Journal of Neuroscience, Vol 10, 161-168, Copyright © 1990 by Society for Neuroscience
Postembryonic alteration of transmitter phenotype in individually identified peptidergic neurons
NJ Tublitz and AW Sylwester
Institute of Neuroscience, University of Oregon, Eugene 97403.
Many neurons are now known to undergo dramatic morphological or biochemical
changes long after they have completed differentiation and maturation. The
ability of fully mature neurons to alter their transmitter phenotype has
been amply demonstrated in culture, but direct in vivo data on single
neurons have been difficult to obtain. Here we show that a set of 4
individually identified neurosecretory neurons in the moth Manduca sexta,
previously demonstrated to contain the peptide hormone bursicon, also stain
with a monoclonal antibody directed against 2 insect cardioacceleratory
peptides (CAPs). These lateral cells exhibit CAP-like immunoreactivity in
larvae but not in pupae or adults, in contrast to other CAP-containing
neurons which are strongly immunoreactive in all postembryonic stages.
Biochemical analyses using high-pressure liquid chromatography confirm that
the lateral neurons in larvae contain CAP2, one of the CAPs. CAP
measurements of cell clusters containing these cells indicate high levels
only in caterpillars. When the same neurosecretory cells are individually
dissected and assayed for CAP bioactivity, high CAP levels are again found
in larvae, whereas the same neurons in pupae show no such CAP bioactivity.
Simultaneous determinations of both bursicon and CAP levels in single
lateral cells indicate that these cells express high levels of CAP activity
and low amounts of bursicon in larvae yet are solely bursicon-containing in
pupae and adults. Thus, by demonstrating that these cells alter their
secretory profile in vivo during metamorphosis, our results confirm the
notion that functionally mature neurons are capable of altering their
transmitter expression after the completion of embryonic development.