Food deprivation does not potentiate glucose taste reactivity responses ofchronic decerebrate rats

The chronic supracollicular decerebrate (CD) rat fails to increase meal siz e in response to systemic/metabolic aspects of food deprivation. Here we as ked whether or not deprivation increases immediate oral motor responding to taste stimuli (taste reactivity) in CD rats, as it does in neurologically intact controls. The responses of CD rats were evaluated as functions of gl ucose concentration and deprivation state, with taste reactivity responses recorded myographically during 15-s intraoral infusions and during 45-s pos t-infusion periods. Five glucose concentrations (0, 3.2, 6.25, 12.5, 25%) w ere each presented three times during each test session. The rats were test ed when not-deprived (i.e. receiving their full complement of gavage feedin gs), deprived (23.5 h) of food and water, and deprived of food but not wate r. The number of oral motor responses emitted increased monotonically with stimulus concentration: during oral infusions the increase was greatest ove r the lower half of the concentration range, whereas responding increased l inearly with concentration in the post-infusion period. This CD response pr ofile resembled that obtained previously with neurologically intact rats te sted according to the same protocols. In contrast to results obtained in in tact rats, deprivation did not influence the CD's response to glucose at an y concentration or for any observation period. Although the caudal brainste m may receive and process information associated with deprivation state, ne ural interactions between forebrain and brainstem structures appear necessa ry for the behavioral expression of deprivation effects on meal size or, as we can now conclude, on immediate oral motor responses to taste stimuli. ( C) 2000 Elsevier science B.V. All rights reserved.