Nori Sheep Inhibin A ELISA Kit Summary

Alternative names for Inhibin A: INHA, inhibin alpha chain

Alternative names for sheep: Ovine, lamb, goat, caprine

P38440

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: 

Inhibin A is alpha subunit of inhibin and has almost directly opposite biological effects compared to activin and downregulates FSH synthesis and inhibits FSH secretion. Inhibin is a dimer wherein the first component is a beta subunit similar or identical to the beta subunit in activin, but  the second component of the inhibin dimer is a more distantly-related alpha subunit.^[1][2]  Inhibin belongs to the TGF-β protein superfamily.^[3] Inhibin does not inhibit the secretion of GnRH from the hypothalamus.^[4] However, the overall mechanism differs between the sexes. In females, inhibin is produced in the gonads, pituitary gland, placenta, corpus luteum and other organs. FSH stimulates the secretion of inhibin from the granulosa cells of the ovarian follicles in the ovaries. In turn, inhibin suppresses FSH. Inhibin A reaches its peak in the mid-luteal phase. Inhibin secretion is diminished by GnRH, and enhanced by insulin-like growth factor-1 (IGF-1). In males, inhibin is secreted from the Sertoli cells,^[5] located in the seminiferous tubules inside the testes. In contrast to activin, much less is known about the mechanism of action of inhibin, but may involve competing with activin for binding to activin receptors and/or binding to inhibin-specific receptors.^[2] Quantification of inhibin A is part of the prenatal quad screen that can be administered during pregnancy at a gestational age of 16–18 weeks. An elevated inhibin A (along with an increased beta-hCG, decreased AFP, and a decreased estriol) is suggestive of the presence of a fetus with Down syndrome.^[6] As a screening test, abnormal quad screen test results need to be followed up with more definitive tests.

References

1. Burger HG, Igarashi M (1988). J Clinical Endocrinol Metabolism. 66 (4): 885–6.
2. Robertson DM, et al. (2004). Endocrine-Related Cancer. 11 (1): 35–49.
3. Kingsley DM (1994). Genes & Development. 8 (2): 133–46.
4. Luisi S, et al. (2005). Human Reproduction Update. 11 (2): 123–35.
5. Skinner MK, et al. (1989). Molecular and Cellular Endocrinology. 66 (2): 239–49.
6. Aitken DA, et al. (1996). The New England Journal of Medicine. 334 (19): 1231–6.