Leptin

Definition

Leptin is a hormone primarily produced by adipose (fat) tissue that plays a crucial role in regulating energy balance, appetite, and metabolism. It signals the brain about the body's energy reserves, helping to control hunger and promote energy expenditure. As body fat increases, leptin levels rise, which typically reduces appetite and increases energy use, contributing to maintaining body weight.

5 Must Know Facts For Your Next Test

1. Leptin was discovered in the 1990s and is often referred to as the 'satiety hormone' because of its role in signaling fullness to the brain.
2. In individuals with obesity, leptin levels can be high, but the body may become resistant to its effects, leading to continued hunger and reduced energy expenditure.
3. Leptin not only influences appetite but also plays a role in regulating reproductive function, immune responses, and bone metabolism.
4. Leptin levels fluctuate throughout the day and are influenced by factors such as sleep, stress, and diet.
5. Research has shown that leptin can affect physical activity levels by increasing energy expenditure and promoting fat oxidation.

Review Questions

• How does leptin interact with the hypothalamus to regulate appetite and energy balance?
  • Leptin interacts with receptors in the hypothalamus to signal satiety and regulate energy balance. When fat stores increase, leptin levels rise and bind to these receptors, triggering pathways that suppress appetite and promote energy expenditure. This signaling helps the body maintain homeostasis by balancing food intake with energy needs.
• Discuss how leptin resistance can contribute to obesity and its implications for weight management strategies.
  • Leptin resistance occurs when high levels of leptin fail to effectively signal satiety to the brain, often seen in individuals with obesity. This condition can lead to persistent hunger and decreased energy expenditure, complicating weight management efforts. Understanding leptin resistance is critical for developing effective interventions aimed at regulating appetite and restoring sensitivity to this hormone.
• Evaluate the broader physiological roles of leptin beyond appetite regulation, including its impact on metabolic processes and overall health.
  • Beyond regulating appetite, leptin has significant impacts on various metabolic processes such as glucose homeostasis, lipid metabolism, and even immune function. Leptin influences reproductive health by affecting hormone levels related to fertility. Its multifaceted roles highlight the importance of maintaining proper leptin signaling for overall health and disease prevention, particularly in conditions like obesity, diabetes, and cardiovascular diseases.

Related terms

ghrelin:

A hormone produced in the stomach that stimulates appetite and promotes food intake, often referred to as the 'hunger hormone'.

adipose tissue: A type of connective tissue that stores fat and is involved in regulating energy balance, metabolism, and hormone production.

hypothalamus: A region of the brain that plays a key role in maintaining homeostasis, including regulating hunger, thirst, and energy balance.