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GABAergic neurons innervating the preganglionic cardiac vagal neurons in the dorsal motor nucleus receive tonic glutamatergic control

Wang Jijiang, Chen Yonghua, Li Keyong, Sun Fengyan

National Key Laboratory of Medical Neurobiology, Shanghai Medical College, Fudan University.Shanghai 200032

Abstract

The glutamatergic innervations and the GABAergic innervations are respectively the major excitatory and inhibitory inputs of preganglionic cardiac vagal neurons (CVNs). Whether and how these two kinds of innervations interact in the regulation of CVNs is unknown. Using retrograde fluorescent labeling of CVNs and voltage patch-clamp technique, we demonstrated that mixed global application of glutamatergic NMDA and non-NMDA antagonists AP_(5) and CNQX, while had no effect on the GABAergic synaptic events of the CVNs in the nucleus ambiguus (NA), significantly decreased the GABAergic synaptic events of the CVNs in the dorsal motor nucleus of the vagus (DMNX). These results suggest that the GABAergic neurons preceding the CVNs in the DMNX receive tonic glutamatergic control, whereas the GABAergic neurons preceding the CVNs in the NA receive little, if any, glutamatergic innervations. This differential central regulation of the CVNs in the DMNX from those in the NA might be a possible mechanism that enables the CVNs in the DMNX play different roles from those in the NA in the parasympathetic control of heart rate and cardiac functions.

Key words: Nucleus ambiguus;Cardiac;Vagus nerve;Preganglionic;Synaptic

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Citing This Article：

Wang Jijiang, Chen Yonghua, Li Keyong, Sun Fengyan. GABAergic neurons innervating the preganglionic cardiac vagal neurons in the dorsal motor nucleus receive tonic glutamatergic control. Acta Physiol Sin 2005; 57 (6): (in Chinese with English abstract).