Effects of chronic ascorbic acid deficiency on guinea pig lysosomal hydrolase activities

Previously we have observed increased specific activities of several lysosomal hydrolases in scorbutic guinea pigs and thus the specificity of this effect was examined in guinea pigs marginally deficient in ascorbic acid (AA). Guinea pigs were fed an AA-deficient diet for 2 weeks to deplete body AA pools and then fed a stock diet containing 0.5 mg AA/g diet or the deficient diet plus oral administration of 10 mg AA/day, 1 mg AA/100 g body weight or 0.5 mg AA/100 g body weight each day. Animal were periodically killed during the 12-week experiment and lysosomes isolated from individual livers and analyzed. Serum and brain AA declined when AA was withheld, returned to normal when the stock diet or 10 mg AA were fed but remained at low levels on administation of 1.0 mg or 0.5 mg AA/100 g body weight. Brain norepinephrine followed a similar pattern to brain AA and was opposite to the pattern observed for dopamine. In guinea pigs receiving 1 mg AA/100 g body weight, amine concentrations slowly returned to normal after 8 weeks. Serum hexosaminidase and lysosomal cathepsins A and B were unchanged during the experiment, whereas lysosomal hexosaminidase and acid phosphatase were significantly higher when the experiment was terminated.