Developmental expression and corticosterone inhibition of adenosine deaminase activity in different tissues of mice

The activity expression and corticosterone inhibition of adenosine deaminase (ADA) were studied in the spleen, stomach, and liver of mice at various postnatal ages. The specific activity of ADA is very low in the spleen and stomach of 5- and 10-day-old mice, and increases significantly (2.5- to 3.0-fold) in 20- and 30-day-old animals. Its level shows a further increase in the spleen of 60-day-old mice while stomach increase of ADA is not significant. In contrast, the activity of ADA is significantly higher in the liver of 5- and 10-day-old mice, decreases markedly (2.5-fold) in 20- and 30-day-old animals and shows a sharp increase in the liver of 60-day-old mice. Corticosterone administration brings a marked inhibition in the activity of ADA at all ages studied in the spleen and stomach whereas it inhibits the liver ADA only at 30 and 60 days postnatal age. These findings suggest an age- and tissue-specific expression of ADA activity and also indicate corticosterone as an inhibitory regulator of this enzyme.