Abstract
Transsynaptic activity difEerentially regulates biosynthesis of sympathoadrenal catecholamines (CA) and co-localized opiate peptides in the rat (La Gamma, et al PNAS 82: 8252, 1985). We determined whether similar mechanisms were operative during development. Adrenal leu-enkephalin (LEU), first detected at E0.75, increased 20 fold during maturation from birth to adulthood while medullary weight increased only 10 fold. Since medullary cells do not divide after birth, this represents a specific maturational increase In LEU content per chromaffin cell. In adult medullae, decreasing transsynaptic activity through adrenal denervation or explantation results in a 30 to 50 fold increase in LEU (La Gamma, et al Science 224:1102, 1984). In contrast, LEU levels in denervated or explanted medullae from neonatal rats (<10 days) do not. Prolonged denervation (5 to 21 days) blocked even the normal maturational increase in LEU. Moreover, increased activity through nicotine treatment also failed to affect LEU levels in neonates. Specific deficits in nicotinic receptor transduction mechanisms or immaturity of opiate biosynthesis pathways may account for these observations. Therefore, like CA pathways, adrenal opiate peptides require presynaptic regulatory signals to achieve normal development. Defining transmitter ontogeny and identifying essential cellular processes will help elucidate mechanisms of sympathoadrenal exhaustion or dysfunction and thus promote the development of innovative therapy for syndromes of autonomic dysfunction in neonates. Supported in part by the March of Dimes Foundation.
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La Gamma, E., Adler, J. DEVELOPMENT OF TRANSSYNAPTIC REGULATION OF ADRENAL TRANSMITTERS. Pediatr Res 21 (Suppl 4), 217 (1987). https://doi.org/10.1203/00006450-198704010-00303
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DOI: https://doi.org/10.1203/00006450-198704010-00303