Influence of vitamin B6 status on aspects of lead poisoning in rats

The effects of vitamin B6 status and lead (Pb) toxicity on aspects of glutathione (GSH) metabolism in rats were examined in a 2 x 2 factorial experiment. The administration of 2000 ppm Pb as Pb acetate.3H2O significantly (P less than 0.05) increased hepatic GSH levels in rats receiving B6-adequate (+B6) but decreased GSH in rats fed B6-deficient (-B6) diets. The addition of Pb to the +B6 diet also increased hepatic glutathione reductase (GSSG-R) activity. Plasma pyridoxal phosphate (PLP), cystathionine and valine levels were decreased by the -B6 diets independent of the presence of Pb. Plasma arginine, alanine, serine and proline levels were increased by Pb in both -B6 and +B6 groups. Glycine levels were increased in -B6 rats only in the absence of Pb while taurine was decreased by Pb only in +B6 rats. There were significant -B6 x Pb interactions for hepatic GSH, cysteine and GSSG-R as well as plasma valine, glycine and proline. These results suggest an influence of B6 status on Pb-induced changes in hepatic GSH, possibly through its role as a co-factor for enzymes involved in amino acid metabolism.