Electrophysiological analysis of chemosensitive neurons within the area postrema of the rat

This chapter presents electrophysiological analysis of chemosensitive neurons within the area postrema of the rat. The chapter demonstrates chemosensitive neurons within the area postrema (AP) electrophysiologically. Two different techniques were employed for chemical stimulation of the AP neurons: (1) the floor of the exposed fourth ventricle was superfused with isotonic glucose solution, hypertonic or hypotonic Ringer solution, or LiCl Ringer solution, (2) these solutions were injected into the left carotid artery. To confirm vagal afferent influences on given AP neurons, single shock electrical stimulation was delivered to the cervical vagal trunks of both sides. Three types of chemosensitive neurons were identified: (1) glucose responsive neurons that may participate in the control of satiety, (2) sodium (osmotic pressure) responsive neurons that may contribute to salt preference or control of water balance, and (3) LiCl responsive neurons that may play a role in conditioned taste aversion. The glucose responsive neurons within the AP may play a role in the control of food intake.