ONTOGENY OF EPINEPHRINE, NOREPINEPHRINE, DOPAMINE-BETA-HYDROXYLASE, AND CHROMOGRANIN-A IN THE ADRENAL-GLAND OF PIGS

Objective - To obtain data on the ontogeny of catecholamines and other chromaffin vesicle components, which could serve as a basis for the s tudy of their role during fetal life in normal and pathologic conditio ns. Design - Epinephrine, norepinephrine, dopamine-alpha-hydroxylase, and chromogranin A contents were measured in the porcine adrenal gland during various stages of gestation. Animals-934 porcine fetuses repre senting 23 gestational ages between 43 and 108 days. Procedure-Total h omogenates of adrenal glands were extracted and contents of different neurochemical markers were measured, using high-performance liquid chr omatography, immunoassays, and western blotting. Immunohistochemical s tudies also were performed. Results-Epinephrine and norepinephrine con tents as a function of gestational age can be represented by a sigmoid al curve. Norepinephrine content rises early in gestation, whereas epi nephrine content increases later. Maximal increase was significantly h igher for epinephrine content, A progressive appearance of separate ep inephrine- and norepinephrine-storing cells was documented. Dopamine-P -hydroxylase content as a function of gestational age can be adequatel y represented by a parabolic curve. No quantitative changes in chromog ranin A concentration were observed, but western blotting revealed qua litative changes with progressing gestational age. Conclusions-Importa nt changes occur in catecholamine formation around day 60 of gestation . The sharp increase in epinephrine/norepinephrine contents and the ap pearance of separate epinephrine- and norepinephrine-storing cells may be related to the progressive splanchnic innervation of the adrenal g land. The presence of chromogranin A early in gestation may indicate i ts necessity for catecholamine storage.