No / The neuromedin U (NMU) receptors, NMU1 and NMU2, are expressed in the gut but their functions are unclear. This study explores the role of NMU in gastrointestinal motility. Experimental approach: The effects of NMU were examined in the forestomach and colon isolated from NMU2R wild-type and NMU2R-/- (knockout) mice, looking for changes in muscle tension and in nerve-mediated responses evoked by electrical field stimulation (EFS), and in models of peristalsis in mouse colon and faecal pellet transit in guinea-pig colon. Key results: In the mouse forestomach, NMU (1 nM-10 ¿M) concentration-dependently induced muscle contraction, in the presence of tetrodotoxin and atropine, in preparations from both wild-type and NMU2R-/- mice (pEC50: 7.9, 7.6, Emax: 0.26, 0.20g tension, respectively, n=8 each concentration). The same concentrations of NMU had no consistent effects on the responses to EFS (n=8). In the mouse colon, NMU (0.1 nM-1 ¿M) had no significant effect on baseline muscle tension (n=8), but concentration-dependently potentiated EFS-evoked contractions in preparations from both wild-type and NMU2R-/- mice, pEC50: 8.1, 7.8, Emax: 24%, 21%, respectively, n=6-11. NMU (0.01 nM-0.1 ¿M, n=5-7) concentration-dependently decreased the interval between waves of peristalsis in the mouse colon (pEC50: 8.8) and increased the rate at which a faecal pellet moved along the guinea-pig colon. Conclusions and implications: These results demonstrate that NMU exerts colon-specific, nerve-mediated, prokinetic activity, via a pathway involving activation of NMU1 receptors. This suggests that this receptor may represent a molecular target for the treatment of intestinal motility disorders.

Serotonin (5-hydroxytryptamine, 5-HT) has long been associated with the vertebrate gut and is an important neuromodulator of crustacean foregut. This dissertation presents evidence that 5-HT initiated peristalsis in crayfish hindgut and enhanced the power of contractions in caudal regions of the hindgut. 5-HT receptor immunoreactivity studies showed that the two identified crustacean 5-HT receptors, 5-HT1α and 5-HT2β are present on the hindgut in different and distinctive patterns. 5-HT immunoreactivity (5-HT-ir) studies revealed that the fibers from central neurons found on the hindgut showed a broad range of 5-HT-ir intensity, which led to the hypothesis that they borrowed 5-HT. This hypothesis was tested by first determining that the HGNs can take up 5-HT through a serotonin transporter and that uptake can be blocked by a serotonin reuptake inhibitor. Second, synthesis was tested by superfusing tryptophan and using 5-HT-ir to determine the presence of 5-HT. No constitutive 5-HT synthesis occurred under these conditions. Superfusion of the intermediate product of 5-HT synthesis, 5-hydroxytryptophan (5-HTP), did lead to 5-HT-ir. The HGNs can take up 5-HT but have only one of the synthetic enzymes. The lack of nearby sources for 5-HT led to the hypothesis that hormonally supplied 5-HT may be the source for 5-HT in the HGNs. High performance liquid chromatography measurements of 5-HT and 5-HTP levels in tissue following injection of 5-HT into the hemolymph revealed that levels of 5-HT significantly increased in the terminal ganglion and hindgut, where the HGNs cell bodies and projections are respectively located. All other areas of the central nervous system, with the exception of the brain, also showed a significant increase in 5-HT levels. Injection of tryptophan produced a significant increase in 5-HTP levels in the brain. Quantitative 5-HT-ir indicated that feeding increased the intensity of 5-HT-ir in the HGNs. Feeding was determined to be a relevant stimulus to examine facultative synthesis of 5-HT. The enzyme that converts 5-HT to 5-HTP was blocked and 48 hrs after feeding 5-HTP-ir was used to indicate that facultative synthesis did not occur. At the same time, 5-HT-ir was used to indicate that uptake of 5-HT by the HGNs more likely occurred.

Includes bibliography / 135 leaves, 7 leaves of plates : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, 1986

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Isovaleric Acid (IVA) is a 5-carbon branched chain fatty acid present in fermented foods and produced by the fermentation of leucine by colonic bacteria. IVA activates G-protein coupled receptors such as FFAR2, FFAR3, and OR51E1 known to be expressed on enteric neurons and enteroendocrine cells. We previously reported that the shorter, straight chain fatty acids acetate, propionate and butyrate, differentially affect colonic propulsion; however, the effect of branched chain fatty acids on gastrointestinal motility is unknown. We hypothesize that IVA relaxes smooth muscle in a cAMP/PKA dependent manner by direct action on smooth muscle cells. IVA will also decrease peristalsis and encourage retention of luminal contents. This thesis investigates the effect of IVA on smooth muscle tension and peristaltic activity in isolated colon and individual smooth muscle cells. Colon segments from C57BL/6J mice were placed in a longitudinal orientation in organ baths in Krebs buffer and fastened to force transducers. Segments were contracted with 10 μM acetylcholine (ACh) and the effects of IVA at several concentrations were measured in the absence and presence of Nitric Oxide Synthase inhibitor L-N-nitroarginine (L-NNA), neuronal action potential inhibitor tetrodotoxin (TTX), and adenylate cyclase inhibitor SQ22536. To study individual live cells, mouse smooth muscle was isolated from colon, suspended in smooth muscle buffer, and after contraction with ACh were relaxed with micromolar concentrations of IVA. For peristalsis studies, whole colonic segments isolated from C57BL/6J were catheterized and placed horizontally in organ baths with circulating Krebs buffer. The colon was clamped on the anal end, and a solution (5 μL per mm of colon length) of either Krebs buffer or 50 mM IVA was delivered from the oral end to the lumen. Video of the peristalsis was then analyzed for diameter, changes in diameter, velocity of diameter changes along the length of the colon, normalized to the anatomical changes in the proximal region. IVA in concentrations of 10 mM to 50 mM relaxed the ACh-induced contraction in a sigmoidal fashion. In separate studies, L-NNA nor TTX affected the ability of IVA to inhibit relaxation. SQ22536 inhibited IVA induced relaxation in longitudinal colon compared to vehicle control. In isolated cells, SQ22536 and PKA inhibitor H-89 inhibited IVA-induced relaxation. In peristalsis studies, 50 mM IVA in Krebs buffer changed the character of the peristaltic action by increasing proximal diameter, inhibiting contractions in the proximal end of the colon, and decreasing overall velocity of peristaltic contractions in the proximal region. The data indicate that the branched chain fatty acid IVA causes a concentration-dependent relaxation of colonic smooth muscle that is direct to the smooth muscle and independent of neuronal activity. This relaxation is cAMP/PKA dependent. In addition to the direct relaxation of smooth muscle, intraluminal IVA decreased overall colonic propulsive activity and encouraged retention of the luminal contents. We conclude that the ingestion and production of branched chain fatty acids could affect overall GI motility and is an area for study in dietary and therapeutic control of bowel activity.

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As células intersticiais de Cajal (CIC) têm sido estudadas como participante do peristaltismo em vários sistemas. Sua presença no trato geniturinário pode sustentar a importância dessas células na fisiopatologia da estenose da junção ureteropielica (JUP). O Objetivo desse estudo foi avaliar a densidade das CIC em pacientes adultos e no final da adolescência, portadores de estenose da JUP, submetidos à pieloplastia e verificar se há associação entre a densidade das CIC com os achados clínicos e de imagem pré e pós-operatórios, notadamente ultrassonografia e cintilografia renal. Foram estudados 23 pacientes com estenose da JUP, submetidos à pieloplastia desmembrada pela técnica videolaparoscópica na Divisão de Clínica Urológica do Departamento de Cirurgia do HCFMUSP, de forma consecutiva, pelo mesmo grupo de cirurgiões, no período entre fevereiro de 2011 a janeiro de 2012. Foi realizada análise imunohistoquímica para expressão do receptor de tirosina quinase (c-KIT) em todas as amostras das JUP e quantificada a densidade das CIC. Os pacientes foram acompanhados periodicamente para avaliação da resposta clínica e dos exames de imagem. Foi encontrado que a média de idade da amostra foi de 34,83 anos. Houve predomínio do gênero masculino (56,5%). O rim direito foi o mais acometido (56,5%). A hidronefrose grave foi identificada na maioria dos pacientes (52,2%). A média da função renal do rim acometido estimada pela cintilografia, pré e pós-operatória foi de respectivamente, 33,7 e 33,4%. Dos 23 pacientes, 20 apresentaram melhora do padrão cintilográfico de drenagem ureteral. Houve predomínio de pacientes que apresentavam alta densidade das CIC (52,2%). Houve significância estatística quando associado a densidade das CIC e a melhora do padrão ultrassonográfico (p= 0,032). Contudo, não houve associação entre a densidade das CIC e as outras variáveis clínicas ou de imagem. Pode-se concluir que a densidade das CIC pode ser um bom preditor da resposta ultrassonográfica pósoperatória em pacientes adultos com estenose da JUP submetidos à pieloplastia / The interstitial cells of Cajal (ICC) have been studied as peristalsis participating in various systems. Its presence in the genitourinary tract can sustain the importance of these cells in the pathophysiology of ureteropelvic junction obstruction (UPJO). The aim of this study was to evaluate the density of ICC in adults and in the late adolescence patients with UPJO, undergoing pyeloplasty and to check if there is association of changes in the ICC density with clinical findings, as well as pre and postoperative images, especially ultrasound and diuretic radioisotope renography. We selected 23 patients with UPJO, undergoing laparocopic dismembered pyeloplasty in the Urology Division of the HC-FMUSP Department of Surgery, consecutively, by the same group of surgeons in the period between February 2011 and January 2012. It was performed immunohistochemical analysis for tyrosine kinase receptor expression (c-KIT) in all samples of UPJO quantified the ICC density. The patients were followed up periodically to evaluate the clinical response and imaging. The average age of the sample was 34.83 years. There was a predominance of males (56.5%). The right kidney was the most affected (56.5%). Severe hydronephrosis was identified in most patients (52.2%). The average renal function affected estimated by diuretic radioisotope renography, pre and post-operative was respectively 33.7 and 33.4%. Of the 23 patients, 20 had an improvement on diuretic radioisotope renography pattern of ureteral drainage. There was a predominance of patients with high ICC density (52.2%). There was statistical significance when associated with ICC density and the improvement of ultrasonographic pattern (p = 0.032). However, there was no association between the ICC density and other clinical or imaging variables. It can be concluded that the density of the ICC maybe a good predictor of post-operative ultrasound response in adult patients with UPJO undergoing pyeloplasty