Glucose-responsive neurons exist within the area postrema of the rat: in vitro study on the isolated slice...

Responses to glucose of spontaneously active neurons were investigated by extracellular recording in the rat area postrema slice preparations (in vitro). Among 67 spontaneously active neurons, 16 neurons displayed a marked increase or decrease in discharge rate in response to increases or decreases of the glucose concentration in perfusate. These results confirm the existence of glucose-responsive neurons within the area postrema suggested in prior in vivo experiments. Response to CCK or dopamine was also examined on the isolated area postrema slices. The neuron that showed a marked increase in discharge rate responding to glucose elicited a marked increase of discharge rate in response to 2.1 microM CCK, suggesting that glucose and CCK affect the same neurons. Some neurons showed a marked increase or decrease in the discharge rate in response to 20 microM dopamine, but these neurons showed neither response to CCK nor to glucose. It is likely that different neuronal networks in the area postrema contribute to control of ingestion and to initiation of nausea.