Maturation of Indoleamine Metabolism in the Spinal Cord of the Mouse

The maturation of various enzymes and intermediates of the 5-hydroxytryptamine (5-HT) biochemical pathway have been measured in the spinal cord of the mouse between 1 day postpartum and adulthood. During the early postnatal period, most components are adult-like or near adult-like, increase to levels greater than the adult by the second week, and return to adult levels thereafter. 5-HT, however, never exceeds adult level and does not attain it until week 4. The early maturation of 5-HT metabolism in the cord is in keeping with the caudal/rostral gradient of maturation in the brain. Possible reasons for this are discussed.