What Are Adipocytes?

Adipocytes in the human body can be divided into white and brown adipocytes. The two types of adipocytes are very different in morphology, function and origin. ^[1]

The body's weight is determined by the number and size of adipocytes. each

The main physiological function of fat cells in the body is to store them in the form of triglycerides and supply energy when the body needs them. The anabolic metabolism of adipocytes mainly includes two processes of absorption and synthesis. Triglycerides can be broken down by intestinal mucosal cells into glycerol and fatty acids, and enter the blood circulation through the portal vein. Apolipoproteins bind into chylomicrons and enter the blood circulation through the lymphatic vessels. ^[1]

Modern research shows that adiponectin is the most abundant protein hormone secreted by adipocytes, accounting for 0.01% of total plasma protein. Studies have shown that adiponectin can promote glucose absorption and inhibit liver glucose output through receptors present in liver and skeletal muscle cells, and stimulate the oxidative utilization of fat, thereby directly improving glucose and lipid metabolism.

Adiponectin can also inhibit atherosclerotic cell changes in various ways, such as inhibiting TNF2A-induced NF2JB activation by promoting IJB phosphorylation! Inhibiting the expression of adhesion factors, reducing monocyte adhesion to endothelial cells, inhibiting foam cell formation, and Proliferation and migration of smooth muscle cells. When vascular disease occurs, adiponectin can be deposited on the damaged blood vessel wall, playing the role of firefighter and protecting the vascular endothelium. Therefore, adiponectin has anti-IR, anti-atherosclerosis and anti-inflammatory effects, and has important prospects for drug development. ^[2]

Unlike other adipokines, adiponectin levels are lower in obese people; hypoadiponectinemia is also closely related to IR, dyslipidemia, and the inflammation marker CRP, and is considered a biochemical marker of MS. Genetic studies have also confirmed that the adiponectin gene is located at a chromosomal site (3q27) linked to DM and found that its genetic polymorphism is related to the phenotype of MS. It has been found that insulin sensitizers can promote adiponectin production; fat reduction through gastric volume reduction surgery can increase adiponectin levels to normal. ^[1]

Adipocytes also have complete renin-2 angiotensin system (RAS) activity. Secreted angiotensin is an important peripheral source. The produced RAS peptides can regulate the differentiation and growth of adipocytes, and can also affect blood vessels and Separating organs, regulating blood pressure, and cardiovascular response in obese individuals may play an important role in the development of obesity-related hypertension. At the same time, adipose tissue is the main source of increased PAI21 in the circulation. PAI21 can limit the excessive growth of adipose tissue, and it is also related to the abnormal coagulation and fibrinolysis in obese people. ^[2]

In short, when obese, especially abdominal obesity, the expression of adipose factor in adipose tissue changes, which is manifested by increased blood FFA, increased PAI21, hyperleptinemia, and reduced anti-inflammatory and anti-IR adiponectin secretion. And many inflammatory cytokines increase, activate inflammatory signaling pathways, induce a large number of inflammatory mediators, put the body in a chronic inflammatory state, and jointly lead to the occurrence of IR and MS. ^[2]