Adipose derived hormones
Encyclopedia
Adipose tissue
is an important endocrine organ that secretes numerous protein hormones, including leptin
, adiponectin
, and resistin
. These hormones generally influence energy metabolism, which is of great interest to the understanding and treatment of type 2 diabetes and obesity
.
Their relative roles in modifying appetite
, insulin resistance
and atherosclerosis
are the subjects of intense research, as they may be modifiable causes of morbidity in people with obesity
.
. However, the importance of adipose tissue as an endocrine organ was only fully appreciated in 1995 with the discovery of Leptin
, the protein product of the Ob gene. Leptin is a strong appetite suppressant that, when deleted, causes early onset severe obesity in humans and in animal models. The discovery of leptin
and its effects on appetite led to hopes of a treatment for obesity
and type 2 diabetes, a major disease in the developed world. Unfortunately, clinical studies using leptin as a treatment for obesity in humans failed to show improvement, leading some scientists to conclude that the brain can become resistant to leptin, even at supra-physiological levels (the so-called "ceiling effect"), rendering treatment with leptin ineffective. However, as geneticists learn more from the few cases of leptin gene mutations, the possibility remains that, although leptin was ineffective at treating obesity across the population, some individual obese patients might still benefit from its use as an anti-obesity medication.
Research into the adipose-derived hormones adiponectin and resistin is ongoing. Like leptin, these hormones also affect energy balance and metabolism, and are therefore targets for new drug research.
Adipose tissue
In histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
is an important endocrine organ that secretes numerous protein hormones, including leptin
Leptin
Leptin is a 16 kDa protein hormone that plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. It is one of the most important adipose derived hormones...
, adiponectin
Adiponectin
Adiponectin is a protein which in humans is encoded by the ADIPOQ gene.- Structure :...
, and resistin
Resistin
Resistin also known as adipose tissue-specific secretory factor or C/EBP-epsilon-regulated myeloid-specific secreted cysteine-rich protein is a cysteine-rich protein that in humans is encoded by the RETN gene....
. These hormones generally influence energy metabolism, which is of great interest to the understanding and treatment of type 2 diabetes and obesity
Obesity
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...
.
Their relative roles in modifying appetite
Appetite
The appetite is the desire to eat food, felt as hunger. Appetite exists in all higher life-forms, and serves to regulate adequate energy intake to maintain metabolic needs. It is regulated by a close interplay between the digestive tract, adipose tissue and the brain. Decreased desire to eat is...
, insulin resistance
Insulin resistance
Insulin resistance is a physiological condition where the natural hormone insulin becomes less effective at lowering blood sugars. The resulting increase in blood glucose may raise levels outside the normal range and cause adverse health effects, depending on dietary conditions. Certain cell types...
and atherosclerosis
Atherosclerosis
Atherosclerosis is a condition in which an artery wall thickens as a result of the accumulation of fatty materials such as cholesterol...
are the subjects of intense research, as they may be modifiable causes of morbidity in people with obesity
Obesity
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...
.
History of adipose derived hormones
It had been shown that adipose tissue secreted some unknown factor that influenced appetiteAppetite
The appetite is the desire to eat food, felt as hunger. Appetite exists in all higher life-forms, and serves to regulate adequate energy intake to maintain metabolic needs. It is regulated by a close interplay between the digestive tract, adipose tissue and the brain. Decreased desire to eat is...
. However, the importance of adipose tissue as an endocrine organ was only fully appreciated in 1995 with the discovery of Leptin
Leptin
Leptin is a 16 kDa protein hormone that plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. It is one of the most important adipose derived hormones...
, the protein product of the Ob gene. Leptin is a strong appetite suppressant that, when deleted, causes early onset severe obesity in humans and in animal models. The discovery of leptin
Leptin
Leptin is a 16 kDa protein hormone that plays a key role in regulating energy intake and energy expenditure, including appetite and metabolism. It is one of the most important adipose derived hormones...
and its effects on appetite led to hopes of a treatment for obesity
Obesity
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have an adverse effect on health, leading to reduced life expectancy and/or increased health problems...
and type 2 diabetes, a major disease in the developed world. Unfortunately, clinical studies using leptin as a treatment for obesity in humans failed to show improvement, leading some scientists to conclude that the brain can become resistant to leptin, even at supra-physiological levels (the so-called "ceiling effect"), rendering treatment with leptin ineffective. However, as geneticists learn more from the few cases of leptin gene mutations, the possibility remains that, although leptin was ineffective at treating obesity across the population, some individual obese patients might still benefit from its use as an anti-obesity medication.
Research into the adipose-derived hormones adiponectin and resistin is ongoing. Like leptin, these hormones also affect energy balance and metabolism, and are therefore targets for new drug research.