Converging signals as we get ready to eat
Full4Health Partners at the University of Utrecht publish new study
Energy balance (energy consumed as food vs energy expenditure) is regulated by a network of brain areas, neurotransmitters and feeding hormones, but also by environmental stimuli. Cues that signal the availability of food (e.g. turning on a light or ringing a bell) are known to induce anticipatory behaviour. This may involve waking up, running around, preening or looking for food. Rats and humans may even start eating despite having satiated their appetite previously. It is thought that such food anticipatory behaviour prepares animals to make maximal use of available food. Unraveling what happens in the brain when food is expected is fundamental to our understanding of the mechanisms underlying obesity and eating disorders in humans.
The hypothalamus is an area of the brain known to regulate energy balance and mediate food anticipatory behaviour. This area is also responsive to feeding hormones. Ghrelin (increases food intake) and leptin (reduces food intake) are known to modulate nerve cell (neuronal) activity, feeding in general, and anticipation of food in particular. Exactly how the hypothalamus regulates food anticipatory responses is largely unknown.
The research team led by Prof. Roger Adan at the University of Utrecht wanted to know how feeding hormones regulate food anticipatory behaviour. Post-doctoral researcher Geoffrey van der Plasse examined brain activity in rats awaiting food. One particular neuronal cell population in the hypothalamus was seen to respond to both a cue signaling food delivery and to the hormone ghrelin. This convergence of environmental and hormonal signals at the level of individual brain cells with likely involvement in food anticipatory behaviour represents an important step in our understanding of processes within our brains when we are getting ready to eat.
Food cues and ghrelin recruit the same neuronal circuitry. International Journal of Obesity 2012 [Epub ahead of print] PMID 23069665