Food reward

Introduction

Food intake is driven by both ‘homeostatic feeding’ (energy demands) and ‘non-homeostatic feeding’ (pleasure associated eating or preferred food). The latest is associated with the food reward processes, which is further categorized to’ liking’ (pleasure/palatability) and ‘wanting’ (incentive motivation) according to the Salience theory. Moreover, the salience model describes different brain mechanisms associated with each of the two components. Experiments using mouse model showed that the brain mechanisms attributed to ‘liking’ involve the neurotransmission of mu-opiods in the nucleus accumbens, ventral pallidum, parabrachial nucleus, and nucleus of the solitary tract, while mechanisms attributed to ‘wanting’ implicated the neurotransmitter dopamine secreted in brain areas such as the prefrontal cortex, amygdala, hypothalamus, and projections from the ventral tegmental area to the nucleus accumbens. Dopamine has an important role in both energizing feeding (secondary role) and also reinforcing feeding (primary role). The latest is associated with various food reward pathways of dopamine and that is where this article focuses the most on. The action of dopamine in dopaminergic systems is analysed, in addition interaction of dopaminergic system with other reward systems is described and finally the effect of other hormones such as insulin, ghrelin and leptin, on food reward is studied through their interaction with dopamine.