Description

Nori Rat Leptin ELISA Kit Summary

Alternative names for leptin: satiety hormone, ob gene

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: 

Leptin, the “satiety hormone,” is a hormone made by adipose cells that helps to regulate energy balance by inhibiting hunger. Leptin is opposed by the actions of the hormone ghrelin, the “hunger hormone”. Both hormones act on receptors in the arcuate nucleus of the hypothalamus to regulate appetite to achieve energy homeostasis.^[1] In obesity, a decreased sensitivity to leptin occurs, resulting in an inability to detect satiety despite high energy stores.^[2] Leptin is produced primarily in the adipocytes of white adipose tissue but also produced by brown adipose tissue, placenta, ovaries, skeletal muscle, stomach, mammary epithelial cells, bone marrow,^[4]gastric chief cells and P/D1 cells.^[1] Leptin circulates in blood in free form and bound to proteins. Leptin acts on receptors in the lateral hypothalamus to inhibit hunger and the medial hypothalamus to stimulate satiety.^[4] The absence of leptin (or its receptor) leads to uncontrolled hunger and resulting obesity. Leptin binds to neuropeptide Y (NPY) neurons in the arcuate nucleus to decrease the activity of these neurons. Leptin receptor activation inhibits NPY and agouti-related peptide, and activates α-melanocyte-stimulating hormone (α-MSH). Leptin interacts with six types of receptors, which in turn are encoded by a single gene, LEPR.^[5] Ob-Rb is the only receptor isoform that can signal intracellularly via the Jak-Stat and MAPK signal transduction pathways,^[6] and is present in hypothalamic nuclei. Once leptin has bound to the Ob-Rb receptor, it activates the stat3.^[7] Leptin has additional functions and is a pro-angiogenic, pro-inflammatory and mitogenic factor, the actions of which are reinforced through crosstalk with IL-1 family cytokines in cancer.^[8] Leptin resembles IL-6 and is a member of the cytokine superfamily.  Leptin’s role as an inflammatory marker is to respond specifically to adipose-derived inflammatory cytokines. ^[9] Similar to what is observed in chronic inflammation, chronically elevated leptin levels are associated with obesity, overeating, and inflammation-related diseases, including hypertension, metabolic syndrome, and cardiovascular disease.

References

1. Brennan AM, Mantzoros CS (2006). Nat Clin Pract Endocrinol Metab 2 (6): 318–27.
2. Pan H, Guo J, Su Z (2014). Physiology & Behavior 130: 157–169.
3. Margetic S, et al. (2002). Int. J. Obes. Relat. Metab. Disord. 26 (11): 1407–1433.
4. Elmquist JK, Elias CF, Saper CB (Feb 1999). Neuron 22 (2): 221–32.
5. Wang MY, Zhou YT, Newgard CB, Unger RH (1996). FEBS Lett. 392 (2): 87–90.
6. Malendowicz W, et al. (2006). Int. J. Mol. Med. 18 (4): 615–8.
7. Di Marzo V (2008). Diabetologia 51 (8): 1356–67.
8. Perrier S, et al. (2009). FEBS Lett. 583 (2): 259–65.
9. Hamilton BS, et al. (1995). Nat. Med. 1 (9): 953–956.

Product Citation