SGH THINK
[WAT & BAT]
What is adipose tissues? Anatomically, the adipose tissue is a connective tissue which is consisting mainly of fat cells. They are found mainly under the skin deposits between the muscles. And they are central metabolic organ in the regulation of whole body energy homeostasis. They secrete various hormones, cytokines, and metabolites that control systemic energy balance by regulating appetitive signals. In response to changes in the nutritional status, the adipose tissue undergoes dynamic remodeling. They change size, number something like that. There are three kinds of adipose tissues. BAT has more mitochondria and smaller lipid droplets. WAT has less mitochondria and bigger lipid droplet. First, Brown adipose tissue. Simply, BAT which generate body heat. They are critical for heat generation and lipid oxidation. So they have high mitochondrial density. Second one is Beige adipose tissue. It is result of ‘beiging’ remodeling from WAT to BAT phenotype. Beige adipose tissue is middle stage between BAT and WAT. Third one is white adipose tissue which is mainly talk today. WAT is a key energy reservoir for other organs.
Supraclavicular(쇄골) BAT and paravertebral(척추주변) BAT. They are core site of body thermal regulation. There are two main subtype of WAT. Visceral WAT, simply VAT which is concentrated in the abdominal cavity, Perirenal(신장주변), retroperitoneal(복막뒤), omental(장막), mesenteric(장간막), abdominal(복부), gluteal(둔근, 엉덩이부근), femoral(대퇴부) and subcutaneous WAT, simply SAT which do beiging remodeling. They do function as insulating layer.
Adipokine
Adipokines are cytokine which are chemical messengers produced by adipose tissue. Adipokines include inflammatory mediators, angiogenic proteins, and metabolic regulators. They are thought to influence multiple processes including macromolecules(glucose and fatty acid ) metabolism, regulation of apetite/satiety, and insulin sensitivity, and adipocyte differentiation. In addition to, they are also thought to serve as mediators linking obesity, inflammation, immunity and other obesity-related disease. First adipokine is leptin which is discovered by Friedman’s group in 1990. Leptin is one of the most well studied adipokine. Leptin is secreted in response to food intake and inhibits appetite by regulating neural circuits located in the brain. Leptin is opposed by the actions of the hormone ghrelin. Both act on surface receptors expressed in AGRP neurons in the lateral hypothalamus and POMC neurons in the medial hypothalamus. If we have lots of appetite, we would eat more food then free fatty acid and lipid deposition increase. Finally become more and more fat. How leptin affect to our body? At first appetite controlling by leptin. Adipocytes secrete Leptin. Leptin also regulate feeding and energy expenditure. Leptin through JAK/STAT pathway and MAP kinase cascade then inhibit leptin resistance. finally, energy expenditure is accelerated. If leptin or leptin receptors are mutation, are massively obese Because of uncontrolled appetite and ensuing excess food intake. Circulating leptin is actually elevated in obesity, but hypothalamic leptin resistance aggravates obesity through inhibition of appetite control and lipid oxidation. Second adipokine is adiponectin. Adiponectin is abundant in the blood. It exerts anti-obesity and antidiabetic effects and alleviates insulin resistance by stimulating lipid oxidation and anti-inflammatory responses. Two adiponectin receptors are AdipoR1 and AdipoR2. Both receptors stimulate AMPK(AMP-activated protein kinase) which is necessary for the anti-obesity and anti-diabetic actions of adiponectin. In obesity, circulating adiponectin are reduced. There are many other adiponectin. For example resistin, omentin, nesfatin and so on. Nowaday, many scientist in this field, are studying them.
[Obesity]
Obesity is medical condition in which excess body fat. WHO said obesity are defined as abnormal or excessive fat accumulation that presents a risk to health. Obesity can cause many other critical disease. So WHO declare a war to obesity. Obesity is defined by BMI, which is measured by weight over height. According to research of obesity which name is “The state of obesity”, In USA, there are 34.9% of adults are obesity, and 68.5% of adults are obesity or overweight in 2011 to 2012. In addition, According to research by National cancer center of Korea, There are almost 31% of adults are obesity, and almost 50% of adults are obesity or overweight in 2011 to 2012. I think BMI have some unclear point. so In my opinion, There are three major hot spot of fat in our body. Arm, belly, and thighs. by measuring thickness of arm, belly, things then compute this modification.
[(Thickness of arm X 3) + (Belly fat) + (Thighs X 2)]/3
