Existence of [(3)H]serotonin binding sites in the rat spinal cord: A developmental study

[(3)H]5-HT specific binding sites have been characterized in the rat spinal cord. Experimental conditions allowed us to study a single class of sites possibly related to the postsynaptic receptor for 5-HT. Binding constants (KD and Bmax) are described for adult and developing animals. No substantial changes in affinity were observed but the number of receptors increased from birth up to day 20 postnatally, stabilizing thereafter. The developmental pattern of a presynaptic marker, tryptophan-5-hydroxylase, was similar to that of binding sites.