Central Amino Acid Sensing in the Control of Feeding Behavior

Abstract

Dietary protein quantity and quality greatly impact metabolic health via evolutionary-conserved mechanisms that ensure avoidance of amino acid imbalanced food sources, promote hyperphagia when dietary protein density is low, and conversely produce satiety when dietary protein density is high. Growing evidence supports the emerging concept of protein homeostasis in mammals, where protein intake is maintained within a tight range independently of energy intake to reach a target protein intake. The behavioral and neuroendocrine mechanisms underlying these adaptations are unclear. While peripheral factors are able to signal amino acid deficiency and abundance to the brain, the brain itself is exposed to and can detect changes in amino acid concentrations, and subsequently engages acute and chronic responses modulating feeding behavior and food preferences. In this review, we will examine the literature describing the mechanisms by which the brain senses changes in amino acids concentrations, and how these changes modulate feeding behavior.

Feeding Stimulation Ability and Central Effects of Intraperitoneal Treatment of L-Leucine, L-Valine, and L-Proline on Amino Acid Sensing Systems in Rainbow Trout: Implication in Food Intake Control

“…Evidence so far in rainbow trout supports the notion that hypothalamic modulation of food intake through amino acid sensing systems responds to BCAA, and specifically to leucine, in fish as in mammals (Heeley and Blouet, 2016). This could be expected considering that in fish, just as in mammals, the highest correlation between dietary and postprandial systemic free amino acids composition is observed for essential amino acids (Jürss and Bastrop, 1995) and BCAA show the highest changes in plasma amino acid pool in periods of fasting as well as after feeding (Navarro et al, 1997).…”

Age dependent effects of protein restriction on dopamine release

“…The direct influence of protein or amino acids levels on dopamine neurons is still unexplored, however, these neurons receive input from hypothalamic regions which are able to detect amino acids [10,14]. Protein restriction also induces a broad metabolic response involving peripheral food-related signals to which dopamine neurons are directly sensitive [31][32][33][34][35].…”

“…Numerous species, including humans and rodents, regulate their food intake and food-related behaviors to avoid protein deficiency [8][9][10][11][12][13]. Increasing evidence implicates broad hypothalamic and limbic circuits in the regulation of protein appetite [10,[13][14][15].…”

Nutrient Sensing Systems in Fish: Impact on Food Intake Regulation and Energy Homeostasis

“…This process occurs through activation of amino acid sensing systems mediated by activation of target of rapamycin (mTOR) and/or inhibition of AMP-activated protein kinase (AMPK) signaling, or via activation of BCAA metabolism (Heeley and Blouet, 2016; Morrison et al, 2016). Furthermore, the deficiency in essential amino acids (including BCAA) elicits an increase in food intake through amino acid sensing systems mediated by general control nondepressable 2 and eukaryotic initiation factor 2α (Fromentin et al, 2012; Maurin et al, 2014).…”