The reduction of protein intake observed in old rats depends on the type of protein.
Previous experiments have shown in Lou/c/jall rats growing old a deleterious reduction of protein intake, which occurs earlier in males than in females. We previously showed that this decrease could not be attributed to a loss of regulation of protein intake with age. Present studies were designed to investigate if the age-related decrease of protein intake was dependent on the type of protein used. In a first sectional study, adult, middle and old-aged Lou/c/jall rats were submitted to a self-selection procedure. They were fed successively with casein, whey protein and fish flour as protein. In a second longitudinal study, self-selected males and females were tested each 4 months (at 3, 7, 11, 15, 19, 23 and 27 months of age) with only casein and whey protein as protein. In the two experiments, the type of dietary protein had an influence on the protein intake: when casein is offered, the well-established decrease in protein consumption was seen after 15 months of age in male groups. The introduction of whey protein induced maintenance of protein intake in old male groups at the level of female's protein intake. Moreover, young females showed an obvious preference for casein versus whey protein. This preference disappeared in old ages. These data showed that casein, even if it was an appropriate protein for young animals, could become inadequate for old animals and could result in a protein aversion in old rats. On the contrary, whey protein seemed to be a more appropriate protein than casein for old rats.
Nguema
Ghislaine Nzang
GN
Laboratoire de Neuroendocrinologie du Vieillissement, Complexe Scientifique des Cézeaux, Université Blaise Pascal, 24 rue des landais, 63177 Aubière Cedex, Clermont-Ferrand, France.
Grizard
Jean
J
Alliot
Josette
J
D000375:Aging / Q000502:physiology*; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002364:Caseins / Q000008:administration & dosage / Q000737:chemistry; D004044:Dietary Proteins / Q000008:administration & dosage*; D002149:Energy Intake; D005260:Female; D005518:Food Preferences / Q000502:physiology*; D008297:Male; D008894:Milk Proteins / Q000008:administration & dosage / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar; D000067816:Whey Proteins
D000596:Amino Acids; D002364:Caseins; D004044:Dietary Proteins; D008894:Milk Proteins; D000067816:Whey Proteins