Ghrelin

Definition

Ghrelin is a hormone produced mainly in the stomach that stimulates appetite and promotes food intake. Often referred to as the 'hunger hormone,' it plays a key role in energy balance and metabolic regulation by signaling the brain to initiate feelings of hunger when the stomach is empty.

5 Must Know Facts For Your Next Test

1. Ghrelin levels increase before meals and decrease after eating, indicating its role in meal initiation.
2. It not only stimulates appetite but also influences the secretion of growth hormone from the pituitary gland.
3. Ghrelin interacts with neuropeptide Y and agouti-related peptide in the hypothalamus to enhance hunger signals.
4. Chronic stress can lead to elevated ghrelin levels, which may contribute to stress-induced eating behaviors.
5. Research suggests that ghrelin may also have roles in regulating sleep, mood, and cognitive functions.

Review Questions

• How does ghrelin influence hunger and appetite regulation in the body?
  • Ghrelin plays a crucial role in hunger regulation by signaling the brain when the stomach is empty. As its levels rise before meals, it activates appetite centers in the hypothalamus, leading to increased food intake. After eating, ghrelin levels decrease, signaling satiety. This cycle of ghrelin secretion is essential for maintaining energy balance.
• Compare and contrast the roles of ghrelin and leptin in appetite regulation.
  • Ghrelin and leptin are key hormones in appetite regulation but function oppositely. Ghrelin is known as the 'hunger hormone,' increasing appetite and food intake when levels are high. In contrast, leptin is produced by fat cells and signals satiety, suppressing hunger when energy stores are sufficient. Together, these hormones work to maintain energy homeostasis by balancing hunger and satiety signals.
• Evaluate the impact of ghrelin on metabolism and potential implications for obesity treatment strategies.
  • Ghrelin significantly impacts metabolism by influencing appetite and energy balance, making it a target for obesity treatments. Elevated ghrelin levels can lead to increased food consumption, promoting weight gain. Understanding ghrelin's mechanisms could help develop therapies that block its action or reduce its production, potentially aiding in weight management and obesity prevention strategies.

Related terms

Leptin: A hormone produced by adipose (fat) tissue that helps to regulate energy balance by inhibiting hunger, counteracting ghrelin's effects.

Hypothalamus: A region of the brain that regulates various bodily functions, including hunger, thirst, and energy homeostasis, acting as a central hub for ghrelin signaling.

Energy Homeostasis: The balance between energy intake through food consumption and energy expenditure through metabolic processes and physical activity.