Developmental changes of calpain and calpastatin in rabbit brain

A major part of the Ca-activated proteolytic activity in the soluble fraction from rabbit brain could be due to the activity of the neutral thiol-proteases calpain I and II. The activity of calpains exceeded that of the endogenous inhibitor, calpastatin, at all developmental stages studied. The level of calpains increased rapidly from the prenatal stage to reach a peak 10-20 days postnatally. From this period the level of calpains decreased slowly to reach the adult levels. The level of calpastatin increased steadily from the prenatal stage to old age.