EXTENSIVE PROJECTIONS FROM THE MIDBRAIN PERIAQUEDUCTAL GRAY TO THE CAUDAL VENTROLATERAL MEDULLA - A RETROGRADE AND ANTEROGRADE TRACING STUDY IN THE RAT

Citation
S. Chen et G. Astonjones, EXTENSIVE PROJECTIONS FROM THE MIDBRAIN PERIAQUEDUCTAL GRAY TO THE CAUDAL VENTROLATERAL MEDULLA - A RETROGRADE AND ANTEROGRADE TRACING STUDY IN THE RAT, Neuroscience, 71(2), 1996, pp. 443-459
Citations number
71
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Neurosciences
Journal title
ISSN journal
0306-4522
Volume
71
Issue
2
Year of publication
1996
Pages
443 - 459
Database
ISI
SICI code
0306-4522(1996)71:2<443:EPFTMP>2.0.ZU;2-Y
Abstract
We investigated the innervation of the caudal ventrolateral medulla by the midbrain periaqueductal gray in the rat using retrograde and ante rograde tract-tracing. Iontophoretic injection of Fluoro-Gold or chole ra toxin B subunit into the caudal ventrolateral medulla resulted in r etrogradely labeled neurons in discrete regions of the periaqueductal gray. These labeled cells were observed throughout the rostrocaudal ex tent of the periaqueductal gray and were distributed (as percentage of total labeled cells) in its lateral (53-67%), ventrolateral. (14-28%) , ventromedial (7-16%) and dorsomedial aspects (7-10%). About 70-72% o f labeled cells were found in the caudal half of the periaqueductal gr ay and 28-30% in the rostral half In the ventromedial periaqueductal g ray, more labeled cells were seen in the contralateral side (5-13%) th an the ipsilateral side (2-3%), whereas for other periaqueductal gray areas labeling was preferentially ipsilateral. Phaseolus vulgaris leuc oagglutinin anterograde tracing was used to confirm the retrograde lab eling results. Following iontophoretic injection into the periaqueduct al gray, labeled fibers and terminals were observed throughout the ros trocaudal extent of the caudal. ventrolateral medulla. Injections in t he lateral and/or ventrolateral aspect of the periaqueductal gray yiel ded more anterograde labeling in the ipsilateral than the contralatera l caudal ventrolateral medulla, while injections in the ventromedial a spect of the periaqueductal gray produced labeling preferentially in t he contralateral caudal ventrolateral medulla. The present study indic ates that specific regions of the periaqueductal gray project to the c audal ventrolateral medulla and may regulate cardiovascular and respir atory functions through these connections.