Description

Nori Turkey Ghrelin ELISA Kit Summary

Alternative names for ghrelin: GHRL

Standard Curve

Kit Components
1. Pre-coated 96-well Microplate
2. Biotinylated Detection Antibody
3. Streptavidin-HRP Conjugate
4. Lyophilized Standards
5. TMB One-Step Substrate
6. Stop Solution
7. 20 x PBS
8. Assay Buffer

Other Materials Required but not Provided:
1. Microplate Reader capable of measuring absorption at 450 nm
2. Log-log graph paper or computer and software for ELISA data analysis
3. Precision pipettes (1-1000 µl)
4. Multi-channel pipettes (300 µl)
5. Distilled or deionized water

Protocol Outline
1. Prepare all reagents, samples and standards as instructed in the datasheet.
2. Add 100 µl of Standard or samples to each well and incubate 1 h at RT.
3. Add 100 µl of Working Detection Antibody to each well and incubate 1 h at RT.
4. Add 100 µl of Working Streptavidin-HRP to each well and incubate 20 min at RT.
5. Add 100 µl of Substrate to each well and incubate 5-30 min at RT.
6. Add 50 µl of Stop Solution to each well and read at 450 nm immediately.

Background: 

Ghrelin, a hunger hormone, also known as lenomorelin, is a peptide hormone produced by ghrelinergic cells in the gastrointestinal tract.^[1] Ghrelin functions as a neuropeptide in the central nervous system^[2] and regulates appetite and energy homeostasis.^[3] Ghrelin is encoded by the GHRL gene and is presumably produced from the cleavage of the prepropeptide ghrelin/obestatin. Full-length preproghrelin is homologous to promotilin and both are members of the motilin family. When the stomach is empty, ghrelin is secreted. When the stomach is stretched, secretion stops. It acts on hypothalamic brain cells both to increase hunger, and to increase gastric acid secretion and gastrointestinal motility to prepare the body for food intake.^[4] Ghrelin was found to be upregulated by stress even in the absence of adrenal hormones.^[5] The receptor for ghrelin, the ghrelin/growth hormone secretagogue receptor, is found on the same cells in the brain as the receptor for leptin, the satiety hormone that has opposite effects from ghrelin.^[5] Ghrelin also regulates reward cognition in dopamine neurons that link the ventral tegmental area to the nucleus accumbens^[6] through its colocalized receptors and interaction with dopamine and acetylcholine.^[2] Unlike the case of many other endogenous peptides, ghrelin can cross the blood-brain-barrier, giving exogenously-administered ghrelin unique clinical potential. In addition to its function in energy homeostasis, ghrelin also activates the cholinergic–dopaminergic reward link in inputs to the ventral tegmental area and in the mesolimbic pathway,^[6] a circuit that communicates the hedonic and reinforcing aspects of natural rewards,^[2] such as food and addictive drugs such as ethanol. Ghrelin receptors are located on neurons in this circuit.^[2] Hypothalamic ghrelin signalling is required for reward from alcohol and palatable/rewarding foods. Ghrelin has been linked to inducing appetite and feeding behaviors. Circulating ghrelin levels are the highest right before a meal and the lowest right after.^[7] Injections of ghrelin in both humans and rats have been shown to increase food intake in a dose-dependent manner.^[8] However, ghrelin does not increase meal size, only meal number. Studies have shown that ghrelin levels are negatively correlated with weight. This data suggests that ghrelin functions as an adiposity signal, a messenger between the body’s energy stores and the brain.^[4]

References

1. Inui A, et al. (2004). The FASEB Journal. 18 (3): 439–56.
2. Dickson SL, et al. (2011). Molecular and Cellular Endocrinology. 340 (1): 80–87.
3. Burger KS, Berner LA (2014). Physiology & Behavior. 136: 121–27.
4. Schwartz MW, et al. (2000). Nature. 404 (6778): 661–71.
5. Perello M, et al. (2012). The Journal of Comparative Neurology. 520 (2): 281–94.
6. Naleid AM, et al. (2005). Peptides. 26 (11): 2274–79.
7. Tolle V, et al. (2002). Endocrinology. 143 (4): 1353–61.
8. Wren AM, et al. (2000). Endocrinology. 141 (11): 4325–28.

Product Citation