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Ghrelin Research Paper

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The peptide hormone ghrelin is secreted by the gastrointestinal tract, and plays a pivotal role in appetite stimulation through its action on hypothalamic neurons. Ghrelin is bound by the presynaptic terminals of neurons that secrete neuropeptide Y (NPY). These cells also receive afferent signals from neurons in the area of the brain adjacent to the third ventricle, but between the ARN and PVN groups.

Ghrelin increases the activity of the arcuate neurons which secrete NPY and have NPY-like actions on the paraventricular nucleus. It is postulated that ghrelin causes the release of orexigenic molecules that increase appetite at these sites, regulating in turn energy production and its conservation in the body.

Ghrelin in the brain
Ghrelin …show more content…
This action occurs when it binds to the GHS-R located in many sites in the central nervous system. These include the hypothalamic nuclei, the hippocampus, the amygdala, the caudal part of the brain stem, and the dopaminergic neurons in the midbrain.

Ghrelin in the rest of the body
Ghrelin also acts on insulin secretion, inhibiting it and thus reducing the level of gluconeogenesis and glycogenolysis. This effect is produced by heteromerization between the ghrelin receptor, GHS-R, and the somatostatin receptor, because different subunits are activated depending on whether ghrelin or somatostatin levels are higher. Ghrelin also acts via dopaminergic neurons in the ventral tegmental area (VTA) to produce its glycemic effect, as well as through GHS-R in the hindbrain.

Apart from its effect on increased adipogenesis and decreased lipolysis, ghrelin also acts to reduce heat production, notably by non-shivering thermogenesis in brown fat. Moreover, it reduces sympathetic nervous impulse production and transmission. A raised ghrelin concentration is therefore a favorable marker in myocardial infarction as it indicates a lower sympathetic

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