Fasting upregulates PPARγ in adipocyte AMPK activated
Adipose
Structure and Function
There are two categories of human adipose tissue, subcutaneous adipose tissue (SCAT) and visceral adipose tissue (VAT). Adipose tissue can be further classified as white adipose tissue (WAT) and brown adipose tissue (BAT). Adipose is composed of adipocytes, pre-adipocytes, fibroblasts, and immune cells. A vascular network runs through adipose while nerves innervate the tissue as well. Adipocytes found in WAT contain a single large lipid droplet which is considered an organelle. The nucleus and other organelles are displaced to the side of the adipocyte close to the membrane [1].
BAT functions in heat production through thermogenesis. WAT comprises the majority of adipose found in adults. WAT adipocytes store fatty acids (FA) esterified with glycerol in the form of triacylglycerols (TAG). Circulating FAs are attached to lipoproteins are transported into adipocytes via lipoprotein lipase. Glucose and other non-lipid entities may be converted into lipids via lipogenesis within adipocytes. Adipocytes also serve an endocrine function secreting adipocytokines such as adiponectin, leptin and resistin [1].
Under a fasted state adipocytes respond to a high glucagon:insulin ratio by hydrolyzing TAGs into free FAs and glycerol. The FAs may be taken up by other cells and used to produce energy through β-oxidation within the mitochondrial matrix. The glycerol may enter gluconeogenesis [1].
Add a brief synopsis of what happens with pre-adipocytes and adipogenesis under fasted condtions
AMPK
Structure and Function
Adenosine monophosphate kinase (AMPK) is considered the energy sensor of cells. When AMPK is activated under conditions of low intracellular energy ...
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...ts and other data. Fasting for 15 hours increases the AMP/ATP ratio in adipocytes. The binding of AMP to AMPKγ allows for LKB1 to phosphorylate AMPKα Thr172. Activated AMPK may phosphorylate eIF2α rendering it inactive. PPARγ mRNA may continue to be transcribed, but it cannot be translated while eIF2α is inactive meaning less PPARγ is expressed. Less C/EBPα mRNA is translated as well due to inactivated eIF2α. A reduction in PPARγ translates to a decrease in C/EBPα activation and the feed forward loop between these complexes is also reduced. Under fasted conditions adipocytes are attempting to conserve energy by down-regulating anabolic processes such as lipogenesis through the down-regulation of lipogenic initiation factors such as PPARγ.
There is sufficient evidence both in vitro and in vivo to conclude that fasting down-regulates PPARγ in adipocyte AMPK activated.
The ATP is used for many cell functions including transport work moving substances across cell membranes. It is also used for mechanical work, supplying the energy needed for muscle contraction. It supplies energy not only to heart muscle (for blood circulation) and skeletal muscle (such as for gross body movement), but also to the chromosomes and flagella to enable them to carry out their many functions. A major role of ATP is in chemical work, supplying the needed energy to synthesize the multi-thousands of types of macromolecules that the cell needs to exist. ATP is also used as an on-off switch both to control chemical reactions and to send messages.
In this experiment mice were studied as examples of organisms that employ physiological mechanisms to maintain and regulate internal body temperature.
Glucose consumption in the tissues and glucose production are balanced when the body is at rest. At the start of exercising the energy the body gets quickly is from the anaerobic metabolism using mostly muscle glycogen...
This is monitored by the cells within the Islets of Langerhans, which is located in the control (the pancreas). After skipping a meal or tough physical exercise blood glucose concentration decreases. Alpha cells in the islets detect this drop and are stimulated to secrete glucagon. Glucagon is a polypeptide hormone which influences an increase in blood glucose concentration. Glucagon travels through the bloodstream until it reaches glucagon receptors which are predominantly found in the liver, as well as, the kidneys. Glucagon stimulates the breakdown of stored glycogen to be released into the bloodstream as glucose. It also stimulates the conversion of amino acids into glucose and the breakdown of fat into fatty acids. These effectors cause an increase in blood glucose levels back towards the normal. This increase in blood glucose concentration is detected by the alpha cells which then stop the secretion of
According to Lewis and associates, DM is a chronic disease that affects multiple body systems. For the purpose of this paper, only DM type 2 will be discussed based on the assumption that a majority of patients aged 60 years or older have this type. The primary defects of this disease consist of insulin resistance, decreased insulin production, inappropriate glucose production by the liver, and alterations in production of adipokines. Insulin resistance is the result of defects in the body’s insulin receptors. This finding predates all cases of DM type 2 and the development of impaired glucose tolerance. In insulin resistance, beta cells in the pancreas are stimulated to increase insulin production to compensate for the lack of response by the insulin receptors. Gradually, the beta cells begin to fail to secrete enough insulin to meet the body’s demands resulting in hyperglycemia. As a result of increased glucose in the liver, the liver begins to malfunction and release glucose at inappropriate times, thereby worsening hyperglycemia. Adding to the problem, glucose and fat metabolism is altered in adipose tissue, which is generally abundant in those with DM type 2. (Lewis et al., 2011)
Lipid metabolism is one source of energy for the human body. We eat food containing one form of lipids, triacylglycerols. Before starting lipid metyabolism, these fats get broken down into droplets by bile salts.Triacylglycerols can be broken into fatty acids plus glycerol via hydrolysis with the help of the pancreatic lipase enzymen and then get used by cells for energy by breaking down even further. Once the pancreas and cells have enough energy and don’t need to absorb anymore, fatty acids get synthesized back into triacylgleryols. The excess triacylglycerols get stored in adipose tissue. Excess storage leads to weight gain and obesity.
Scientist have been researching cellular respiration “They discovered that when Stat 3 protein was missing, cells consumed less oxygen and produced less ATP, the key molecular form of cellular energy,” which means that the ene...
Sethi, J. K., Vidal-Puig, A. J., (2007). Targeting fat to prevent diabetes. Cell Metab. . 5 (5), 357-70.
In order for the body to maintain homeostatic levels of energy, blood glucose regulation is essential. Glucose is one of the body’s principal fuels. It is an energy-rich monosaccharide sugar that is broken down in our cells to produce adenosine triphosphate. In the small intestine, glucose is absorbed into the blood and travels to the liver via the hepatic portal vein. The hepatocytes absorb much of the glucose and convert it into glycogen, an insoluble polymer of glucose. Glycogen, which is stored in the liver and skeletal muscles, can easily be reconverted into glucose when blood-glucose levels fall. All of the body’s cells need to make energy but most can use other fuels such as lipids. Neurons; however, rely almost exclusively on glucose for their energy. This is why the maintenance of blood-glucose levels is essential for the proper functioning of the nervous system.
It is only in this pathway where fat can be used for energy. Exercises utilizing this
Tremblay, A., Simoneau, J., & Bouchard, C. (1994). Impact of exercise intensity on body fatness and skeletal muscle metabolism. Metabolism, 43(7), 814--818.
The absorptive state is the time during and right after eating a meal. The absorptive state lasts for four hours, during and after each meal. During this state glucose is the most important energy fuel. Amino acids and fats are used to form degraded protein, and small amounts are used to provide ATP. Metabolites are transformed to fat if they are not used for anabolism. Glucose is formed by the conversion of fructose and galactose, which are stored in the liver from the entrance of monosaccharides. Glucose is released into the blood, or converted to glycogen and fat. Some glucose enters the liver and is used for energy, and any that is not used will be stored in skeletal muscle as glycogen or in adipose cells as fat. Liver, skeletal muscle, and adipose cells use triglycerides as their primary energy source. Amino acid are also used by the liver to synthesize plasma proteins. Essentially all of the events that occur in the absorptive state are directed by insulin.
Immediately after a high carbohydrate meal, Insulin secrets rapidly due to glucose absorption into blood. This insulin act on many tissues in body and insulin turn causes rapid uptake, storage and use of glucose almost all issues of the body, but especially by the muscles, adipose tissue and liver. (8)
When fasting your body eats fatty acids, and ketone bodies, which then release energy in the process.
Body composition is one of the five health related fitness components and it is the percent body fat, bone, water and muscle found in your body. Although fat is associated with negative connotations, it has important functions in our body such as the cushioning of organs, shock absorption and temperature regulations. This ‘positive’ fat is known as essential fat, and the ‘negative’ fat is known as nonessential fat. The percent body fat is used to determine the total fat found in your body and it is based on gender and size of each individual. In the textbook “Concepts of Physical Fitness: Active Lifestyle for Wellness” by Corbin, he states that fat location influences health risk; based on where the fat is located you could be considered an apple or a pear. A person considered an apple has fat in the upper body. This is often found in men and in menopausal women. A pear shape, which is most common in women than men, has more fat located in the hips and upper legs. Corbin defines visceral fat as fat located at the core of the body (abdominal cavity), and subcutaneous fat as fat located under the skin.