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Published Online
on June 8, 2009

Hypertension. 2009
Published online before print June 8, 2009, doi: 10.1161/HYPERTENSIONAHA.108.127803
A more recent version of this article appeared on August 1, 2009
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Submitted on December 10, 2008
Revised on January 7, 2009

Ventral Lamina Terminalis Mediates Enhanced Cardiovascular Responses of Rostral Ventrolateral Medulla Neurons During Increased Dietary Salt

Julye M. Adams; Megan E. Bardgett; and Sean D. Stocker*

From the Department of Physiology, University of Kentucky, Lexington.

* To whom correspondence should be addressed. E-mail: sean.stocker{at}uky.edu.

Abstract—Increased dietary salt enhances sympathoexcitatory and sympathoinhibitory responses evoked from the rostral ventrolateral medulla (RVLM). The purpose of the present study was to determine whether neurons of the forebrain lamina terminalis (LT) mediated these changes in the RVLM. Male Sprague-Dawley rats with and without LT lesions were fed normal chow and given access to water or 0.9% NaCl for 14 to 15 days. Unilateral injection of L-glutamate into the RVLM produced significantly larger increases in renal sympathetic nerve activity and arterial blood pressure of sham rats ingesting 0.9% NaCl versus water. However, these differences were not observed between ventral LT-lesioned rats drinking 0.9% NaCl versus water. Similar findings were observed when angiotensin II or {gamma}-aminobutyric acid was injected into the RVLM. Interestingly, a subset of animals drinking 0.9% but with damage restricted to the organum vasculosum of the lamina terminalis did not show enhanced responses to L-glutamate or {gamma}-aminobutyric acid. In marked contrast, RVLM injection of L-glutamate or {gamma}-aminobutyric acid produced exaggerated sympathetic nerve activity and arterial blood pressure responses in animals drinking 0.9% NaCl versus water after an acute ventral LT lesion or chronic lesion of the subfornical organ. Additional experiments demonstrated that plasma sodium concentration and osmolality were increased at night in rats ingesting 0.9% NaCl. These findings suggest that neurons of the ventral LT mediate the ability of increased dietary salt to enhance the responsiveness of RVLM sympathetic neurons.


Key words: brain • sodium • hypertension • blood pressure • sympathetic nerve activity