Increased Dietary Salt Enhances Sympathoexcitatory and Sympathoinhibitory Responses From the Rostral Ventrolateral Medulla

Julye M. Adams, Christopher J. Madden, Alan F. Sved, Sean D. Stocker (Hypertention. 2007;50:354-359.) In this article they investigated glutamate and gaba responses in RVLM during high salt diet. There was a control group that was given just water and another given 1% NaCl (high salt diet group). In the high salt diet group there were enhanced responses to Glutamate for MAP, renal and splanchnic nerve activity. In response to GABA there were enhanced depressor responses along with enhanced decreases in renal and splanchnic sympathetic nerve activity in the high salt diet group when compared to the control. They did a time course in order to see how long it would take to develop enhanced glutamate and gaba responses. They gave 1%$ NaCl for 1, 7, 14 and 21 days. They that at 14 days there was greater increases to glutamate and gaba for ABP and renal. Next they wanted to see if the changes were reversible. They gave water instead of 1% NaCl to rats for 1 or 7 days. They found that the 7 day water treatment lead to reversal of the effects of drinking 1% NaCl for 14days, the responses to glutamate and gaba were no different than control animals. These data suggest that high salt diet leads to both enhanced glutamate and gaba sensitivity in RVLM and that these neuroplastic changes are reversible with treatment. -MD