Mathematical correlation between villus height and the nutritional state in Sprague - Dawley rats

Three different experiments were carried out on growing male Sprague-Dawley rats. In the first experiment, dietary nitrogen was given in casein at four different protein values ranging from 5 to 16%. Rats were fed ad libitum for 21 days. In the second experiment, which lasted 17 days, animals were given three diets that differed in the molecular form of the nitrogen supply that is, proteins or peptides. The protein value (NX6.25) was 10% in each diet. In the third experiment, malnourished rats were refed diets with a protein value of 15% (NX6-25) for eight days. The dietary nitrogen was either in the form of protein, peptide, or amino acid. Body weight was recorded daily. At the end of each experiment the intestinal villus height was measured by light microscopy. Data were statistically analysed by Exner's coefficient. The results assessed the validity ofthe correlation between vilius height and gain in body weight. (Gut 1993; 34: 1066-1068) Unite de Nutrition, Genie Biologique et Sciences des Aliments, Departement Agroressources et Procedes Biologiques, Universite de Montpellier II, Montpellier, France J L Zambonino Infante J M Rouanet P Besanqon Correspondence to: Dr J M Rouanet, Unite de Nutrition, Case postale 030, GBSA, Universite de Montpellier II, Place Eugene Bataillon, 34095 Montpellier Cedex 05, France. Accepted for publication 28 October 1992 One of the important problems in nutrition is to determine how animals respond and adapt to a new diet. They must adapt to various nutritional conditions, particularly to the value, nature, and molecular form of the nitrogen in the diet to survive. The quality of nitrogen supply in foodstuffs is generally assessed by nutritional indices such as gain in body weight and how effectively protein is digested. Morphological measurements and enzyme activities carried out on intestinal mucosa are another good method of assessing dietary nitrogen quality. Changes in villus and microvillus height are relevant to such an adaptive response. i' Some authors' have emphasised the use of mucosal enzyme activities that is, those of disaccharidases and leucine aminopeptidase as indicators of dietary protein quality. On the other hand, assessment of morphological changes has more often been used in the diagnosis and assessment of intestinal pathology"'0 or in studies on intestinal development during fetal life." Finally, King et al,'2 have pointed out a trophic effect of the dietary nitrogen value on mucosal growth, triggering off an increase in villus height. The villus height depends upon two factors; firstly on cellular multiplication and differentiation from the crypts; and secondly on the migration of mature cells along the villus axis, accompanied by the cellular shedding from the apex. The regulation of these factors is widely considered to be the way in which the small intestine adapts to nutritional demands. 13-'7 Nevertheless it remains to be verified whether villus height is relevant to the previous dietary history that is, nitrogen supply quality and whether it depends on body weight at the time it is measured. This study aimed at working out a simple mathematical correlation between the villus height and gain in body weight in rats adapted to different experimental conditions.4819