Journal of Neuroscience, Vol 10, 2886-2896, Copyright © 1990 by Society for Neuroscience
Asynchronous appearance and topographic segregation of neuropeptide- containing cells in the developing rat adrenal medulla
PD Henion and SC Landis
Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106.
The developmental expression of neuropeptide Y (NPY) and leucine-
enkephalin (L-Enk) was examined in embryonic, early postnatal, and adult
chromaffin cells with double- and triple-label immunocytochemical
techniques and compared to the expression of immunoreactivity for tyrosine
hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT). In
addition, the establishment of preganglionic innervation was assessed by
labeling for choline acetyltransferase (ChAT) and L-Enk. NPY-IR was
detectable on embryonic (E) day 15 in a clustered subpopulation of TH-IR
cells. L-Enk and PNMT-IR cells were initially present on E16 in a separate
nonclustered population of TH-IR cells. By late embryonic development,
twice as many TH-IR cells expressed NPY and 4 times as many expressed L-Enk
as in the adult. In contrast to early embryonic development, NPY-IR was
evident in both the clustered and nonclustered subpopulation of TH-IR cells
at this time. The proportion of NPY-IR chromaffin cells decreased to adult
values during the first postnatal week at the time when obviously clustered
TH-IR cells were no longer observed. The embryonic rise in the proportion
of L-Enk-IR cells correlates with the developmental increase in
glucocorticoid production, while the postnatal decrease corresponds to the
appearance of ChAT-IR in the preganglionic innervation of the adrenal
medulla. These results indicate that NPY and L-Enk are expressed at
different times and in different subpopulations of cells in the embryonic
adrenal. Further, the observation that peptide expression by chromaffin
cells undergoes marked changes during development raises the possibility
that a number of factors including developmental history, environmental
signals and impulse activity play a role in the regulation of neuropeptide
expression in sympathoadrenal derivatives of the neural crest.
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