HEPATIC HISTIDASE GENE-EXPRESSION RESPONDS TO PROTEIN REHABILITATION IN UNDERNOURISHED GROWING RATS

We studied the effect of nutritional rehabilitation with a 6, 18 or 50 % casein diet in undernourished rats on histidase (Hal) expression. Un dernutrition was induced by feeding rats a 0.5% casein diet for 5 wk, Over this period, growth, serum total proteins and insulin-like growth factor-I (IGF-I) levels were significantly lower than those of rats t hat freely consumed an 18% casein diet. During this period, undernutri tion also significantly reduced Hal activity and Hal-mRNA concentratio n. Nutritional rehabilitation for 21 d with a 6% casein diet did not c hange any of these variables, Nutritional rehabilitation with an 18 or 50% casein diet for 1 d initiated the restoration of Hal activity and mRNA concentration. After 10 d of consuming 18 or 50% casein diets, H at activity was 5- and 14-fold, and mRNA concentration was 8,5- and 23 -fold higher, respectively, than in the protein-undernourished group ( PU). During this period, body weight, total serum proteins and IGF-I l evels were also significantly (P < 0.05) higher than those of the PU g roup, At the end of 21 d of rehabilitation with an 18 or 50% casein di et, Hal activity was 14- and 31-fold higher and Hat mRNA concentration was 10- and 24-fold higher, respectively, than in the PU group. In co nclusion, our data showed that rehabilitation of undernourished rats w ith a 6% casein diet was not sufficient to re-establish growth indicat ors, Hal activity or gene expression, and that nutritional rehabilitat ion with an 18 or 50% casein diet effectively re-established body weig ht, biochemical variables and the capacity of histidase gene expressio n to eliminate the excess of protein.