Sympathoexcitation and pressor responses induced by ethanol in the central nucleus of amygdala involves activation of NMDA receptors in rats

Andrew D. Chapp , Le Gui , Michael J. Huber , Jinling Liu , Robert A. Larson , Jianhua Zhu , Jason R. Carter , Qing-Hui Chen. American Journal of Physiology - Heart and Circulatory Physiology Published 1 September 2014Vol. 307 no. 5, H701-H709DOI: 10.1152/ajpheart.00005.2014. Ingestion of alcohol leads to pressor and sympathoexicition. This purpose of this study was to elucidate the mechanism responsible for the activation of the sympathetic nervous system. By using microinjection technique they demonstrated that ethanol and acetate, a byproduct of ethanol caused pressor and increases in SSNA and LSNA when injected into the amygdala (CeA).  In order to determine whether this response is being mediated by glutamate, they injected kyn, an EAA receptor blocker, NMDAR blocker and a non NMDAR blocker mixed with ethanol. They found that Kyn and the NMDAR blocker both attenuated the pressor response and SSNA. Then in order to determine whether the RVLM was playing role in the response kyn was injected into the RVLM they found that this also attenuated the response. Finally they showed that anatomically there was an connection between RVLM and CeA and that NMDAR were present on CeA-RVLM neurons. These data show that alcohol and alcohol metabolites can lead to activation of RVLM neurons which may be the cause of increase sympathetic outflow in response to alcohol consumption.-MD