Nutritive/non-nutritive sweeteners and high fat diet contribute to dysregulation of sweet taste receptors and metabolic derangements in oral, intestinal and central nervous tissues.

OBJECTIVES

Overconsumption of non-nutritive sweeteners is associated with obesity, whereas the underlying mechanisms remain controversial. This study aimed to investigate the effects of long-term consumption of nutritive or non-nutritive sweeteners with or without high fat diet on sweet taste receptor expression in nutrient-sensing tissues and energy regulation dependent on sweet-sensing.

METHODS

50 Male Sprague-Dawley rats (140-160 g) were assigned to 10 groups (n = 5/group). All received fructose at 2.5% or 10%, sucralose at 0.01% or 0.015% or water with a normal chow diet or high fat diet for 12 weeks. Food and drink intake were monitored daily. Oral glucose tolerance test and intraperitoneal glucose tolerance test were performed at week 10 and 11 respectively. Serum was obtained for measurement of biochemical parameters. Tongue, duodenum, jejunum, ileum, colon and hypothalamus were rapidly removed to assess gene expression.

RESULTS

Long-term consumption of sweeteners impaired glucose tolerance, increased calorie intake and body weight. A significant upregulation of sweet taste receptor expression was observed in all the four intestinal segments in groups fed 0.01% sucralose or 0.015% sucralose, most strikingly in the ileum, accompanied by elevated serum glucagon-like peptide-1 levels and up-regulated expression of sodium-dependent glucose cotransporter 1 and glucose transporter 2. A significant down-regulation in the tongue and hypothalamus was observed in groups fed 10% fructose or 0.015% sucralose, with alterations in hypothalamic appetite signals. The presence of high fat diet differentially modulates sweet taste perception in nutrient-sensing tissues.

CONCLUSIONS

Long-term consumption of whether nutritive sweeteners or non-nutritive sweeteners combined with high fat diet contribute to dysregulation of sweet taste receptor expression in oral, intestinal and central nervous tissues.