Central connections of the hepatic branch of the vagus nerve: a horseradish peroxidase histochemical study.

The hepatic branch of the vagus nerve has been implicated as an important source of afferent input controlling both physiological and behavioral homeostasis. In addition, it is clear that parasympathetic efferents to the liver can significantly alter hepatic functions. In order to begin physiological studies on the nature of hepatic afferent and efferent relations, it will be necessary to understand the central anatomical organization of the components of this small visceral nerve. By carefully exposing and dissecting the hepatic branch of the vagus and applying crystalline horseradish peroxidase (HRP) to it, we were able to elucidate a predominant pattern of afferent terminations within the left subnucleus gelatinosus, the medial division of the left solitary nucleus and the left lateral edge of the area postrema. Efferent nuclei were concentrated in the left dorsal motor nucleus of the vagus (DMN) with a few scattered neurons located in the right DMN as well as the left anterior nucleus ambiguous.