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Inhibin, beta B, also known as INHBB, is a protein which in humans is encoded by the INHBB gene.[1][2] INHBB is a subunit of both activin and inhibin, two closely related glycoproteins with opposing biological effects.



Inhibins are heterodimeric glycoproteins composed of an α subunit (INHA) and one of two homologous, but distinct, β subunits (βA or βB, this protein). mRNA for the two subunits has been demonstrated in the testes of adult rats.[3] Inhibin can bind specifically to testicular interstitial cells throughout development and may be an important regulator of Leydig cell testosterone production or interstitial cell function.[4]

The inhibin beta B subunit joins the α subunit to form a pituitary FSH secretion inhibitor. Inhibin has been shown to regulate gonadal stromal cell proliferation negatively and to have tumour-suppressor activity. In addition, serum levels of inhibin have been shown to reflect the size of granulosa-cell tumors and can therefore be used as a marker for primary as well as recurrent disease. Because expression in gonadal and various extragonadal tissues may vary severalfold in a tissue-specific fashion, it is proposed that inhibin may be both a growth/differentiation factor and a hormone.


Furthermore, the beta B subunit forms a homodimer, activin B, and also joins with the beta A subunit to form a heterodimer, activin AB, both of which stimulate FSH secretion.[2]

Tissue distribution

Sections of testicular tissue from rat revealed positive immunoreactivity against anti-inhibin intensely appeared in Leydig cells.[5] In adult animals, binding of 125I inhibin was localized primarily to the interstitial compartment of the testis.[4] Also, Jin et al., (2001) reported that Leydig cells showed strong positive staining for the inhibin βA subunit in pigs testis.[6]


In situ ligand binding studies have shown that 125I inhibin βA binds specifically to Leydig cells throughout rat testis development. These results suggest that inhibin has been considered as a regulator of Leydig cell differentiated function.[7][8] Recently, additional inhibin specific binding proteins were identified in inhibin target tissues, including pituitary and Leydig cells.[9][10] From these receptors β-glycan (the TGFß type III receptor) and InhBP/p120 (a membrane-tethered proteoglycan) were identified as putative inhibin receptors and they are all present in Leydig cells. However, a faint positive reaction was detected in Leydig cell cytoplasm in rats treated with anise oil.[5] This may be related to the damaged Leydig cells, as a result of the decreasing of inhibin expression. This may be related to its content of safrole.


  1. Burger HG, Igarashi M (April 1988). "Inhibin: definition and nomenclature, including related substances". Endocrinology. 122 (4): 1701–2. doi:10.1210/endo-122-4-1701. PMID 3345731.
  2. 2.0 2.1 "Entrez Gene: INHBB inhibin, beta B (activin AB beta polypeptide)".
  3. Feng ZM, Bardin CW, Chen CL (June 1989). "Characterization and regulation of testicular inhibin beta-subunit mRNA". Mol. Endocrinol. 3 (6): 939–48. doi:10.1210/mend-3-6-939. PMID 2739657.
  4. 4.0 4.1 Krummen LA, Moore A, Woodruff TK, Covello R, Taylor R, Working P, Mather JP (April 1994). "Localization of inhibin and activin binding sites in the testis during development by in situ ligand binding". Biol. Reprod. 50 (4): 734–44. doi:10.1095/biolreprod50.4.734. PMID 8199254.
  5. 5.0 5.1 Ibrahim, A.A.E.M (2008). "Correlation between fennel-or anise-oil administration and damage to the testis of adult rats". Egyptian Journal of Biology. 10: 62–76.
  6. Jin W, Arai KY, Herath CB, Kondo M, Ishi H, Tanioka Y, Watanabe G, Groome NP, Taya K (2001). "Inhibins in the male Göttingen miniature pig: Leydig cells are the predominant source of inhibin B". J. Androl. 22 (6): 953–60. PMID 11700859.
  7. Lejeune H, Chuzel F, Sanchez P, Durand P, Mather JP, Saez JM (November 1997). "Stimulating effect of both human recombinant inhibin A and activin A on immature porcine Leydig cell functions in vitro". Endocrinology. 138 (11): 4783–91. doi:10.1210/en.138.11.4783. PMID 9348206.
  8. Pierson TM, Wang Y, DeMayo FJ, Matzuk MM, Tsai SY, Omalley BW (July 2000). "Regulable expression of inhibin A in wild-type and inhibin alpha null mice". Mol. Endocrinol. 14 (7): 1075–85. doi:10.1210/me.14.7.1075. PMID 10894156.
  9. Chong H, Pangas SA, Bernard DJ, Wang E, Gitch J, Chen W, Draper LB, Cox ET, Woodruff TK (July 2000). "Structure and expression of a membrane component of the inhibin receptor system". Endocrinology. 141 (7): 2600–7. doi:10.1210/en.141.7.2600. PMID 10875264.
  10. Bernard DJ, Chapman SC, Woodruff TK (February 2002). "Inhibin binding protein (InhBP/p120), betaglycan, and the continuing search for the inhibin receptor". Mol. Endocrinol. 16 (2): 207–12. doi:10.1210/me.16.2.207. PMID 11818494.

Further reading

  • Ying SY (1988). "Inhibins and activins: chemical properties and biological activity". Proc. Soc. Exp. Biol. Med. 186 (3): 253–64. doi:10.3181/00379727-186-42611a. PMID 3122219.
  • Munz B, Hübner G, Tretter Y, et al. (1999). "A novel role of activin in inflammation and repair". J. Endocrinol. 161 (2): 187–93. doi:10.1677/joe.0.1610187. PMID 10320815.
  • Welt CK (2002). "The physiology and pathophysiology of inhibin, activin and follistatin in female reproduction". Curr. Opin. Obstet. Gynecol. 14 (3): 317–23. doi:10.1097/00001703-200206000-00012. PMID 12032389.
  • Shav-Tal Y, Zipori D (2003). "The role of activin a in regulation of hemopoiesis". Stem Cells. 20 (6): 493–500. doi:10.1634/stemcells.20-6-493. PMID 12456957.
  • Lahlou N, Roger M (2005). "Inhibin B in pubertal development and pubertal disorders". Semin. Reprod. Med. 22 (3): 165–75. doi:10.1055/s-2004-831892. PMID 15319819.
  • Mathews LS, Vale WW (1991). "Expression cloning of an activin receptor, a predicted transmembrane serine kinase". Cell. 65 (6): 973–82. doi:10.1016/0092-8674(91)90549-E. PMID 1646080.
  • Schmelzer CH, Burton LE, Tamony CM, et al. (1990). "Purification and characterization of recombinant human activin B.". Biochim. Biophys. Acta. 1039 (2): 135–41. doi:10.1016/0167-4838(90)90178-I. PMID 2364091.
  • Mason AJ, Berkemeier LM, Schmelzer CH, Schwall RH (1990). "Activin B: precursor sequences, genomic structure and in vitro activities". Mol. Endocrinol. 3 (9): 1352–8. doi:10.1210/mend-3-9-1352. PMID 2575216.
  • Feng ZM, Bardin CW, Chen CL (1989). "Characterization and regulation of testicular inhibin beta-subunit mRNA". Mol. Endocrinol. 3 (6): 939–48. doi:10.1210/mend-3-6-939. PMID 2739657.
  • Barton DE, Yang-Feng TL, Mason AJ, et al. (1989). "Mapping of genes for inhibin subunits alpha, beta A, and beta B on human and mouse chromosomes and studies of jsd mice". Genomics. 5 (1): 91–9. doi:10.1016/0888-7543(89)90091-8. PMID 2767687.
  • Burger HG, Igarashi M (1988). "Inhibin: definition and nomenclature, including related substances". Endocrinology. 122 (4): 1701–2. doi:10.1210/endo-122-4-1701. PMID 3345731.
  • Mason AJ, Niall HD, Seeburg PH (1986). "Structure of two human ovarian inhibins". Biochem. Biophys. Res. Commun. 135 (3): 957–64. doi:10.1016/0006-291X(86)91021-1. PMID 3754442.
  • Martens JW, de Winter JP, Timmerman MA, et al. (1997). "Inhibin interferes with activin signaling at the level of the activin receptor complex in Chinese hamster ovary cells". Endocrinology. 138 (7): 2928–36. doi:10.1210/endo.138.7.5250. PMID 9202237.
  • Mellor SL, Cranfield M, Ries R, et al. (2001). "Localization of activin beta(A)-, beta(B)-, and beta(C)-subunits in humanprostate and evidence for formation of new activin heterodimers of beta(C)-subunit". J. Clin. Endocrinol. Metab. 85 (12): 4851–8. doi:10.1210/jc.85.12.4851. PMID 11134153.
  • Chapman SC, Woodruff TK (2001). "Modulation of activin signal transduction by inhibin B and inhibin-binding protein (INhBP)". Mol. Endocrinol. 15 (4): 668–79. doi:10.1210/me.15.4.668. PMID 11266516.
  • Salmenkivi K, Arola J, Voutilainen R, et al. (2001). "Inhibin/activin betaB-subunit expression in pheochromocytomas favors benign diagnosis". J. Clin. Endocrinol. Metab. 86 (5): 2231–5. doi:10.1210/jc.86.5.2231. PMID 11344232.
  • Bahathiq AO, Stewart RL, Wells M, et al. (2002). "Production of activins by the human endosalpinx". J. Clin. Endocrinol. Metab. 87 (11): 5283–9. doi:10.1210/jc.2001-011884. PMID 12414903.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.