Studies Explore Leptin-Weight Link

WASHINGTON — Leptin, a hormone that affects weight and appetite, apparently helps wire the brain in ways that might set an animal on a lifetime path to slenderness or obesity, two teams of U.S. researchers said Thursday.

The studies, published in the journal Science, may take doctors a step closer to understanding whether leptin could be manipulated to help overweight people lose weight and keep it off.

The findings might also help explain why the food a person eats when very young, or even what a mother eats while pregnant, affects weight, heart disease and metabolism later in life.

And they help shed light on why it is so hard for many people to lose weight and keep it off.

In one study, a team from Rockefeller University and Yale University found that leptin affects both the physical structure and the function of neural circuits in the brain.

“This is a very dynamic effect that’s quite dramatic and somewhat surprising. In response to leptin, the cells create new connections,” said Rockefeller’s Dr. Jeffrey Friedman. “The malleability of these feeding circuits by leptin suggest the possibility that the brain’s wiring may be different in lean versus obese individuals.”

The researchers worked with specially bred mice, which are very similar to humans when it comes to basic biology.

In a second study in mice, scientists at Oregon Health & Science University found that exposure to leptin early in life affected brain structures involved in weight regulation.

“We’re excited about this finding because it shows how exposure to leptin can directly affect development of brain structures involved in regulating body weight,” the university’s Richard Simerly said.

“Our findings suggest a link between the developmental actions of leptin and early-onset obesity,” he added.