Twenty-Four-Hour Variations in Ornithine Decarboxylase and Acid Phosphatase in Mice

Polyamines are essential for cell growth and differentiation. Ornithine decarboxylase (ODC) is the rate-limiting enzyme in polyamine biosynthesis. Acid phosphatases (AP) are lysosomal enzymes that are important in normal intracellular metabolism. Twenty-four-hour variations in these enzymes may be important in understanding the temporal responses of different tissues to various stimuli. The purpose of this study was to examine a variety of tissues for fluctuations in the levels of ODC and AP over a 24-hr period. Significant circadian variations in the amount of ODC activity were observed in all tissues examined. Activity of AP varied with time of day in the liver, kidney, and heart. The highest and lowest measurements of ODC activity were as follows: liver, 81.5 ± 7.0, 47.9 ± 4.4; colon, 11.7 ± 1.2, 3.1 ± 0.7; stomach 3.1 ± 0.4, 0.9 ± 0.1; kidney, 420.9 ± 0.9, 67.5 ± 0.8; and heart, 4.7 ± 1.0, 2.5 ± 0.2. The highest and lowest measurements of AP activity were as follows: liver 3.8 ± 0.1, 2.8 ± 0.1; kidney, 3.4 ± 0.1, 1.9 ± 0.1; and heart, 2.6 ± 0.1, 2.0 ± 0.1. These findings suggest that rhythmic fluctuations in polyamine biosynthesis and lysosomal enzymes may influence other metabolic pathways differentially throughout 24 hr.