RESUMEN
OBJECTIVES: Severe congenital diarrhea occurs in approximately half of patients with Aristaless-Related Homeobox (ARX) null mutations. The cause of this diarrhea is unknown. In a mouse model of intestinal Arx deficiency, the prevalence of a subset of enteroendocrine cells is altered, leading to diarrhea. Because polyalanine expansions within the ARX protein are the most common mutations found in ARX-related disorders, we sought to characterize the enteroendocrine population in human tissue of an ARX mutation and in a mouse model of the corresponding polyalanine expansion (Arx). METHODS: Immunohistochemistry and quantitative real-time polymerase chain reaction were the primary modalities used to characterize the enteroendocrine populations. Daily weights were determined for the growth curves, and Oil-Red-O staining on stool and tissue identified neutral fats. RESULTS: An expansion of 7 alanines in the first polyalanine tract of both human ARX and mouse Arx altered enteroendocrine differentiation. In human tissue, cholecystokinin, glucagon-like peptide 1, and somatostatin populations were reduced, whereas the chromogranin A population was unchanged. In the mouse model, cholecystokinin and glucagon-like peptide 1 populations were also lost, although the somatostatin-expressing population was increased. The ARX protein was present in human tissue, whereas the Arx protein was degraded in the mouse intestine. CONCLUSIONS: ARX/Arx is required for the specification of a subset of enteroendocrine cells in both humans and mice. Owing to protein degradation, the Arx mouse recapitulates findings of the intestinal Arx null model, but is not able to further the study of the differential effects of the ARX protein on its transcriptional targets in the intestine.
Asunto(s)
Diarrea/genética , Enfermedades Duodenales/genética , Células Enteroendocrinas/fisiología , Proteínas de Homeodominio/genética , Seudoobstrucción Intestinal/genética , Péptidos/metabolismo , Factores de Transcripción/genética , Adolescente , Animales , Diferenciación Celular/genética , Colecistoquinina/análisis , Cromogranina A/análisis , Diarrea/patología , Modelos Animales de Enfermedad , Enfermedades Duodenales/patología , Duodeno/patología , Células Enteroendocrinas/química , Células Enteroendocrinas/patología , Insuficiencia de Crecimiento/genética , Femenino , Péptido 1 Similar al Glucagón/análisis , Proteínas de Homeodominio/análisis , Humanos , Seudoobstrucción Intestinal/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Mutagénesis Insercional , Somatostatina/análisis , Esteatorrea/genética , Factores de Transcripción/análisisRESUMEN
The exocrine pancreatic insufficiency (EPI) is a digestive disease caused by atrophy or inflammation of pancreatic acinar cells, resulting in nutrient malabsorption and clinical signs related to malnutrition. Three German Shepherds were presented at the Veterinary Hospital with background and clinical signs compatible with EPI, what was confirmed by routine laboratory testing. On physical examination, both presented bradyarrhythmias confirmed by computerized electrocardiogram. After therapy for EPI, the bradyarrhythmias were solved. The authors discuss the influence of the gastrointestinal hormone cholecystokinin, which can increase in pancreatic exocrine impairment, possibly reflecting a failure to provide feedback down-modulation of CCK release, causing cardiovascular effects, such as chronotropic and inotropic negative actions and promoting bradycardia.
A insuficiência pancreática exócrina (IPE) é uma enfermidade causada por atrofia ou inflamação das células acinares pancreáticas, resultando em má absorção de nutrientes e sinais clínicos relacionados à desnutrição. Três pastores alemães foram atendidos no Hospital Veterinário com histórico e sinais clínicos compatíveis com IPE, diagnosticada através de testes laboratoriais de rotina. Ao exame físico, os três animais apresentaram bradiarritmias, que foram confirmadas por eletrocardiograma computadorizado. Após o tratamento da IPE, houve normalização dos valores de freqüência cardíaca de todos os pacientes. Os autores discutem a influência do hormônio colecistoquinina, que pode estar elevado em casos de insuficiência pancreática exócrina e que, por sua vez, exerce efeitos cardiovasculares tais como cronotropismo e inotropismo negativos, promovendo desta forma a bradicardia destes pacientes.
Asunto(s)
Animales , Perros , Insuficiencia Pancreática Exocrina/veterinaria , Bradicardia/veterinaria , Colecistoquinina/análisis , Frecuencia Cardíaca , Electrocardiografía/veterinaria , Contracción MiocárdicaRESUMEN
The distribution of cholecystokinin-like immunoreactivity was studied in the central nervous system of the heteropteran insect Triatoma infestans using high-sensitivity immunocytochemistry. In the protocerebrum, CCK-IR somata were observed in the anteromedial, anterolateral and posterior cell-body layers. The neuropils displayed different densities of immunoreactive neurites. Few immunoreactive somata were found in the optic lobe in both the medial and lateral soma rinds, as well as in the proximal optic lobe. Immunoreactive fibers were present in the medulla and lobula neuropils. The sensory deutocerebrum contained a higher number of immunopositive perikarya than the antennal mechanosensory and motor center. The antennal lobe glomeruli displayed a moderate density of immunoreactive fibers. With regard to the subesophageal ganglion, numerous CCK-IR somata were found close to the root of the mandibular nerve; others were present in the soma rind of the remaining neuromeres. CCK-IR perikarya were present in both thoracic ganglia, with the abdominal neuromeres containing the highest number of positive somata. The neuropils of both ganglia showed moderate densities of immunopositive processes. The distribution of CCK-LI in somata and neuropils of central nervous system of T. infestans is widespread suggesting that a CCK-like peptide may act mainly as a neuromodulator in the integration of information from distinct sensory receptors.
Asunto(s)
Sistema Nervioso Central/química , Colecistoquinina/análisis , Triatoma/química , Animales , Sistema Nervioso Central/inmunología , Colecistoquinina/inmunología , Ganglios de Invertebrados/metabolismo , Inmunohistoquímica , Triatoma/citologíaRESUMEN
The ontogeny of the neurohormonal peptides vasoactive intestinal polypeptide (VIP), neurotensin (NT), substance P (SP), calcitonin gene-related peptide (CGRP), gastrin/cholecystokinin (GAS/CCK), and somatostatin (SOM) as well as serotonin (SER) and nitric oxide synthase (NOS) was investigated in the gastrointestinal tract of the urodele Ambystoma mexicanum, the axolotl, using immunohistochemical techniques. The first regulatory substances to appear were SP, SOM, and SER that could be immunohistochemically detected up from stage 1. At early stage 2, VIP immunoreactivity was observed infrequently in enteric nerve fibers. With the onset of external feeding at late stage 2, SP-immunoreactive (IR) and SER-IR endocrine cells and VIP-IR nerve fibers were present throughout the gastrointestinal tract. Furthermore, in the small intestine NT-IR and GAS/CCK-IR endocrine cells appeared. At stage 3, SER immunoreactivity was observed not only in endocrine cells but also in nerve fibers. CGRP-IR and SP-IR nerve fibers were detectable at stage 4 and stage 5, respectively. From stage 5 on, a minority of the CGRP immunoreactivity occurred in SP-IR nerve fibers. NOS immunoreactivity did not appear before stage 6 when it was found infrequently in nerve fibers. Thus, several phases of development can be distinguished: (1) at the yolk sac stages only few regulatory substances are present. (2) At the onset of external feeding, all endocrine cell types investigated were readily detectable. Thus, the onset of external feeding seems to trigger the development of the gastrointestinal endocrine system. (3) The endocrine cells are first found in the proximal part of the gastrointestinal tract and later in higher numbers in the distal parts. (4) The dually distributed neurohormonal peptides and SER first appear in endocrine cells and later additionally in nerve fibers. Thus, the nerve fibers likely set up the fine regulation of gastrointestinal blood flow and motility.
Asunto(s)
Ambystoma/crecimiento & desarrollo , Sistema Digestivo/crecimiento & desarrollo , Neuropéptidos/análisis , Sistemas Neurosecretores/crecimiento & desarrollo , Óxido Nítrico Sintasa/análisis , Serotonina/análisis , Ambystoma/metabolismo , Animales , Péptido Relacionado con Gen de Calcitonina/análisis , Colecistoquinina/análisis , Sistema Digestivo/química , Gastrinas/análisis , Inmunohistoquímica , Larva/crecimiento & desarrollo , Larva/metabolismo , Sistemas Neurosecretores/química , Neurotensina/análisis , Somatostatina/análisis , Sustancia P/análisis , Péptido Intestinal Vasoactivo/análisisRESUMEN
Cultured magnocellular neurons, isolated from adult rat supraoptic nuclei, were characterized by immunocytochemistry, using the avidin-biotin-peroxidase complex and antisera to vasopressin, oxytocin, galanin and cholecystokinin. Light microscope examination of the immunostained cultures revealed the presence of vasopressin- and oxytocin-like immunoreactivity, as well as neurons containing either galanin- or cholecystokinin-like immunoreactivity. In contrast, no significant galanin- or cholecystokinin-like immunoreactivity could be observed in freshly dispersed cells. Correlative scanning electron microscopical observations in the secondary electron imaging mode revealed that the stained neurons appeared significantly brighter than the unstained structures. Complementary observations with toad brain sections (preoptic area), immunostained for galanin, led to the same result. Considering previous results, it is suggested that the presence of galanin- and cholecystokinin-like immunoreactivity in the cultured neurons and its virtual absence in freshly dispersed cells is indicating a participation of these peptides in the regenerative processes taking place during culture. It is further concluded that the avidin-biotin-peroxidase method is suitable for correlative light and scanning electron microscopical studies of smooth surfaces and cultured cells.