The researchers, led by Denis Burdakov from the University of Cambridge in the UK, compared how different nutrients affected orexin neurons, which secrete orexin/hypocretin, a stimulant known to affect wakefulness and how we use energy.
Glucose has previously been shown to lower the activity of orexin cells – which could lead to sleepiness and weight gain – but it was not clear whether the cells were affected by other macronutrients, they wrote. Burdakov and his colleagues tracked the cells’ responsiveness to protein in the form of an amino acid mix and found it stimulated greater orexin cell activity.
“What is exciting is to have a rational way to ‘tune’ select brain cells to be more or less active by deciding what food to eat,” Dr. Burdakov said in a university release. “Not all brain cells are simply turned on by all nutrients, dietary composition is critical.”
The researchers also found that the presence of amino acids prevented glucose from blocking the cells’ action, contrary to their hypothesis that protein and glucose would either cancel each other out or produce a net inhibitory effect, because the effect of glucose alone was greater than the stimulatory effect of protein alone.
Dr. Burdakov said: “To combat obesity and insomnia in today’s society, we need more information on how diet affects sleep and appetite cells. For now, research suggests that if you have a choice between jam on toast, or egg whites on toast, go for the latter! Even though the two may contain the same number of calories, having a bit of protein will tell the body to burn more calories out of those consumed.”
Vol. 72, pp. 616–629, November 17, 2011 DOI 10.1016/j.neuron.2011.08.027
“Activation of Central Orexin/Hypocretin Neurons by Dietary Amino Acid”
Authors: Mahesh M. Karnani, John Apergis-Schoute, Antoine Adamantidis, Lise T. Jensen, Luis de Lecea, Lars Fugger, and Denis Burdakov