[The cephalic phase of insulin secretion in man]

Abstract

In human subjects, a reflex secretion of insulin has been observed following the stimulation of cephalic sensory receptors by food. In animals, such a response is recognised and appears to contribute to energy regulation. In man, its amplitude is very variable and "negative responses" have been reported. Negative responses can be interpreted as, the descending phase of the spontaneous oscillations of insulinaemia which have been described in animals and humans. This observation shows that spontaneous oscillations should be taken into consideration when evaluating or describing the responses to meal stimulation. It thus becomes possible to attribute a significant part of the variability to the subjects' individual sensitivity and to the hedonic value of meals. The response can be conditioned to arbitrary stimuli and then be evoked without exposure to food. Its role in energy regulation has not been demonstrated in man, although certain studies suggest that it may augment the metabolic rate. Large responses are associated with large, palatable meals, but it is not known whether the insulin response is merely a reflection of the sensory characteristics of food or whether it contributes to the stimulation to eat.