Abstract
Postsynaptic serotonin-sensitive adenylate cyclase with an apparent affinity of 1 µM for serotonin (5-HT) was detected in various structures of the central nervous system in the rat and the guinea pig. At birth, the regional distribution of this enzyme in the rat brain was closely correlated with the topographical distribution of the serotoninergic innervation in young (9-day-old) as well as adult animals. Electrolytic raphe lesions made on the fourth day after birth, which produced 90% degeneration of serotoninergic innervation in rat colliculi, did not alter the characteristics (apparent affinity and maximal activity) of the serotonin-sensitive adenylate cyclase in this area. This suggests that the serotonin-sensitive adenylate cyclase is associated with postsynaptic serotoninergic receptors in the brain. During development, in both the rat and the guinea pig, the amount of cyclic 3',5'-AMP formed in response to an optimal concentration of serotonin in a given area remained constant. This is in contrast to the amount of cyclic AMP formed in response to an optimal concentration of dopamine, which increased 6-fold in the rat striatum between the second and 23rd days after birth. The lack of correlation between the regional distribution of the dopamine-sensitive adenylate cyclase and serotoninergic innervation and between the serotonin-sensitive adenylate cyclase and dopaminergic innervation further emphasizes that the serotonin- and dopamine-sensitive adenylate cyclases are each associated with specific receptors in the rat brain.
ACKNOWLEDGMENT We thank Dr. J. Glowinski for many stimulating discussions during the preparation of the manuscript.
- Copyright © 1978 by Academic Press, Inc.
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