Receptores H2 de la Histamina/farmacología , Ratones , Ratones Obesos , Obesidad/enzimología , Proinsulina/sangreRESUMEN
Gastrin-secreting tumors have been identified in ectopic locations including the ovary; the mechanisms regulating gastrin gene expression, its distribution, and signaling pathways in these ectopic tissues are not known. The purpose of our present study was to determine: (1) whether the gastrin gene and peptide could be detected in ovarian cancer cell lines, (2) if functional gastrin releasing peptide receptors (GRP-R) are present, and (3) whether gastrin gene expression is altered by GRP. Five ovarian cancer cell lines (SW626, OVCA 420, OVCA 429, OVCA 432, and OVCA 433) were analyzed. We identified gastrin gene and peptide expression in the SW626 cell line but not in the OVCA lines. SW626 cells express a functional GRP-R that is correctly coupled to the Ca2+ signaling pathway. Treatment of SW626 cells with bombesin, the amphibian equivalent of GRP, inhibited expression of the gastrin gene in a time- and dose-dependent fashion. The SW626 ovarian cancer cell line will provide a useful model to further define regulation and expression of both the gastrin gene and peptide in ectopic (nongastrointestinal) tissues.
Asunto(s)
Cistadenocarcinoma/genética , Gastrinas/genética , Regulación Neoplásica de la Expresión Génica , Neoplasias Ováricas/genética , Northern Blotting , Southern Blotting , Bombesina/farmacología , Cistadenocarcinoma/patología , Femenino , Gastrinas/biosíntesis , Humanos , Neoplasias Ováricas/patología , Reacción en Cadena de la Polimerasa , Radioinmunoensayo , Receptores de Bombesina/análisis , Receptores de Bombesina/efectos de los fármacos , Receptores de Bombesina/metabolismo , Células Tumorales CultivadasRESUMEN
The purpose of this study was to investigate the effects of activation of various second messenger signaling systems on gene expression (i.e. mRNA levels) of a peptide hormone processing enzyme called prohormone convertase-1 (PC-1, also called PC-3) in a human pancreatic carcinoid cell line (BON) that expresses several endocrine peptides (chromogranin A, pancreastatin, neurotensin). Pharmacologic activation of adenylate cyclase-cAMP, protein kinase-C and Ca2+ mobilization pathways increased PC-1 mRNA levels and neurotensin secretion. Elevations in PC-1 mRNA levels were dose and time-related. Secretagogue-induced cellular depletion of neurotensin was followed by a replenishment of cellular neurotensin stores and an upregulation of PC-1 mRNA levels. Together, these data indicate that PC-1 mRNA expression is increased with peptide secretion and coordinated with maintenance of cellular stores of peptides.
Asunto(s)
Ácido Aspártico Endopeptidasas/genética , ARN Mensajero/genética , ARN Mensajero/metabolismo , 8-Bromo Monofosfato de Adenosina Cíclica/farmacología , Adenilil Ciclasas/metabolismo , Calcimicina/farmacología , Calcio/metabolismo , Línea Celular , AMP Cíclico/metabolismo , Activación Enzimática/efectos de los fármacos , Expresión Génica , Humanos , Ionóforos/farmacología , Sistemas Neurosecretores/efectos de los fármacos , Sistemas Neurosecretores/fisiología , Neurotensina/metabolismo , Proproteína Convertasas , Proteína Quinasa C/metabolismo , Sistemas de Mensajero Secundario , Acetato de Tetradecanoilforbol/farmacología , Regulación hacia ArribaRESUMEN
A luminal cholecystokinin releasing factor (LCRF), has been purified from intestinal secretion and found to have a mass of 8136 daltons. The amino-terminal 41 residues have been sequenced. Previous studies showed that intraduodenal infusion of the synthetic amino-terminal 35 amino acid peptide, LCRF1-35 significantly stimulated pancreatic protein and fluid secretion in conscious rats, but the peptide did not stimulate amylase release from isolated, dispersed pancreatic acini. In the present study, several fragments of LCRF were synthesized and tested for CCK-releasing activity (pancreatic protein secretion) to determine whether shorter fragments of LCRF exhibit the characteristic biological activity of native LCRF and synthetic LCRF1-35. Compounds tested were LCRF1-41, LCRF1-35, LCRF1-65 and LCRF11-25. Of the fragments shorter than LCRF1-35, only LCRF11-25 but not LCRF1-6 had significant CCK releasing activity. LCRF1-41 was equivalent to LCRF1-35 in potency and efficacy. Intravenous and intraduodenal infusion of LCRF1-35 elicited nearly identical dose-response curves.