The hypothalamus via various mechanisms controls appetite and food intake. It is also responsible for the control of hunger and thirst. In the basal hypothalamus there are several nuclei that regulate daily energy homeostasis. These control the appetite.
Ingestion of food
Ingestion of food is particularly controlled by hypothalamic sites, such as the ventromedial nucleus (VMN), dorsomedial nucleus (DMN), paraventricular nucleus (PVN), and lateral hypothalamus (LH).
There are recent studies that have identified “orexigenic and anorexigenic neurotransmitters” in the hypothalamus. The orexigenic neurotransmitters increase appetite while the anorexigenic ones decrease appetite.
Parts of the hypothalamus related to appetite
Some parts of the hypothalamus are related to appetite. These include:
- The Arcuate nucleus – The arcuate nucleus (ARC) is located at the base of the hypothalamus. This has a high density of neurons that produce the orexigenic peptides, NPY (Neuropeptide Y), the opioids, dynorphin, and the POMC-derived peptide, β-endorphin, galanin, amino acids, γ-aminobutyric acid and glutamate.
- Ventromedial nucleus and lateral hypothalamus – It has been seen that any lesion in these areas leads to excessive appetite, and abnormal body weight gain that persist for a long time. These sites are said to possess a “satiety center” that constantly restrains the feeding.
- Dorsomedial nucleus – These areas when injected with orexigenic signals lead to excessive feeding.
- Paraventricular nucleus and perifornical hypothalamus – This region also has neuronal elements that control ingestive behavior. When injected with orexigenic signals, NPY, GAL, orexins, GABA, opioids, norepinephrine (NE), and epinephrine (E) this region is activated and leads to increased food intake. If injected with anorexigenic signals like CRH and leptin, this region leads to lowered feeding.
- Suprachiasmatic nucleus - The drive to eat is evoked by appetite or the sensation of hunger. This is based on the perception of the light-dark cycle. For example, rats consume between 85–90% of their total intake during dark periods. In humans signalling of appetite is linked to individual based requirements. These include neural, metabolic, and hormonal signals that tell a person it’s time to eat.