TY - JOUR
T1 - The brain's response to an essential amino acid-deficient diet and the circuitous route to a better meal
AU - Gietzen, Dorothy W.
AU - Aja, Susan M.
N1 - Funding Information:
Acknowledgements The tract-tracing work of Dr. Aja was supported by National Institutes of Health (NIH) grant DK 09271. DWG had support from NIH grants DK42274, NS 043210, and NS 33347, and from Ajinomoto Co., Inc., Tokyo. We extend particular thanks to Dr. Kunio Torii for his kind advice and collaboration. The authors are grateful to the many students and postdoctoral fellows and technicians in the Food Intake Laboratory at the University of California, Davis, who provided assistance with the animal and biochemical studies (to all those who weighed spill papers, special thanks). The authors extend our profound apologies to those whose volumes of work could not be included due to space limitations.
PY - 2012/10
Y1 - 2012/10
N2 - The essential (indispensable) amino acids (IAA) are neither synthesized nor stored in metazoans, yet they are the building blocks of protein. Survival depends on availability of these protein precursors, which must be obtained in the diet; it follows that food selection is critical for IAA homeostasis. If even one of the IAA is depleted, its tRNA becomes quickly deacylated and the levels of charged tRNA fall, leading to disruption of global protein synthesis. As they have priority in the diet, second only to energy, the missing IAA must be restored promptly or protein catabolism ensues. Animals detect and reject an IAA-deficient meal in 20 min, but how? Here, we review the molecular basis for sensing IAA depletion and repletion in the brain's IAA chemosensor, the anterior piriform cortex (APC). As animals stop eating an IAA-deficient meal, they display foraging and altered choice behaviors, to improve their chances of encountering a better food. Within 2 h, sensory cues are associated with IAA depletion or repletion, leading to learned aversions and preferences that support better food selection. We show neural projections from the APC to appetitive and consummatory motor control centers, and to hedonic, motivational brain areas that reinforce these adaptive behaviors.
AB - The essential (indispensable) amino acids (IAA) are neither synthesized nor stored in metazoans, yet they are the building blocks of protein. Survival depends on availability of these protein precursors, which must be obtained in the diet; it follows that food selection is critical for IAA homeostasis. If even one of the IAA is depleted, its tRNA becomes quickly deacylated and the levels of charged tRNA fall, leading to disruption of global protein synthesis. As they have priority in the diet, second only to energy, the missing IAA must be restored promptly or protein catabolism ensues. Animals detect and reject an IAA-deficient meal in 20 min, but how? Here, we review the molecular basis for sensing IAA depletion and repletion in the brain's IAA chemosensor, the anterior piriform cortex (APC). As animals stop eating an IAA-deficient meal, they display foraging and altered choice behaviors, to improve their chances of encountering a better food. Within 2 h, sensory cues are associated with IAA depletion or repletion, leading to learned aversions and preferences that support better food selection. We show neural projections from the APC to appetitive and consummatory motor control centers, and to hedonic, motivational brain areas that reinforce these adaptive behaviors.
KW - Anterior piriform cortex
KW - Essential amino acids
KW - Feeding circuits
KW - Foraging
KW - GCN2
KW - Hypothalamus
KW - Learned aversion
KW - Learned preference
KW - Nutrient sensing
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U2 - 10.1007/s12035-012-8283-8
DO - 10.1007/s12035-012-8283-8
M3 - Article
C2 - 22674217
AN - SCOPUS:84868155380
VL - 46
SP - 332
EP - 348
JO - Molecular Neurobiology
JF - Molecular Neurobiology
SN - 0893-7648
IS - 2
ER -