Md. Cassell et al., Glycine receptor (gephyrin) immunoreactivity is present on cholinergic neurons in the dorsal vagal complex, NEUROSCIENC, 95(2), 2000, pp. 489-497
We previously demonstrated that microinjection of exogenous glycine into th
e nucleus tractus solitarii of anesthetized rats elicits responses that are
qualitatively like those elicited by microinjection of acetylcholine at th
e same site. The responses to glycine, like those to acetylcholine, are blo
cked by administration of a muscarinic receptor antagonist and prolonged by
administration of an acetylcholinesterase inhibitor. Furthermore, glycine
leads to release of acetylcholine from the nucleus tractus solitarii and su
rrounding dorsal vagal complex. An anatomical framework for interactions be
tween glycinergic and cholinergic neurons was established by studies that i
dentified glycine terminals and receptors in the dorsal vagal complex. The
current study investigated the relationship between glycine receptors and n
euronal elements that were immunoreactive for choline acetyltransferase in
the dorsal vagal complex. Neurons that were immunoreactive for choline acet
yltransferase were located in the dorsal motor nucleus of the vagus, hypogl
ossal nucleus and nucleus ambiguus, and stained cells were also present in
medial, intermediate, and ventrolateral subnuclei of the nucleus tractus so
litarii. We found that glycine receptors, immunolabeled with an antibody to
gephyrin, were present on cholinergic dendrites in the nucleus tractus sol
itarii. Gephyrin immunoreactivity was also present on dendrites that did no
t stain for choline acetyltransferase.
These data further support the contribution of cholinergic neurons in media
ting cardiovascular responses to glycine in the nucleus tractus solitarii.
(C) 1999 IBRO. Published by Elsevier Science Ltd.