The Control of Appetite

1. Introduction
2. Stimulating Appetite
3. Suppressing Appetite
4. Quiz

• Appetite is controlled by the arcuate centre in the hypothalamus
• Excitatory neurones act to stimulate appetite, and inhibitory neurones act to suppress appetite
• There are many peptide hormones involved in appetite control, including neuropeptide-Y, agouti-related peptide, POMC, ghrelin, and PYY
• Ghrelin is released in response to an empty stomach to stimulate appetite
• Leptin and PYY both act to suppress appetite

Introduction

Appetite is controlled by the arcuate centre in the hypothalamus which prompts feelings of hunger. There is also a satiety centre, which controls the feeling of ‘fullness’, helping to regulate the amount of food intake, and timing of food intake.

The arcuate centre contains primary neurones that sense metabolite and hormone levels. Secondary neurones in other areas of the hypothalamus receive inputs from these arcuate primary neurones, and co-ordinate an appropriate response via autonomic and neuroendocrine pathways, including vagal signalling.

The primary neurones in the arcuate nucleus can be sub-divided into excitatory neurones and inhibitory neurones.

• Excitatory neurones: stimulate appetite via the release of neuropeptide-Y and agouti-related peptide.
• Inhibitory neurones: supress appetite via the release of POMC (pro-opiomelanocortin).

POMC is a polypeptide prohormone, which can be cleaved to produce several peptide hormones (β-endorphin, ACTH, α-MSH).

• α-MSH acts on melanocortin-4 receptors to supress the appetite.
• β-endorphins create the reward systemin the brain which produces feelings of euphoria and tiredness in response to eating.

Some regions of the brainstem are also involved in appetite control, but this will not be discussed in this article.

Stimulating Appetite

When our stomach is empty, ghrelin (a peptide hormone) is released from the stomach wall, which activates the stimulatory neurones in the arcuate nucleus, which stimulates the appetite. Once eating occurs (in response to the increased appetite), stretch of the stomach wall caused by the food intake inhibits ghrelin release.

Preview the Control of Appetite quiz