[Dietary protein levels, and experimental inflammation in the rat]

The inflammatory response was studied using the contents (mucopolysaccharides and collagen of granuloma induced by turpentine in rats fed for 28 days after weaning), with semi-synthetic, isocaloric diets containing 0, 3.5, 9, 26 or 81% protein in the form of casein or with a laboratory chow. When the wet and dry weights and the water content of the granuloma are expressed in absolute values they show a substantial drop when the protein intake is low or excessive. If however the wet weight of the granuloma is expressed per 100 g of body weight, the differences become no longer significant, hence the importance of the nutritional state of the animal at the time of investigation. Using this test of the anti-inflammatory action of substances, it is necessary to differenciate between actual anti-inflammatory action and direct or secondary effects of the substance on the growth and behaviour of the animal. The levels of mucopolysaccharide drop in rats fed on hypo or hyper-proteinic diets, this would seem to be a sign of the decrease in the intensity of the anti-inflammatory response. What is more, the collagen itself undergoes modifications; there is a shift towards greater solubility of the fractions which would seem to indicate that a drop or a increase in the protein intake brings about a change in the processes of reticulation and maturation of the collagen; several hypothesis can be put forward to explain this phenomenon.