Discrete lesions of the area postrema abolish radiation-induced emesis in the dog.

Studies carried out in several mammalian species during the 1950's led to the concept of a 'vomiting center' located in the dorsolateral reticular formation and a 'chemoreceptor trigger zone' (CTZ) within or near the area postrema (AP). This early work suggested that the AP was essential for vomiting induced by a variety of chemical emetics and by ionizing radiation. However, the lesion techniques used often produced significant damage to neural tissue underlying the AP, as well as to the AP itself, making localization of function very difficult. In the present study, electrolytic lesions confined to the AP abolished both radiation- and apomorphine-induced emesis in dogs. Thus, in addition to its postulated function in osmoreception and central cardiovascular regulation, the AP also appears to have a key role in vomiting initiated by chemical emetics and by ionizing irradiation.