Obesity - Pathophysiology


Flier summarizes the many possible pathophysiological mechanisms involved in the development and maintenance of obesity. This field of research had been almost unapproached until leptin was discovered in 1994. Since this discovery, many other hormonal mechanisms have been elucidated that participate in the regulation of appetite and food intake, storage patterns of adipose tissue, and development of insulin resistance. Since leptin's discovery, ghrelin, insulin, orexin, PYY 3-36, cholecystokinin, adiponectin, as well as many other mediators have been studied. The adipokines are mediators produced by adipose tissue; their action is thought to modify many obesity-related diseases.

Leptin and ghrelin are considered to be complementary in their influence on appetite, with ghrelin produced by the stomach modulating short-term appetitive control (i.e. to eat when the stomach is empty and to stop when the stomach is stretched). Leptin is produced by adipose tissue to signal fat storage reserves in the body, and mediates long-term appetitive controls (i.e. to eat more when fat storages are low and less when fat storages are high). Although administration of leptin may be effective in a small subset of obese individuals who are leptin deficient, most obese individuals are thought to be leptin resistant and have been found to have high levels of leptin. This resistance is thought to explain in part why administration of leptin has not been shown to be effective in suppressing appetite in most obese people.

While leptin and ghrelin are produced peripherally, they control appetite through their actions on the central nervous system. In particular, they and other appetite-related hormones act on the hypothalamus, a region of the brain central to the regulation of food intake and energy expenditure. There are several circuits within the hypothalamus that contribute to its role in integrating appetite, the melanocortin pathway being the most well understood. The circuit begins with an area of the hypothalamus, the arcuate nucleus, that has outputs to the lateral hypothalamus (LH) and ventromedial hypothalamus (VMH), the brain's feeding and satiety centers, respectively.

The arcuate nucleus contains two distinct groups of neurons. The first group coexpresses neuropeptide Y (NPY) and agouti-related peptide (AgRP) and has stimulatory inputs to the LH and inhibitory inputs to the VMH. The second group coexpresses pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) and has stimulatory inputs to the VMH and inhibitory inputs to the LH. Consequently, NPY/AgRP neurons stimulate feeding and inhibit satiety, while POMC/CART neurons stimulate satiety and inhibit feeding. Both groups of arcuate nucleus neurons are regulated in part by leptin. Leptin inhibits the NPY/AgRP group while stimulating the POMC/CART group. Thus a deficiency in leptin signaling, either via leptin deficiency or leptin resistance, leads to overfeeding and may account for some genetic and acquired forms of obesity.

Read more about this topic:  Obesity

Other articles related to "pathophysiology":

Atrax Morgue - Partial Discography
... Homicidal Texture (Cass) Slaughter Productions 1995 Pathophysiology (Cass) Old Europa Cafe 1995 Untitled (Cass) Slaughter Productions 1995 Autoerotic Death (Cass, Ltd) BloodLust! 1996 Cut My ... Slaughter Productions 2002 La Casa Dalle Finestre Che Ridono (CDr) Slaughter Productions 2002 Pathophysiology (CDr) Transf/Order 2002 Sweetly (CDr, Album) Spatter 2002 Death ...
Pathophysiology - Uses
... Pathophysiology is a required area of study for nearly all healthcare professional school programs (medical, dental, physician assistant, occupational therapy, physical therapy ...
University Of Ostrava - Faculties and Departments - Faculty of Medicine - Department of Physiology and Pathophysiology
... The Department of Physiology and Pathophysiology is divided into Institute of Physiology and Institute of Pathophysiology ... the Department of Physiology and Pathophysiology carries out scientific research and produces expert reports ...
Tension Headache - Cause
... (NO) mechanisms suggest that NO may play a key role in the pathophysiology of CTTH ... spinal nucleus, thalamus, and cerebral cortex) is believed to be involved in the pathophysiology of chronic tension-type headache ... a dysfunction in pain inhibitory systems may also play a role in the pathophysiology of chronic tension-type headache ...