2Leptin and obesity昱愷

7/29/2019 2Leptin and obesity

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Leptin and obesity

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Obesity When people take in excessive energy-rich

molecules, they are converted to storagemolecules.

Order of storage: liver, muscle (glycogen)

adipose cells (fat)

Order of expenditureliver muscle, adipose

cells

Oil drops

adipose cells

nucleus


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Diseases

Obesity contributes to a number of healthyproblems, including the common type of

diabetes, cancer of colon and breast, and

cardiovascular disease.


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D.Colemans experiment

In 1973, scientists discovered that mice with

mutant ob gene ordb gene eat voraciouslyand grow much more than normal mice.

To explore the roles of genes, Coleman

surgically linked mices circulatory systems.


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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 leptinand have no change.

db-deficient mice do not produce the

receptor for leptin.

Result


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Leptin

Leptin (Greek leptos meaning thin) plays a keyrole 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 circulatingleptin is directly proportional to the total amount of

fat in the body.


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Leptin acts on receptors in the hypothalamus(1)counteracting the effects ofneuropeptide Y

(2) counteracting the effects ofanandamid

(3) promoting the synthesis of-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


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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.


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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.

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2Leptin and obesity昱愷