2',3'-Cyclic Nucleotide 3'-Phosphodiesterase and 5'-Nucleotidase in the Central Nervous System of a Myelin-Deficient Rat Mutant

2',3'-Cyclic nucleotide 3'-phosphodiesterase activity was examined in brains and spinal cords of normal and myelin-deficient Wistar rats. While the activity in normal brains increased from 0.2 mumol/min/mg protein (units) at 6-10 days to 3.5 units at 25 days of postnatal age, the activity in the myelin-deficient rat remained at 0.2-0.3 units over the same period. In spinal cord, the normal activities were 5.7 and 10.9 units at 12 and 20 days, respectively, whereas they declined in the myelin-deficient rat from 1.06 to 0.79 units for the same age points. 5'-Nucleotidase activities in brain and spinal cord were normal in the myelin deficient rat at both ages.