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Fine structure and plasticity of barosensitive neurons in the nucleus of solitary tract
Author(s) -
Chan Raymond K.W.,
Peto Charles A.,
Sawchenko Paul E.
Publication year - 2000
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/1096-9861(20000703)422:3<338::aid-cne2>3.0.co;2-2
Subject(s) - solitary tract , biology , golgi apparatus , nucleus , baroreceptor , anatomy , neuroscience , area postrema , endoplasmic reticulum , microbiology and biotechnology , endocrinology , heart rate , blood pressure
Intravenous phenylephrine (PE) activates neurons in the nucleus of the solitary tract (NTS) whose distribution conforms to those of central projections of the carotid sinus and aortic depressor nerves. This was exploited to permit fine structural characterization of cells presumed to compose the first station in the processing of arterial baroreceptor input, and their responses to stimulation. Rats were perfused at varying intervals after PE injection, and sections through the baroreceptor afferent zone of the NTS prepared for preembedding immunolocalization of Fos‐immunoreactivity. Labeled neurons composed a continuous strip extending from the dorsal part of the commissural NTS (NTScom) to the dorsal subnucleus at the level of the area postrema (NTSap). PE‐sensitive neurons in these regions were medium‐sized, round to ovoid in shape, with scant cytoplasm and an unremarkable complement of organelles. Distinctive features included extensively invaginated nuclei and well‐developed Golgi apparati; Fos‐ir cells in the NTSap were distinguished from those in NTScom by virtue of better‐developed rough endoplasmic reticulum and Golgi, and less convoluted nuclei. Proximal synaptic input to PE‐sensitive neurons was sparse and was provided by terminals containing predominantly small, clear synaptic vesicles that formed mainly symmetric junctions with somata and primary dendrites. Prolonged stimulation was accompanied by accentuation of nuclear invaginations, marked accumulation of heterochromatin at their apices, and evidence of enhanced Golgi activity (vesicular budding). These may represent adaptations to facilitate changes in gene expression, to maintain neurotransmitter availability, or both, in the face of a persistent hypertensive challenge. J. Comp. Neurol. 422:338–351, 2000. © 2000 Wiley‐Liss, Inc.