Obesity alters adrenergic and chemosensory signaling pathways that regulate ghrelin secretion in the human gut

What is it about?

Humans are able to distinguish five basic tastes on the tongue: sweet, umami, salty, sour, and bitter. Recent evidence suggests that taste receptors are also expressed in extra-oral tissue where they regulate several biological functions. The gastrointestinal tract is the largest interface between the external environment and the body and senses the macronutrient composition of the meal to elicit adequate responses to assimilate (non)-nutrients from the food and to expel waste products and toxic compounds. As a sensory organ, it senses basic tastes in much the same way as the tongue, through the use of similar taste receptors. The present study investigates how bitter and sweet tastants regulate the secretion of the hunger hormone ghrelin in the gut mucosa of lean and obese subjects. Bitter tastants stimulate ghrelin secretion via several bitter taste receptors, while glucose inhibits ghrelin secretion via sweet taste receptors and the glucose transporter SGLT1. In addition, our findings showed that chronic overexposure of the gut to food, as in obese subjects, affects the sensitivity of taste receptors on the ghrelin cell in a region-dependent manner and impairs the sympathetic drive that controls ghrelin secretion. This study shows that taste receptors in the gut orchestrate gut hormone release and can be used as new therapeutic targets to regulate appetite.

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