Leptin and obesity 指導：周淑娥教授、洪偉珊助教 組員： 57 陳昱愷、 60 陳重宇

Obesity When people take in excessive energy-rich molecules, they are converted to storage molecules. Order of storage: liver, muscle (glycogen) →adipose cells (fat) Order of expenditure ： liver → muscle, adipose cells Oil drops adipose cells nucleus

Diseases Obesity contributes to a number of healthy problems, including the common type of diabetes, cancer of colon and breast, and cardiovascular disease.

D.Coleman’s experiment In 1973, scientists discovered that mice with mutant ob gene or db gene eat voraciously and grow much more than normal mice. To explore the roles of genes, Coleman surgically linked mice’s circulatory systems.

In 1995, Jeffrey M. Friedman discover leptin and its role in regulating body weight. ob-deficient mice are injected with leptin and lose 30% weight. ob-deficient mice do not produce leptin. db-deficient mice are injected with leptin and have no change. db-deficient mice do not produce the receptor for leptin. Result

Leptin 由白色脂肪細胞所製造，作用至下視丘 刺激生熱效應 (thermogenesis) 、胰島素敏 感性、脂肪酸氧化作用，且降低食慾。 體內的脂肪越多，產生的 Leptin 就越多，來 抑制食慾，讓體重回到原來的體重。 Leptin (Greek leptos meaning thin) plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. The gene is located on chromosome 7 in humans. It is manufactured primarily in the adipocytes of white adipose tissue, and the level of circulating leptin is directly proportional to the total amount of fat in the body.

Leptin acts on receptors in the hypothalamus (1)counteracting the effects of neuropeptide Y (2) counteracting the effects of anandamid (3) promoting the synthesis of α-MSH, an appetite suppressant. This inhibition is long-term. The absence of leptin (or its receptor) leads to uncontrolled food intake and resulting obesity. function

Leptin resistance and obesity In general, obese people have an unusually high circulating concentration of leptin. These people are said to be resistant to the effects of leptin, in much the same way that people with type 2 diabetes are resistant to the effects of insulin. Fructose and leptin resistance A study suggests that the consumption of high amounts of fructose causes leptin resistance and elevated triglycerides in rats.

Conclusion As of today, there are at least five genes and ten kinds of hormones associated with the regulation of body weight. Reducing the intake of calorie and increasing the consumption of calorie is still the only feasible way to lose weight.