The effects of food restriction on some biochemical parameters and certain bacterial groups in the cecum in Sprague Dawley rats

Abstract

Objective: Moderate food restriction, such as a 20-40% reduction of the ad libitum intake without causing malnutrition, delays or prevents morphological and functional changes related to aging and overnutrition. This study was performed to evaluate the effects of moderate to severe food restriction (20%, 40%, and 60% of ad libitum intake) for 28 days on some bacterial groups in the cecum and certain biochemical variables in male Sprague Dawley rats. Materials and methods: One group was allowed free access to food (control), while the others were given food restricted to 20%, 40%, and 60% of the ad libitum consumption for 28 days. At the end of the experiment control and food-restricted animals were sacrificed and cecum weight, pH of cecal contents, and counts of total anaerobes, total aerobes, lactobacilli, and coliform bacteria in cecal contents were determined. Metabolic effects of food restriction were evaluated by analyzing some biochemical parameters in plasma and serum. Results : The effect of 60% restriction was severe; three animals died before the 28th day of experiment in this group. In general, biochemical variables did not change in 20% and 40% food-restricted groups. Although lactobacilli counts of the 20% and 40% restricted groups were significantly increased when compared with the 60% restricted group, none of the three groups were differed from the control group. Furthermore, the total aerobe bacteria counts of the 20% restricted group were significantly lower than those of the 60% restricted group. Conclusion: The results of this study suggest that restriction of food by 20% and 40% may affect cecal microbiota beneficially without causing considerable changes in the metabolism of the host, while 60% restriction causes dietary stress. Key words: food restriction, starvation, malnutrition, rat, cecal microbiota, biochemical variables