The Effects of Qualitative and Quantitative Protein Malnutrition on Cecal Microbiota in Wistar Rats with or without Neutrophil Suppression


Abstract: Gastrointestinal microbiota has been claimed to be affected by the diet consumed. In this study the effects of severe qualitative and quantitative protein malnutrition on cecal microbiota of male Wistar rats with or without neutrophil depletion were investigated. A total of 43 animals were divided randomly into 7 groups. Group I (control) was given a complete chow diet, groups II, III and IV received almost protein free (N-free) diet and groups V, VI and VII received a 20% gelatin containing diet for 35 days ad libitum. In addition, groups I, II and V were given physiologic saline, groups III and VI were given normal rabbit serum while groups IV and VII were given anti-rat neutrophil antibody containing rabbit serum (antineutrophil serum) by intraperitoneal route weekly. At the end of experiment, the animals were euthanized; the ceca were removed aseptically and total aerobe and anaerobe microorganisms, lactobacilli and Enterobacteriaceae were isolated from cecal contents. The evidences indicated that the growth of cecal aerobe microorganisms and lactobacilli was influenced by the quantity and quality of the dietary protein, while total anaerobes and Enterobacteriaceae remained unaffected. The count of cecal lactobacilli was decreased by protein malnutrition. The differences between the control group and both malnourished groups given SP were confirmed statistically (P < 0.0001). In addition, the comparisons among different malnourished groups showed that the mean count of lactobacilli in group III was significantly higher than that of groups II, IV, V, VI and VII (P < 0.05, P < 0.01, P < 0.05, P < 0.01 and P < 0.05, respectively). Also, for total aerobe microorganisms the differences between group IV and groups VI and VII and between group II and group VI were confirmed (P < 0.01, P < 0.05 and P < 0.05, respectively). We conclude that dietary protein could influence the cecal microbiota, and this effect could be modified by actual immune status of animals.

Keywords: Diet, qualitative and quantitative protein malnutrition, neutrophil suppression, cecal microbiota, rat

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