Effects of D-glucose anomers on sweetness, taste and gastric acid secretion in man

Beverage viscosity is inversely related to postprandial hunger in humans

Accumulating evidence indicates that energy-yielding beverages evoke weaker appetitive responses than more solid food items, but the properties responsible have not been characterized. The present study attempted to isolate an influence of viscosity. At weekly intervals, 84 adults ingested 325-ml (220 kcal) shakes that were matched on weight, volume, temperature, energy, macronutrient content, energy density, rate of consumption, cognitive expectations, palatability, appearance, and requirements for mechanical processing, but varied in viscosity. Twice appetitive ratings were obtained over the subsequent 4 h, while all intake was proscribed, and twice ratings were kept until the first spontaneous eating occasion comprised of > or =100 kcal. Dietary intake was recorded over the 24 h after shake ingestion. Significantly greater and more prolonged reductions of hunger were observed with the thicker shake. No significant differences were noted in the size or time to first meal or 24 h energy intake. These data indicate viscosity exerts an independent inverse effect on hunger in humans.

Control of motor and secretory functions of the stomach by a portal glucose signal

D-glucose solution injected into the portal vein influences efferent tonic activities of the vagal nerve innervating the stomach. This suggested the existence of a neural connection between hepatic vagal branch afferents and gastric vagal efferents in the brain. Considering this observation together with findings indicating that electrical stimulation of the proximal cut end of the hepatic vagal branch changes acidity in the gastric perfusing fluid or pressure within the stomach, it has been presumed that hepatic afferent signals related to glucose may regulate the motor or secretory function of the stomach through a change in central nervous activity. Recently active interaction between the portal and medullary glucose signals in gastric function was discovered, and analysis of the characteristic features of the system is in progress.

Gastric vagal fibres distribution and acid secretion induced by portal infusion of D-glucose

The vagal glucose signal pathway relevant to hepatic portal control of gastric acid secretion was examined in bilaterally adrenalectomized rats. The decrease in acid output after portal glucose injection was blocked by section of the hepatic branch which originates in the ventral vagus trunk below the diaphragm. After cervical vagotomy, the reduction in acid output was the same whether the section had been done on the right or the left side. The acid response was strongly inhibited by prior section of the dorsal vagus trunk at the celiac level. These results suggest that the hepatic glucose signal evoking an inhibitory action on the secretion of gastric acid has a specific pathway from the liver to the stomach, and that there is functional laterality in this pathway.

Gastric vagal functional distribution in the secretion of gastric acid produced by sweet taste

The sweet signal pathway relevant to lingual control of gastric acid secretion was examined in bilaterally adrenalectomized rats. The increase in the acid output after lingual glucose application was completely blocked by prior section of both sides of the vagus nerve at the cervical level. However, the reduction in the acid output showed no laterality following vagotomy on either side. At the subdiaphragmatic level, the acid response was mainly suppressed by section of the dorsal vagus trunk. Both sides of trunk vagotomy abolished the acid response. These results suggest that the sweet signal evoking gastric acid secretion has a specific pathway from the tongue to the stomach, and that there is functional laterality in this pathway in the visceral cavity.

Effects of D-glucose anomers on sweetness taste and insulin release in man

Insulin release was examined in human subjects after lingual applications of D-glucose and its anomers. A dose-dependent increase in the insulin release was noted following the application of equilibrated D-glucose consisting of 36% alpha- and 64% beta-anomer. The response was not reproduced after administration of atropine. The magnitude of insulin release produced by alpha-anomer was different from that induced by beta-anomer in men who could not differentiate between sweetness of the two anomers. Results indicate that recognition of sweetness in the cortex is unrelated to the insulin response, and suggest that a subcortical mechanism may detect qualitative differences in taste and produce the oral phase of insulin secretion via vagus action in humans.