Evaluation of gastrointestinal motility in awake rats: a learning exercise for undergraduate biomedical students

• Published in: Advances in physiology education 2009-12, Vol.33 (4), p.343-348
• Main Authors: Souza, M. A. N, Souza, M. H. L. P, Palheta, R. C., Jr, Cruz, P. R. M, Medeiros, B. A, Rola, F. H, Magalhaes, P. J. C, Troncon, L. E. A, Santos, A. A
• Format: Article
• Language: English
• Subjects: Anatomy & physiology; Animals; Biomedicine; Brazil; Comparative Analysis; Curricula; Education, Medical, Undergraduate - methods; Education, Medical, Undergraduate - standards; Experiential Learning; Foreign Countries; Gastrointestinal Motility - physiology; Graduate students; Graduate studies; Group Discussion; Humans; Insulin; Learning - physiology; Male; Medical Education; Medicine; Metabolism; Misconceptions; Physiology; Rats; Rats, Wistar; Rodents; Students, Medical; Undergraduate Students; Wakefulness - physiology
• ISSN: 1043-4046; 1522-1229
• DOI: 10.1152/advan.90176.2008

1 Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza; and 2 Department of Clinical Medicine, Ribeirão Preto School of Medicine, São Paulo University, São Paulo, Brazil Address for reprint requests and other correspondence: A. A. Santos, Laboratório Escola Prof. Luiz Capelo, Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Universidade Federal do Ceará, Caixa Postal 3157, Fortaleza 60.430-270, Brasil (e-mail: meno{at}ufc.br ). Abstract Current medical curricula devote scarce time for practical activities on digestive physiology, despite frequent misconceptions about dyspepsia and dysmotility phenomena. Thus, we designed a hands-on activity followed by a small-group discussion on gut motility. Male awake rats were randomly submitted to insulin, control, or hypertonic protocols. Insulin and control rats were gavage fed with 5% glucose solution, whereas hypertonic-fed rats were gavage fed with 50% glucose solution. Insulin treatment was performed 30 min before a meal. All meals (1.5 ml) contained an equal mass of phenol red dye. After 10, 15, or 20 min of meal gavage, rats were euthanized. Each subset consisted of six to eight rats. Dye recovery in the stomach and proximal, middle, and distal small intestine was measured by spectrophotometry, a safe and reliable method that can be performed by minimally trained students. In a separate group of rats, we used the same protocols except that the test meal contained 99m Tc as a marker. Compared with control, the hypertonic meal delayed gastric emptying and gastrointestinal transit, whereas insulinic hypoglycemia accelerated them. The session helped engage our undergraduate students in observing and analyzing gut motor behavior. In conclusion, the fractional dye retention test can be used as a teaching tool to strengthen the understanding of basic physiopathological features of gastrointestinal motility. Key words: duodenal brake; insulinic hypoglycemia; laboratory syllabus