The effect of ileocecal valve removal in a model of short bowel syndrome / Efeito da remoção da válvula ileocecal em modelo de síndrome do intestino curto

ABSTRACT Background : Short bowel syndrome is a harmful condition that needs experimental research. Aim: To assess the impact of the ileocecal valve removal in a model of short bowel syndrome, in order to investigate the evolution of the colon under this circumstance. Method: Fifteen Wistar rats were equitable divided into: Control (Sham), Group I (70% enterectomy preserving ileocecal valve) and Group II (70% enterectomy excluding ileocecal valve). After enterectomy was performed jejunoileal or jejunocecal anastomosis and sacrificed the animals on 30th postoperative day for histomorphometric study of the colon. During this period, was observed the clinical evolution of the animals weekly including body weight measurement. Results: Group I and II presented progressive loss of weight. In Group I was observed diarrhea, perineal hyperemia and purple color of the colon during autopsy. Histomorphometry assay showed hypertrophy and hyperplasia of colon mucosa in Group I. In Group II the colon wall was thicker due to hypertrophy and muscular hyperplasia, and in mucosa vascular proliferation and inflammatory infiltrate were intense. Conclusion : This short bowel syndrome model is relevant and achieve 100% of survival. Animal's weight loss was not altered by the presence or exclusion of the ileocecal valve. Animals with 70% of small bowel removal and presence of the ileocecal valve attained a better clinical evolution and histological colon adaptation than those without ileocecal valve.

RESUMO Racional: Síndrome do intestino curto é condição clínica crítica e que precisa de pesquisa experimental. Objetivo: Avaliar o impacto da remoção da válvula ileocecal em um modelo de síndrome do intestino curto para investigar o comportamento do cólon nesta circunstância. Método: Quinze ratos Wistar foram divididos em três grupos de cinco: Controle (Sham), grupo I (enterectomia de 70% com preservação da válvula ileocecal), e grupo II (70% enterectomia de 70% excluindo a válvula ileocecal). Após a enterectomia foi restabelecido o trânsito com anastomose jejunoileal no grupo I e jejunocecal no grupo II. Os animais foram sacrificados no 30º dia do pós-operatório para histomorfometria do cólon. Durante este período, observou-se a evolução clínica semanal, incluindo a medição do peso corporal. Resultados: Grupos I e II apresentaram perda progressiva de peso. No grupo I houve diarreia, períneo hiperemiado e cor violácea do cólon durante a autópsia. A histomorfometria mostrou hipertrofia e hiperplasia da mucosa do cólon no grupo I. No grupo II a parede do cólon estava mais espessa devido à hipertrofia e hiperplasia das camadas muscular e mucosa onde a proliferação vascular e infiltração inflamatória foi intensa. Conclusão: Este modelo é factível e atingiu 100% de sobrevida. A perda de peso não foi alterada pela presença ou exclusão da válvula ileocecal. Animais com remoção de 70% do intestino delgado e presença da válvula ileocecal apresentaram melhor evolução clínica e adaptação histológica do cólon que os sem válvula ileocecal.

Botulinum toxin as a treatment for short bowel syndrome in rats

Abstract Purpose: The denervation of the intestine with benzalkonium chloride (BAC) reduces mortality and improves weight gain in rats with short bowel syndrome (SBS). Nevertheless, translating these promising findings from bench to bedside is not feasible because BAC promotes peritonitis and irreversible denervation which may be followed by an uncontrolled dilatation of the viscera. The use of botulinum toxin (BT) instead of BAC to achieve the denervation of the remaining small intestine in SBS could be an interesting option because it leads to a mild and transient denervation of the intestine. Methods: Here we evaluated the effects of the ileal denervation with BT in rats with SBS by verifying the body weight variation and intestinal morphological parameters. Four groups with 6 animals each were submitted to enterectomy with an ileal injection of saline (group E) or BT (group EBT). Control groups were submitted to simulated surgery with an ileal injection of BT (group BT) or saline (group C - control). Results: We observed that the treatment of the remaining ileum with BT completely reversed the weight loss associated to extensive small bowel resection. Conclusion: This may provide a new promising approach to the surgical treatment of SBS.

Are there differences in the growth adaptation processes of growing and mature organism models of short bowel syndrome?

OBJECTIVES: The purpose of this study was to present an experimental model of short bowel syndrome (SBS) in weaning rats and to compare the adaptative mechanisms of the remaining bowel in weaning rats and adult animals by means of morphometric, histologic and molecular methods. METHODS: Twenty-four weaning rats were divided into 3 groups of 8 animals, one control group and two short bowel groups (euthanasia after 4 and 21 days), and were compared with similar adult groups. Morphometric evaluations of the animals and histopathological and molecular studies of the remaining bowel were performed. RESULTS: The weight of young rats increased after enterectomy, whereas that of adult rats decreased after enterectomy (p<0.0001). The ratio of intestinal length/body weight was significantly higher in weaning rats than in adults (p<0.002), showing that intestinal growth was more intense in weaning rats. Intestinal resection promoted increased thickness of the small bowel lamina propria (p=0.001) and reduced thickness of the colon lamina propria (p=0.04) in weaning rats relative to those in adults. In addition, intestinal resection promoted increased expression of the Bcl-xl gene (antiapoptotic) in adult animals compared with that in weaning rats (p=0.001). CONCLUSION: Morphometric, histological and molecular differences were shown in the adaptation processes of growing and mature organisms.

Efeitos da desnervação intrínseca do jejuno após enterectomia extensa na síndrome do intestino curto em ratos / Effects of intrinsic denervation of the jejunum after extensive enterectomy in the rat bowel syndrome

OBJETIVO: Investigar em ratos Wistar as respostas adaptativas da mucosa em conseqüência da desnervação intrínseca do jejuno após ressecção intestinal extensa. MÉTODOS: Utilizaram-se 30 ratos distribuídos em três grupos segundo o procedimento realizado: C (controle), R (ressecção intestinal) e D (ressecção intestinal e desnervação intrínseca do jejuno). Posteriormente foi avaliado o ganho de peso e realizado estudos morfométrico da mucosa intestinal. RESULTADOS: Os animais do grupo D apresentaram ganho ponderal consideravelmente maior do que os do grupo R (D=312,2±21g e R=196,7±36,2g). A contagem neuronal mostrou diminuição na população de neurônios mientéricos no grupo D (344,8±34,8 neurônios/mm de jejuno) em relação aos outros grupos (R=909,0±55,5 e C=898,5±73,3). A área do epitélio da mucosa jejunal foi maior no grupo D (10,8±4,3mm²) em comparação aos grupos R (7,3±3,9mm²) e C (5,8±3,0mm²). O índice de proliferação celular epitelial da mucosa foi maior no grupo D (48,7 por cento), em relação aos grupos R (31,9 por cento) e C (23,6 por cento). CONCLUSÕES: O modelo experimental mostrou-se eficaz em melhorar o ganho ponderal dos animais submetidos à ressecção intestinal extensa, provocando intensificação da resposta hiperplásica da mucosa, a qual provavelmente levou a aumento da superfície de absorção de nutrientes. Abrem-se boas perspectivas para novas abordagens cirúrgicas para a síndrome do intestino curto.