What Is the Connection Between Leptin and Obesity?
Leptin (LP) is a protein hormone secreted by adipose tissue. Humans generally believed that after entering the blood circulation, it will participate in the regulation of sugar, fat and energy metabolism, prompting the body to reduce food intake, increase energy release, inhibit the synthesis of fat cells, and then reduce weight.
Leptin
- Chinese name
- Leptin
- Foreign name
- Leptin
- Substance type
- Protein hormone
- Core efficacy
- Lose weight, control food intake, increase energy metabolism
- Alias
- Obesity hormone, leptin, anti-obesity factor
- Function
- Endocrinology, immune regulation, wound repair, etc.
- Leptin (LP) is a protein hormone secreted by adipose tissue. Humans generally believed that after entering the blood circulation, it will participate in the regulation of sugar, fat and energy metabolism, prompting the body to reduce food intake, increase energy release, inhibit the synthesis of fat cells, and then reduce weight.
- It is mainly produced by white adipose tissue. Its precursor is composed of 167 amino acid residues, and the N-terminal has a signal peptide of 21 amino acid residues. The signal peptide of this precursor is cut off in the blood to become 146 amino acids, and the molecular weight is 16KD, forming Leptin. Leptin has a wide range of biological effects, the more important of which is its role in the metabolic regulatory center of the hypothalamus, which exerts the effects of suppressing appetite, reducing energy intake, increasing energy expenditure, and inhibiting fat synthesis. Studies have shown that rats encoding the ob gene and lacking the ob gene have a strong appetite and a significant increase in weight, leading to pathological changes
- Leptin and obesity
- Scientists Douglas Gorman and Jeffrey Friedman from the United States in the 1960s and 1980s have devoted themselves to the research of related parties, and finally successfully solved the scientific mystery, so they became Oriental Nobel Called
- The function of leptin is multi-faceted, mainly in the regulation of fat and weight:
- 1. Inhibition of appetite: Leptin can significantly reduce human eating and reduce body weight and body fat content.
- 2. Increase energy consumption: Leptin can act on the center, increase sympathetic nerve activity, and convert a large amount of stored energy into thermal energy release.
- 3. Effect on fat synthesis: Leptin can directly inhibit fat synthesis and promote its decomposition, and some people think that it can promote fat cell maturation.
- 4. Impact on endocrine: Insulin can promote the secretion of leptin, which in turn exerts negative feedback regulation on insulin synthesis and secretion.
Leptin Leptin levels rise
- Causes leptin resistance and produces negative myocardial muscle strength. The level of leptin in plasma is usually positively correlated with changes in body weight, especially in the body. Clinically, obese patients often have different levels of blood leptin levels.
- Leptin
- The emergence of leptin resistance is directly caused by rising leptin levels in the circulation. As a very good analogy, the status of leptin resistance in obesity is similar to the role of insulin resistance in type 2 diabetes. Physiological level of leptin can cause vasodilation and has no significant effect on myocardial function, while pathological level of leptin can promote the production of a large number of oxidative free radicals, which in turn has a significant negative myocardial muscle effect. There is evidence that the negative myocardial muscle effect caused by leptin at the pathological level may be achieved by activation of the endothelin receptor (ET-1 Receptor) and its downstream reduced coenzyme (NAPDH) oxidase. Activation of NAPDH oxidase directly produces a large number of superoxide anions. These results have been confirmed in a db / db mouse model of excess leptin.
Leptin Leptin levels drop
- As a result, physiological regulation of leptin leads to a lack of regulation of cardiac function, leading to myocardial hypertrophy and low cardiac function, as opposed to up-regulation of leptin. Decreasing leptin levels can also directly contribute to the loss of leptin signaling, thereby causing physiological levels of leptin to affect the heart Functional regulation is missing. The author's laboratory has conducted in-depth research on obese ob / obese mice with hereditary leptin deficiency. The results showed that low levels of leptin led to significant obesity in mice (which weighed twice as much as wild-type mice), cardiac hypertrophy, decreased myocardial contractility, slowed contraction / diastolic rate, prolonged diastolic time, and disorders of myocardial calcium regulation Diverse heart function. Interestingly, leptin supplementation can significantly improve myocardial hypertrophy and cardiac hypofunction due to leptin deficiency, and at the same time have a significant inhibitory effect on weight gain.
- Further research results show that low levels of leptin directly cause a decrease in insulin sensitivity. The author's laboratory changed the structure of the insulin sensitizer chromium complex in 2007, and obtained a new chromium amino acid complex (has obtained a U.S. patent). We used this complex to prevent ob / ob leptin deficiency. Of obese mice underwent insulin sensitization. After 6 months of oral administration [45 g / (kg / d)], the myocardial function of ob / ob mice was significantly improved, and the calcium regulation disorder in myocardial cells was corrected, and the improvement of these myocardial function indicators was related to myocardial insulin The improvement in sensitivity coincides. From this point of view, whether the level of leptin rises or is absent, it can lead to disturbances in the regulation of body energy and fat metabolism by leptin, thereby contributing to the occurrence of obesity and eventually type 2 diabetes. However, a high-fat diet or excess nutrition can lead to a sharp rise in leptin levels and the leptin resistance caused by it, making leptin unable to normally complete the promotion of fat and energy metabolism and the related appetite suppression effect.
- Leptin regulates the body's body weight in both directions in the body, and is often referred to as a body fat homeostasis system. It can be understood that when the body's energy intake is positively balanced, body fat increases, which promotes increased secretion of leptin by adipocytes. Leptin acts on the hypothalamus and combines with its receptors to produce a satiety response, thereby reducing appetite and energy intake Promote energy consumption; When the body weight decreases, the secretion of leptin in adipose tissue decreases, which acts on another receptor in the hypothalamus, which produces a starvation response, increases appetite, increases food intake, and reduces energy consumption. In this way, the body weight should be kept within the normal range, why is there more and more obese people? This is the problem of leptin resistance. Although leptin is secreted a lot, it does not work. Most obese people have higher serum leptin levels than non-obese people; less than 5% of obese people have leptin deficiency. Most unfortunately, obese people not only show resistance to leptin in the body, but also have resistance to exogenous leptin. Therefore, the application of leptin in the treatment of obesity is still in the experimental stage.