 |
||||
|
||||
|
||||
|
||||
Previous Article | Next Article
The Journal of Neuroscience, June 1, 2001, 21(11):4032-4041
Neurons of a Limited Subthalamic Area Mediate Elevations in Cortical Cerebral Blood Flow Evoked by Hypoxia and Excitation of Neurons of the Rostral Ventrolateral Medulla
Eugene V. Golanov, John R. C. Christensen, and Donald J. Reis 
Division of Neurobiology, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, New York, New York 10021
Sympathoexcitatory reticulospinal neurons of the rostral ventrolateral medulla (RVLM) are oxygen detectors excited by hypoxia to globally elevate regional cerebral blood flow (rCBF). The projection, which accounts for >50% of hypoxic cerebral vasodilation, relays through the medullary vasodilator area (MCVA). However, there are no direct cortical projections from the RVLM/MCVA, suggesting a relay that diffusely innervates cortex and possibly originates in thalamic nuclei. Systematic mapping by electrical microstimulation of the thalamus and subthalamus revealed that elevations in rCBF were elicited only from a limited area, which encompassed medial pole of zona incerta, Forel's field, and prerubral zone. Stimulation (10 sec train) at an active site increased rCBF by 25 ± 6%. Excitation of local neurons with kainic acid mimicked effects of electrical stimulation by increasing rCBF. Stimulation of the subthalamic cerebrovasodilator area (SVA) with single pulses (0.5 msec; 80 µA) triggered cortical EEG burst-CBF wave complexes with latency 24 ± 5 msec, which were similar in shape to complexes evoked from the MCVA. Selective bilateral lesioning of the SVA neurons (ibotenic acid, 2 µg, 200 nl) blocked the vasodilation elicited from the MCVA and attenuated hypoxic cerebrovasodilation by 52 ± 12% (p < 0.05), whereas hypercarbic vasodilation remained preserved. Lesioning of the vasodilator site in the basal forebrain failed to modify SVA-evoked rCBF increase. We conclude that (1) excitation of intrinsic neurons of functionally restricted region of subthalamus elevates rCBF, (2) these neurons relay signals from the MCVA, which elevate rCBF in response to hypoxia, and (3) the SVA is a functionally important site conveying vasodilator signal from the medulla to the telencephalon.
Key words: cerebral blood flow; neural regulation; electroencephalogram; hypoxia; thalamus; medulla
Correspondence should be addressed to Dr. Eugene Golanov, Division of Neurobiology, Department of Neurology and Neuroscience, Weill Medical College of Cornell University, 411 East 69th Street, New York, NY 10021. E-mail: egolano{at}mail.med.cornell.edu.
Copyright © 2001 Society for Neuroscience 0270-6474/01/21114032-10$05.00/0
This article has been cited by other articles:
K. Xu and J. C. LaManna
Chronic hypoxia and the cerebral circulation
J Appl Physiol, February 1, 2006; 100(2): 725 - 730.
[Abstract] [Full Text] [PDF]
J. C. LaManna, J. C. Chavez, and P. Pichiule
Structural and functional adaptation to hypoxia in the rat brain
J. Exp. Biol., August 15, 2004; 207(18): 3163 - 3169.
[Abstract] [Full Text] [PDF]
|
|
|
|
 |
|