Immunocompetence in relation to a heat-processed diet (Maillard reaction) in weanling rats

Abstract

~ ~~~~Diets containing unheated casein (CD; control) or a casein-glucose mixture (CGD) previously heated at 140" for 2 h were fed to two groups of young rats for 21 d. Differences in body weight, feed consumption, thymus and spleen growth, protein metabolism and in vivo immune response were then determined. For this last experiment, animals were inoculated with sheep erythrocytes (SRBC) on day 15 to provide an immunological challenge. No changes were seen in body weight, feed consumption or feed conversion ratios. Neither were significant differences found in spleen weight, protein content, DNA content, DNase (EC 3.1.4.6) activity or lymphocyte count, suggesting that spleen cell growth remained similar in all the animals studied. The CGD induced marked increases in thymus DNA content whilst the protein:DNA ratio became lower. Spleen RNA content was similar in all rats, but thymus RNA content was 29% lower in the CGD group, although this difference did not reach statistical significance. This fact might be a consequence of the low RNase (EC 2.7.7.16) activity and RNa9e:RNA ratios in the thymus glands of CGD-fed animals. Further, the number of splenic plasma cells secreting anti-SRBC antibodies (direct plaque-forming cells) was significantly decreased in the same group. It might be concluded that both diets are adequate for rat growth and that the differences observed in the thymus of CGD-fed rats may be directed towards preserving tissue function. Nevertheless, the CGD did cause immunological disturbances affecting the humoral immune response.

In vitro immuno-modulatory ability of tryptic caseinate hydrolysate affected by prior caseinate glycation using the Maillard reaction or transglutaminase

“…This means that any loss of these amino acids in GC-I hydrolysate or GC-II hydrolysates might lead to changed immune activities. The Maillard reaction is known to reduce nutritional properties of proteins (Martins, Jongen, & van Boekel, 2000), by reducing bioavailability of several amino acids (especially Lys) (Varela, Arce, Marcos, & Castrillón, 1997). The present study also agreed that GC-I preparation led to Lys loss in GC-I hydrolysate (Table 1).…”

Zinc Transport in Caco-2 Cells and Zinc Balance in Rats: Influence of the Heat Treatment of a Casein−Glucose−Fructose Mixture

“…In animals fed a diet containing casein heated with glucose at different temperatures and for different times, reduced weight gain and delayed growth were reported (Chuyen et al, 1994;Lipka and Ganowiak, 1993). This negative effect, although not always seen (Varela et al, 1997), has been attributed to reduced food intake, diarrhea (O'Brien and Walker, 1988), and antinutritional effects (Finot, 1990). Diarrhea in the test animals was not observed, although rats that consumed diet HC-D had softer feces.…”

Long-term feeding effects of dietary protein levels on egg production, immunocompetence and plasma amino acids of laying hens in subtropical condition

“…(1992) concluded that the short‐term protein restriction could increase mortality rate of rats because of Salmonella typhimurium infection, whereas the short‐term calorie restriction improved the survival rate. In addition, nutritionally‐mediated immunological disturbances in animals could occur by long‐term consumption of heat‐processed foods (Varela et al., 1997). To maximise production performance and health, therefore, appropriate period of optimum dietary protein consumption and balancing amino acids have to be studied.…”