Ghrelin Modulates Brain Activity in Areas that Control Appetitive Behavior

Abstract

Feeding behavior is often separated into homeostatic and hedonic components. Hedonic feeding, which can be triggered by visual or olfactory food cues, involves brain regions that play a role in reward and motivation, while homeostatic feeding is thought to be under the control of circulating hormones acting primarily on the hypothalamus. Ghrelin is a peptide hormone secreted by the gut that causes hunger and food consumption. Here, we show that ghrelin administered intravenously to healthy volunteers during functional magnetic resonance imaging increased the neural response to food pictures in regions of the brain, including the amygdala, orbitofrontal cortex, anterior insula, and striatum, implicated in encoding the incentive value of food cues. The effects of ghrelin on the amygdala and OFC response were correlated with self-rated hunger ratings. This demonstrates that metabolic signals such as ghrelin may favor food consumption by enhancing the hedonic and incentive responses to food-related cues.

The role of the central ghrelin system in reward from food and chemical drugs

“…This hypothesis is substantiated further by human functional magnetic resonance imaging in which ghrelin administration to healthy volunteers altered the brain response to visual food cues in areas such as the ventral striatum (Malik 2008). Several studies have demonstrated an association between anomalous plasma ghrelin levels and aberrant eating patterns.…”

Brain Activation by Visual Food-Related Stimuli and Correlations with Metabolic and Hormonal Parameters: A fMRI Study

“…In the present study, we found a positive correlation between ghrelin and food-related activation in the insula areas bilaterally, as well as in the right hippocampus, during the fasting state although these associations did not reach significance. As ghrelin is the only orexigenic hormone [38,39] this association would be expected. Also, it is known to stimulate meal initiation, and receptors for ghrelin have been located in the hippocampus, arcuate nucleus and ventromedial hypothalamus.…”

Blockade of central nicotine acetylcholine receptor signaling attenuate ghrelin-induced food intake in rodents

“…It now seems clear that the orexigenic gastric-derived hormone ghrelin targets CNS circuits involved in both energy balance (Tschop et al, 2000) and reward (Jerlhag et al, 2006, Malik et al, 2008. Indeed, ghrelin appears to activate the midbrain dopamine neurons (Abizaid et al, 2006, Jerlhag et al, 2006 that form a key component of the reward system and include a prominent dopaminergic projection from the ventral tegmental area (VTA) to the nucleus accumbens (N.Acc.).…”