Lateral parabrachial lesions attenuate ingestive effects of area postrema lesions.

Lesions of the area postrema and adjacent nucleus of the solitary tract (AP lesions) cause rats to consume increased amounts of palatable food in short duration tests. Because the lateral parabrachial nucleus (lPBN) receives a prominent afferent projection from the AP and adjacent nucleus of the solitary tract, it is possible the lPBN plays a role in the altered ingestive behaviors observed in AP-lesioned rats. The present study examines the role of the lPBN in overingestion of highly palatable foods subsequent to AP lesions. We found that lesions of the lPBN alone did not cause rats to consume increased amounts of palatable food. Rather, when lPBN lesions were produced before AP lesions, increased intake of highly palatable food did not occur. Moreover, when AP-lesioned rats received subsequent lPBN lesions, the previously established overingestion of palatable foods was abolished. These results indicate that the lPBN is necessary in the pathogenesis of AP lesion-induced overingestion of highly palatable foods.