Study reveals biology of leptin, the hunger hormone

cupcake
Credit: CC0 Public Domain

In a new study, Yale researchers offer insight into leptin, a hormone that plays a key role in appetite, overeating, and obesity. Their findings advance knowledge about leptin and weight gain, and also suggest a potential strategy for developing future weight-loss treatments, they said.

The study, led by investigators at Yale and Harvard, was published the week of June 17, 2019, in the journal PNAS.

Leptin, which is secreted by fat cells, informs the brain when fuel stored in body fat and in the liver is becoming depleted. It has not been well understood how low concentrations in plasma—the largest component of blood—increase appetite. The researchers studied the biology of leptin in rodents. They also investigated the influence of nerve cells in the brain known as AgRP neurons, which regulate eating behavior.

The researchers discovered that the mechanisms by which reductions in plasma leptin concentrations stimulate are not limited to the brain, as previously thought. In rodents, fasting first activates leptin receptors in the brain, followed by an intermediary step that involves the . This system includes the pituitary and , which secrete another hormone, , that regulates energy, stress responses, and food intake.

The research team learned that this chain of events is required for leptin to stimulate hunger when food is restricted, or when diabetes is poorly controlled and plasma leptin concentrations drop below a critical threshold, said Gerald Shulman, M.D., the George R. Cowgill Professor of Medicine at Yale School of Medicine, and co-corresponding author of the study.

In further experiments, the researchers also showed that plasma corticosterone activates AgRP neurons, which increases hunger when either leptin or blood-sugar levels are low, Shulman noted. In humans, leptin and blood sugar drop when people diet.

These findings add to scientists' knowledge of leptin, which has been the focus of research on obesity and weight loss since its discovery in the 1990s. The study reveals "the basic biology of leptin, and how the endocrine system is mediating its effect to regulate food intake under conditions of starvation and poorly controlled diabetes," said Shulman.

The research also lends support to a different strategy for developing drugs that treat obesity. "It suggests that AgRP neurons may be an attractive therapeutic target," he said.


Explore further

Leptin hormone spurs body's shift from burning carbs to fat

More information: Rachel J. Perry el al., "Leptin's hunger-suppressing effects are mediated by the hypothalamic–pituitary–adrenocortical axis in rodents," PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1901795116
Provided by Yale University
Citation: Study reveals biology of leptin, the hunger hormone (2019, June 18) retrieved 22 October 2019 from https://medicalxpress.com/news/2019-06-reveals-biology-leptin-hunger-hormone.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
190 shares

Feedback to editors

User comments

Jun 19, 2019
It would surprise me greatly if more than about 1 in 10 obese people ate because they felt hungry. In order to become obese you have to eat beyond what you body demands; you have to eat for reasons other than hunger. My guess is that the commonest drive to eat is anxiety caused by chronic hyperstimulation and hyperarousal.

Eating reliably lowers anxiety levels via the autonomic nervous system.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more