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What Are the Features of Leptin?

Leptin is a protein hormone discovered in 1994 by researchers at Rockefeller University. The hormone was discovered while scientists were studying mice. It was found to play an important part in regulating energy -- both its expenditure and its intake. Leptin has received attention because of its impact on human beings, including its effects on reproduction, appetite and metabolism.

  1. Leptin Basics

    • Leptin is made up of amino acids, and the amount of leptin found in the body is proportional to the amount of body fat in an individual. Leptin receptors are located in the brain areas linked to the intake and expenditure of energy, and they act by controlling food intake and calorie-burning in concert with brain mechanisms in the hypothalamus. Leptin levels may decrease with lower levels of food consumption or from sleep deprivation.

    Relationship to Body Weight

    • Leptin has a role in the regulation of body weight. Studies have shown that leptin may provide a picture of the nutritional status of the body. Subjects with higher concentrations of leptin have been found to be heavier and research on mice demonstrated that those mice who received injections of leptin developed a suppressed appetite and a significant drop in body weight through reduced food intake and increased energy expenditure. Studies have shown that humans and animals with low body fat also have lower concentrations of leptin.

    Leptin and Reproduction

    • Leptin appears to have an effect on puberty. Studies using prepubescent mice who were dosed with leptin revealed that those mice reached reproductive maturity before others who were not dosed. The mice injected with leptin also began their reproductive cycles much earlier than other mice. In humans, individuals whose leptin receptors are not active do not reach puberty and are also obese. Leptin may play a significant role in puberty and reproductive development in both animals and humans.

    Leptin and Disease

    • Mice without leptin receptors or those whose leptin receptors do not work properly tend to have three times the body weight and five times the fat mass of those whose leptin receptors are functioning properly. Animal subjects that cannot process leptin are also prone to diabetes, weakened immune systems and infertility. However, in humans, malfunctions related to leptin are only a rare cause of severe obesity -- although such an effect does exist and can have dramatic consequences for significant human weight gain.

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