Area postrema: part of the autonomic circuitry of caloric homeostasis

Investigations in which lesion techniques are used suggest a role for the area postrema (AP) in caloric homeostasis. Ablations of the AP in rat are associated with temporary hypophagia, hypodipsia, and rapid body weight loss. This is followed by a steady period of relatively normal eating and drinking and body weight gain. This steady period is characterized specifically by lowered body weight maintenance levels, overingestion of palatable foods, and attenuated taste aversion learning and glucoprivic feeding. These effects cannot be attributed simply to lesions of central terminations of gustatory and visceral afferents. The AP may be involved in feeding behaviors that are triggered by chemical signals in the blood or cerebrospinal fluid. In addition, the AP along with the adjacent nucleus tractus solitarii (NTS) seems to be part of the central autonomic system subserving caloric homeostasis; this system includes the lateral hypothalamus, which has a well-documented role in energy balance. The contribution of the AP along with the NTS must be considered with respect to their relationship to other structures within this system.