Ghrelin

Definition

Ghrelin is a hormone primarily produced by the stomach that stimulates appetite and regulates energy balance in the body. It is considered the counterpart to leptin, which suppresses appetite.

5 Must Know Facts For Your Next Test

1. Ghrelin levels rise before meals and fall after eating, signaling hunger and stimulating food intake.
2. Ghrelin acts on the hypothalamus to increase the production of orexigenic (appetite-stimulating) neuropeptides like NPY and AgRP.
3. In addition to regulating appetite, ghrelin also influences growth hormone release, gastric acid secretion, and gastrointestinal motility.
4. Ghrelin levels are typically higher in individuals with anorexia nervosa and lower in those with obesity, reflecting its role in energy homeostasis.
5. Disruptions in ghrelin signaling have been implicated in the development of metabolic disorders like obesity and type 2 diabetes.

Review Questions

• Explain the role of ghrelin in the central control of appetite and energy balance.
  • Ghrelin is a key player in the central control of appetite and energy balance. As a hormone primarily produced by the stomach, ghrelin levels rise before meals and fall after eating, signaling hunger and stimulating food intake. Ghrelin acts on the hypothalamus to increase the production of orexigenic (appetite-stimulating) neuropeptides like NPY and AgRP, which promote appetite and food-seeking behavior. This helps to regulate energy homeostasis by ensuring the body receives the necessary nutrients and energy. Disruptions in ghrelin signaling have been linked to the development of metabolic disorders like obesity and type 2 diabetes.
• Describe the relationship between ghrelin and leptin in the context of energy balance regulation.
  • Ghrelin and leptin act as counterparts in the regulation of energy balance. Ghrelin is considered the 'hunger hormone' as it stimulates appetite and food intake, while leptin is the 'satiety hormone' that signals the brain to reduce appetite and increase energy expenditure. Ghrelin levels rise before meals and fall after eating, while leptin levels are higher when energy stores are abundant and lower when they are depleted. This dynamic interplay between the two hormones helps to maintain energy homeostasis by balancing hunger and satiety signals. Disruptions in this delicate balance, such as leptin resistance or alterations in ghrelin signaling, can contribute to the development of metabolic disorders.
• Analyze the potential therapeutic applications of targeting ghrelin or its signaling pathways in the management of obesity and related metabolic conditions.
  • Given ghrelin's central role in regulating appetite and energy balance, targeting ghrelin or its signaling pathways has emerged as a promising therapeutic strategy for the management of obesity and related metabolic conditions. Approaches may include the development of ghrelin receptor antagonists or agonists, as well as the modulation of ghrelin-producing cells or enzymes involved in ghrelin synthesis and degradation. By counteracting the orexigenic effects of ghrelin, these interventions could help reduce food intake, promote weight loss, and improve metabolic parameters in individuals with obesity, type 2 diabetes, and other metabolic disorders. However, the complexity of the ghrelin system and its interactions with other hormones and neural pathways involved in energy homeostasis must be carefully considered to ensure the safety and efficacy of any therapeutic targeting of the ghrelin axis.

Related terms

Leptin:

A hormone produced by adipose tissue that signals the brain to reduce appetite and increase energy expenditure, acting as an antagonist to ghrelin.

Orexin: A neuropeptide that promotes wakefulness and arousal, and also interacts with ghrelin to regulate appetite and energy homeostasis.

Neuropeptide Y (NPY): A neurotransmitter that stimulates appetite and is influenced by ghrelin, playing a role in the central control of energy balance.