In experimental model, disruption of Dh44 linked to failure to select nutritive sugars
TUESDAY, June 30, 2015 (HealthDay News) — Artificial sweeteners don’t contain the calories or energy that evolution has trained the brain to expect from sweet-tasting foods, thereby failing to satisfy hunger, and a specific hormone may be the key to the process, according to an experimental study published online June 11 in Neuron.
Monica Dus, Ph.D., from the California Institute of Technology in Pasadena, and colleagues examined the identity of the taste-independent nutrient sensor and mechanisms by which animals respond to the nutritional value of sugar in a Drosophila model.
The researchers found that nutritive sugars specifically activated six neurosecretory cells in the Drosophila brain, which produce Dh44, a homolog of the mammalian corticotropin-releasing hormone. Disruption of the activity of these neurons or expression of Dh44 correlated with failure to select nutritive sugars. A similar effect was seen with manipulation of the function of Dh44 receptors. Artificial activation of Dh44 receptor-1 neurons correlated with proboscis extensions and frequent excretion episodes. Decreased excretion was seen with reduced Dh44 activity.
“Together, these actions facilitate ingestion and digestion of nutritive foods,” the authors write. “We propose that the Dh44 system directs the detection and consumption of nutritive sugars through a positive feedback loop.”
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