Aphagia and adipsia after kainic acid lesioning of the dorsomedial hypothalamic area

Abstract

Unlike rats which have electrolytic dorsomedial hypothalamic area lesions and are hypophagic and hypodipsic, the rats of the present study with dorsomedial hypothalamic area, kainic acid lesions (KAL) were postoperatively aphagic and adipsic. Subsequently, KAL rats rejected chow or a high-fat diet but ate a 30% sucrose-chow diet. Similarly the KAL rats were adipsic but drank a 30% sucrose solution. Slowly most of the KAL rats began to eat chow and drink tap water but remained hypophagic and hypodipsic. When tested for glucoprivic-induced feeding using 2-deoxy-D-glucose (200 or 400 mg/kg) the KAL rats, in contrast to the sham-operated controls, did not increase their food intake. During water deprivation the recovered KAL rats that would drink tap water ate, and following it they responded with an adequate increase in water consumption. During food deprivation the KAL rats, whether eating chow or sucrose-chow diet, drank, and subsequently the normally hypophagic rats actually ate more than the controls. Although the growth rate (linear and ponderal) of KAL rats was reduced compared with that of the controls, their body composition by indirect measurement was normal. The present data indicate that most of the dorsomedial hypothalamic syndrome results from damage to DMHA neurons and not to fibers of passage.