EFFECTS OF FETAL GROWTH-RETARDATION ON THE DEVELOPMENT OF CENTRAL ANDPERIPHERAL CATECHOLAMINERGIC PATHWAYS IN THE SHEEP

Regional norepinephrine and dopamine content and cerebral alpha1- and beta-adrenergic receptor mechanisms were studied in the brain of sham operated control and single umbilical artery ligation (SUAL) induced g rowth retarded newborn sheep. Brain sparing was evidenced by relative preservation of brain weight compared to other organ systems. Norepine phrine and dopamine content of the brain were not affected by SUAL. Th is is in contrast to decreased norepinephrine levels in the brown fat, a normally densely innervated peripheral tissue. Alpha1- and beta-adr energic receptor numbers and affinity states were similar between the two groups. Coupling between beta-receptor and guanine nucleotide stim ulatory protein and agonist stimulated adenylyl cyclase activity were unaffected by SUAL. Brain regional DNA content and protein/DNA ratios were not different between the two groups. These data suggest that sin gle umbilical artery ligation induced fetal growth retardation modifie s peripheral but not central catecholaminergic pathways in the sheep. Both growth and expression of specific catecholaminergic signal transd uction system are protected in the brain.