Elevations of plasma glucose do not support taste-to-postingestive consequence learning

Abstract

We examined whether elevations in plasma glucose are a sufficient postingestive consequence to support taste-to-postingestive consequence learning. Because real, but not sham, feeding supports taste-to-postingestive consequence learning, we recorded changes in plasma glucose during sham and real feeding. For the 1st 15 min of the meal, both sham and real feeding produced similar elevations in plasma glucose. Thereafter, real feeding produced sustained elevations in plasma glucose, whereas sham feeding did not. However, mimicking the plasma glucose profile of real feeding in the sham feeding rat by infusing glucose intravenously did not produce taste-to-postingestive consequence learning. Using radiolabeled sucrose, we determined that the rise in plasma glucose during sham feeding results from absorption of nutrient. We conclude that elevations in plasma glucose in isolation are not a sufficient consequence to support taste-to-postingestive consequence learning.