Question

Contrast the neural pathways mediating “hedonic” drive for food intake with the “homeostatic” neuroendocrine pathways maintaining stable body weight.  How do these pathways interact?

Answer 1

The hedonic and neuro endocrine homeostasis works together to maintain a healthy weight. Hedonic pathway causes desire to consume food even during abundance energy resources in response to highly palatable food items. Neuroendocrine homeostasis stimulates the desire to eat food when energy sources in the body starts depleting. But both the pathways have many differences.

Hedonic pathway : Highly palatable food items stimulates mesolimbic dopamine pathway. The dopamine is released from dopamine neurons. It is believed that orexin neurons release orexin which stimulates release of dopamine from ventral tegmental area. The dopamine then acts on nucleus accumbens of the ventral striatum. The nucleus accumbens release GABAergic projections that act on hypothalamus to increase desire to consume food.
Neuroendocrine pathway : The two hormones leptin and ghrelin control this pathway. When the body has abundant food resources leptin is released which suppresses the desire to food intake and stimulates metabolic processes. On the other hand ghrelin is stimulated when the body energy stores deplete and stimulates food intake.
Leptin acts on arcuate nucleus which causes inhibition of desire for food intake. Ghrelin acts on arcuate nucleus which stimulates desire for food intake.
Interaction of hedonic and neuroendocrine pathway : It is believed that leptin secretion causes feeding related dopamine release from VTA and basal secretion which suppresses the desire for food intake. On the other hand decreased Leptin levels cause VTA stimulation to release dopamine that stimulates food intake desires.