Question

This is BIOchemistry) For the appetite-related signaling molecule GHRELIN:

a.) What is the specific function of that molecule?

b.) What is the mechanism of that action (how does it do what it does)?

c.) How is that molecule made? Describe any prepro- and pro- forms and associated cleavages or covalent bonds or phosphorylations associated with the molecule.

d.) Describe how the molecule is regulated

(This problem relates to chapters 22, Biosynthesis of amino acids, nucleotides, and related molecules; and chapter 23, hormonal regulation and integration of mammalian metabolism, from the Lehninger Biochemistry textbook).

Answer 1

SPECIFIC FUNCTION OF GHRELIN :-

• It is termed the ‘hunger hormone’ because it stimulates appetite, increases food intake and promotes fat storage.
• it circulates in the bloodstream and acts at the hypothalamus, an area of the brain crucial in the control of appetite.
• act on regions of the brain involved in reward processing such as the amygdala.
• stimulates the release of growth hormone from the pituitary gland, which, unlike ghrelin itself, breaks down fat tissue and causes the build-up of muscle.
• Ghrelin also has protective effects on the cardiovascular system and plays a role in the control of insulin release.

MECHANISM OF ACTION OF GHRELIN AND HOW GHRELIN ARE MADE GIVEN BELOW in attachement:-D) REGULATION OF GHRELIN :-

Ghrelin achieves these functions through binding the ghrelin receptor GHS-R in appetite-regulating neurons and in peripheral metabolic organs including the endocrine pancreas. Ghrelin levels are negatively correlated with body mass index (BMI) and insulin resistance. In addition, ghrelin secretion is impaired in obesity and insulin resistance.

The role of insulin and insulin resistance in the regulation of ghrelin secretion and on the role of ghrelin in glucose-stimulated insulin secretion (GSIS).

Ghrelin also plays an important role in regulating reward perception in dopamine neurons that link the ventral tegmental area to the nucleus accumbens (a site that plays a role in processing sexual desire, reward, and reinforcement, and in developing addictions) through its colocalized receptors and interaction with dopamine and acetylcholine.