Separate circuitries encode the hedonic and nutritional values of sugar

Abstract

Sugar exerts its potent reinforcing effects via both gustatory and post-ingestive pathways. It is however unknown if sweetness and nutritional signals engage segregated brain networks to motivate ingestion. We show in mice that separate basal ganglia circuitries mediate the hedonic and nutritional actions of sugar. We found that, during sugar intake, suppressing hedonic value inhibited dopamine release in ventral but not dorsal striatum, whereas suppressing nutritional value inhibited dopamine release in dorsal but not ventral striatum. Consistently, cell-specific ablation of dopamine-excitable cells in dorsal, but not ventral, striatum inhibited sugar’s ability to drive the ingestion of unpalatable solutions. Conversely, optogenetic stimulation of dopamine-excitable cells in dorsal, but not ventral, striatum substituted for sugar in its ability to drive the ingestion of unpalatable solutions. Our data demonstrate that sugar recruits a distributed dopamine-excitable striatal circuitry that acts to prioritize energy seeking over taste quality.

Physiology and assessment as low-hanging fruit for education overhaul

“…The result suggests that the positive cognitive effect of glucose intake is not simply due to its sweet flavor, of potential rewarding value, but in fact to the extra calories ingested. This aligns with recent evidence of separate circuits in mice for encoding the nutritional and hedonic values of sugar, with prioritization of energy-seeking over taste quality (Tellez et al 2016). …”

Nutritive, Post-ingestive Signals Are the Primary Regulators of AgRP Neuron Activity

“…This suggests that, devoid of all external sensory cues, nutrients have the ability to signal AgRP neurons along the gut-brain axis within seconds. Fast gut-brain signaling also occurs in central reward systems, which detect signals from sweet substances in the gastrointestinal tract within minutes (Tellez et al, 2016). However, these rapid effects on neural activity may require more time to influence behavior, as the emergence of taste preferences for caloric substances require ~30 minutes (Lucas and Sclafani, 1999).…”

Fructose metabolism and metabolic disease

“…Enhanced palatability may increase feeding behavior and thus encourage overeating (164). Moreover, fructose and sucrose can enhance palatability and induce addiction-like behaviors such as binging and dependence in part by stimulating dopaminergic pathways (165)(166)(167)(168). Distinct from fructose's hedonic value, whether fructose impacts additional signaling systems to regulate appetite and feeding behavior has also been studied.…”