Ghrelin induces feeding in the mesolimbic reward pathway between the ventral tegmental area and the nucleus accumbens

Palatability Can Drive Feeding Independent of AgRP Neurons

“…We reasoned that in the absence of AgRP neurons, orexigenic drive might rely on dopamine tone because the ghrelin receptor is expressed in the VTA (Mani et al, 2014) where its activation has been shown to trigger feeding (Abizaid et al, 2006;Egecioglu et al, 2010;Jerlhag et al, 2007;Naleid et al, 2005). Control and AgRP-ablated mice were implanted with ICV and intra-VTA cannulas and feeding responses to ghrelin were monitored on chow or HFHS diet in presence or absence of [D-Lys3]-GHRP-6, a selective antagonist of the ghrelin receptor (Traebert et al, 2002) that is known to reduce food intake (Ishii et al, 2002).…”

“…Although the direct access of circulating hormones such as ghrelin or leptin to these structures lying away from blood brain barrier (BBB) entry point is still a matter of debate, injection of these hormones in the ventral tegmental area (VTA) or parabrachial nucleus (PBN) can inhibit feeding (Abizaid et al, 2006;Figlewicz et al, 2003;Fulton et al, 2006;Hommel et al, 2006;Jerlhag et al, 2007;Lee et al, 1998;Naleid et al, 2005 ;Quarta et al, 2009;Zigman et al, 2006). These observations raise the question of the specific contribution of ARC versus extra-ARC neurons in the balance between reward-driven or energy-driven nutrient intake.…”

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

“…Studies in rodents exploring the precise parenchymal targets for ghrelin's orexigenic effects have identified a number of candidate sites: orexigenic responses have been observed when injected into discrete brain areas that include the hypothalamus (arcuate nucleus, ventromedial nucleus, dorsomedial nucleus, paraventricular nucleus, lateral hypothalamus) (Olszewski et al 2003a;Olszewski et al 2003b;, the nucleus tractus solitarius of the brainstem (Faulconbridge et al 2003), the central nucleus of the amygdala (Olszewski et al 2003) and mesolimbic reward areas (the ventral tegmental area (VTA) and nucleus accumbens (N.Acc) Naleid et al 2005). Activation of hypothalamic and brainstem areas could be of importance for ghrelin's effects on homeostatic feeding that is driven by metabolic need.…”

“…Peripheral ghrelin appears to enhance sweet taste food consumption and preference, regardless of its caloric content (Disse et al 2010). Direct administration of ghrelin into the brain ventricles or into the VTA stimulates food intake, of both normal chow and palatable food (Abizaid et al 2006;Egecioglu et al 2010;Naleid et al 2005;Skibicka et al 2011a). Indeed, the fact that ghrelin can achieve this even in satiated animals suggested that the VTA is an important site for ghrelin's orexigenic effects.…”

The alcohol-induced locomotor stimulation and accumbal dopamine release is suppressed in ghrelin knockout mice

“…This gut-brain hormone also plays a role in brain reward and foodseeking behaviour (Naleid et al, 2005;Abizaid et al, 2006;Jerlhag et al, 2006;Jerlhag et al, 2007;Jerlhag et al, 2008;Jerlhag, 2008;Egecioglu et al, 2010).…”