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Endocrine system&Obesity

By Gladys White,2014-01-13 08:52
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Endocrine system&Obesity

生命科学学院 2011 生命科学与技术基地班 胡升 1142043040

    Endocrine system&Obesity

    HuSheng 1142043040

    Background:

    There is an epidemic of overweight and obesity worldwide. Like hypertension or diabetes, obesity is a chronic disease.Obesity is associated with significant disturbances in endocrine function.

    Hyperinsulinemia and insulin resistance are the best known changes in obesity, but their mechanisms and clinical significance are not clearly established. Adipose tissue is considered to be a hormonesecreting endocrine organ; and increased leptin secretion from the adipocyte, a satiety signal, is a well-established endocrine change in obesity. In obesity there is a decreased GH secretion. The pathophysiological mechanism responsible for low GH secretion in obesity is probably multifactorial. In women, abdominal obesity is associated to hyperandrogenism and low sex hormone-binding globulin levels.Obese men, particularly those with morbid obesity, have decreased testosterone and gonadotropin levels. Obesity is associated with an increased cortisol production rate, plasma free cortisol levels do not change when body weight increases. Ghrelin is the only known circulating orexigenic factor, and has been found to be decreased in obese people. In obesity there is also a trend to increased TSH and free T3 levels.

    This article on obesity in the main effect of endocrine pancreas, adipose tissue, pituitary gland, gonads, adrenal glands,gastrointestinal hormones and thyroid gland.

    1.Endocrine pancreas

    The endocrine pancreas is a secretory gland with several functions, the two important are endocrine and exocrine.The main components of the exocrine are pancreatic juice, and the main components of the endocrine are insulin and glucagon.The most notable features of endocrine change is increased insulin levels caused by obesity.Obesity can also lead to insulin resistance by mechanism of endocrine, inflammatory reaction,oxidative stress and functional disorder of adipose cell.

    2.Adipose tissue

    Adipose tissue expressions and secretes lots of biologically active peptides called fat factors.These factor paly a role at partial and systemic levels.Leptin is one of the fat factors.Which is considered to be a satiety signal, can motive the satiety center the reduce the eating.Adiponectin is an protein secreted by adipose cell, studies have found an inverse correlation between the adiponectin level in plasma and body fat content.Resistin and obesity are closely related,resistin can increase the number of adipose cell or gather the volume of adipose cell.

    3.Pituitary gland

    The study found that GH which secreted by pituitary gland and obesity are closely related.GH plays a role at liver and adipose tissue.The study also found that GH can influence fat factors likes leptin and adiponectin.Obesity lead to decrease GH levels in body.

生命科学学院 2011 生命科学与技术基地班 胡升 1142043040

    4.Gonads

    In women, as the growth of the age, the function of the ovaries gradually decline, leading to the obesity and insulin resistance.Studies have found an inverse correlation between the hormone level and abodominal organs fat content.When the estrogen level decrease to a certain level, the abodominal organs fat content began to accumulate.This phenomenon may be related to the action of estrogen.Especially, the same of lutin, androgen and estrogen, they express at adipose tissue.Subcutaneous adipose tissue has a high density of estrogen and progesterone receptors, while visceral fat has a high density of androgen receptors.Besides, subcutaneous adipose tissue has a very low level of androgen, estrogen can influence the expression of androgen at subcutaneous adipose tissue.

    Obese men, particularly those with morbid obesity, have decreased testosterone and gonadotropin levels.Male obesity is related to the decrease of total testosterone and SHBG level.Studies have found an inverse correlation between the increase of kummerbund, the accumulation of visceral fat and total testosterone.Apply CT to analyze, the accumulation visceral fat and subcutaneous adipose tend to increase compared with the men gonad hypofunction and men with normal sex gland function of the same age.The clinical observation of male revealed a low testosterone and SHBG associated with abdominal obesity.

    5.Adrenal glands

    Adrenal gland is one of the important endocrine organs in the body, it secretes adrenalin, mineralocorticoid, glucocorticoid and nitrogenous hormones.Among these hormones, adrenalin and glucocorticoid have a very close relation to obesity.Energy and fat balance is regulated by adrenalin through the β3 receptor.Recent studies have

    shown that the expression of β3 receptor gen at obesity sensitive group of rats of

    brown fat tissue has decreased, while at obesity resistance group the expression of β3

    receptor gen has increased.Reveal that the β3 receptor paly a role in resist obesity at

    brown fat tissue.In short, adrenalin palys a very important role in the development of obesity, at the same time obesity is also associated with abnormal hormone levels of adrenal gland secretion.

    6.Gastrointestinal hormones

    The gastrointestinal tract can secrete a variety of hormones, these hormones has important influence to energy intake and energy metabolism.These hormones include:ghrelin, PYY, GLP-1, obestatin, PP, CCK, OXM and GIP.Ghrelin is the only known circulating orexigenic factor, has been found to be decreased in obese people, while increased in anorexia and cachexia patients.PYY1-36 and PYY3-36 are main form of PYY.PYY3-36 is the immune active site of PYY, play a role when combine with Y2 receptor.PYY3-36 reduce the eating of rodents and primates, then increase the accumulation of fat.GLP-1 is synthesized and secreted by gastrointestinal L-cell.GLP-1 can increase the level of insulin, increasing the number of β-cell and

    reducing the apoptosis of β-cell.GLP-1 reduce the eating of various of species,

    leading to weight loss.

    7.Thyroid gland

    In obesity there is also a trend to increased TSH and free T3 levels.The TSH

生命科学学院 2011 生命科学与技术基地班 胡升 1142043040

    level has increased in obese people.There is a positive correlation between TSH level and obesity, but an an inverse correlation between FT4 level and obesity.In obese people the FT3 level has increased.The study found that the low level of FT4 has a close relation to insulin resistance.Obesity condition of neuroendocrine function disorder could be the main cause of thyroid function change.

    Summary:

    The dysfunction of endocrine function can cause obesity.While obesity can cause the abnormal endocrine hormone metabolism,then leading to the abnormal distribution and function of adipose.The causal relationship between the dysfunction of endocrine function and obesity.And the dynamic change mechanism of hormones.These are some phenomena to be worthing further research.

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