Functional coupling between transient declines in blood glucose and feeding behavior: temporal relationships.

To assess the strength and time course of the functional coupling between transient declines in blood glucose and meal initiation, access to food was prevented throughout declines followed by restoration of access to food when glucose returned to baseline. Neither preventing access to nor the absence of food affected the time course of the decline in blood glucose and the latency to food seeking behavior. When access to food was restored six to eight minutes after the blood glucose returned to baseline, no food seeking behavior or feeding occurred until after a second decline in glucose had occurred about one hour later. However, when access to food was restored before glucose returned toward baseline, feeding began within two minutes. Blood glucose did not decrease following presentation of novel foods and feeding occurred rapidly without a prior decline in blood glucose. Therefore, transient declines in blood glucose strongly signalled food seeking and meal initiation but this functional coupling was of short duration (approximately 12 min) and persisted less than six minutes after the blood glucose had returned to baseline. The transient decline in blood glucose appears to be an endogenous, glucose dependent cue for food seeking and meal initiation.