When scientists discovered leptin in 1994, it ushered in a new era of obesity research. Leptin's link to obesity was discovered when researchers noted that mice with a faulty leptin reception in their brains ate with abandon. When they improved sensitivity to leptin with therapy, the mice lost weight and became more physically active. Regulating leptin, therefore, may be an important part of treating the epidemic of obesity in the United States, but research is ongoing to explore just how leptin receptors work in human brains.
Identification
Leptin is a hormone that is produced by fat tissue and plays an important role in your body's constant attempt to maintain its energy balance. Produced while you're sleeping, leptin tells your brain when you are full and depresses your appetite so you will stop eating. Leptin comes from a Greek word meaning "thin," and scientists also refer to it as the "ob gene."
Function
Leptin works by crossing into the brain and binding to specific receptors. When they meet, your body releases chemicals and performs a number of functions, like increasing calorie burning, making your hungry or dulling your desire to eat more. The work of leptin receptors, thus, is instrumental in the development of obesity and eating disorders. There are a number of leptin receptors all over your brain, but scientists think the ones involved in eating and energy are located in the hypothalamus.
Leptin Resistance
Scientists initially thought having too little leptin was the reason most people experienced overweight and obesity. They soon discovered, however, that most obese people have high levels of leptin; they are just resistant to its effects. Research is still exploring whether the problem is in leptin getting to the brain or whether the receptors in the brain have trouble picking up and responding to leptin signaling. Having constant high levels of leptin is associated with obesity, as normally operating levels of leptin rise and fall. Reducing fat through increased physical activity and improved diet appears to make leptin receptors more sensitive to the hormone.
Research
Harvard University reports on a number of studies designed to treat obesity and related health problems through leptin. In one study, a group of mice were cured of diabetes by restoring the brain's sensitivity to leptin. Their activity levels also spontaneously doubled with this therapy, and scientists are hopeful this works the same way in people. Researchers reported in the October 2009 edition of the "Journal of Medical Investigation" that when leptin was injected directly into the brains of leptin-receptor-deficient mice, they lost weight and kept it off for the long-term. They also ate less. These discoveries may someday lead to treatments that resolve obesity due to problems with leptin receptors.
References
- Journal of Investigative Medicine: Central Leptin Receptor Action and Resistance in Obesity
- Journal of Clinical Investigation: Revisiting Leptin's Role in Obesity and Weight Loss
- Harvard Science: Shining Light on Leptin's Role in the Brain
- Harvard Focus: Leptin: No Pill Yet, but Plenty of Research to Swallow
- American Journal of Physiology: Leptin Resistance: A Prediposing Factor for Diet-Induced Obesity
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