PROTEIN FEEDING AND THE ACTIVITY OF ADENOSINE-DEAMINASE AND PURINE NUCLEOSIDE PHOSPHORYLASE IN RAT THYMUS

It is known that the thymus is severely affected by nutritional defici ency. Adenosine deaminase (ADA) and Purine Nucleoside Phosphorilase (P NP) are thought to be important for normal lymphocyte development. The present paper studies the effect provoked on the activity of these th ymic enzymes in growing rats by marginal (PF15), moderate (PF20) and s evere (PF25) protein deprivation and the subsequent oral administratio n of a 20% dietary protein during 9 days (R). Results were expressed a s mu mol uric acid x 10(-1)/W, per five minutes, where W = Tw (mg)/Bw( g)(0.75). (Mean +/- S.D.). Statistical differences between PF15 and Co ntrol (C) in: ADA(17.5+/-4.1 vs. 10.5+/-2.8), PNP (7.1+/-0.8 vs. 3.7+/ -0.9); PF20 and C in:, ADA (15.7+/-4.5 vs. 9.1+/-3.0), PNP (10.3+/-4.1 vs. 3.9+/-1.0); PF25 and C in: ADA (17.0+/-2.6 vs. 9.1+/-3.0) and PNP (11.5+/-4.2 vs. 3.9+/-1.0) were observed (p< 0.01). When PF25 was ref ed with a 20% casein diet(R), activity of ADA and PNP decreased signif icantly when compared to PF25. No statistical differences in ADA and P NP were observed between R and its Control (7.4+/-2.5 vs. 9.3+/-1.8; 3 .6+/-0.5 vs. 3.9+/-0.6, respectively). The results show that protein d eprivation at weaning provokes increase in ADA and PNP activities. The refeeding with a 20% protein diet during 9 days is enough to reverse the effect produced by severe protein malnutrition on ADA and PNP acti vities. (C) 1998 Elsevier Science Inc.