What is the Testicular Target For Follicle Stimulating Hormone (FSH)?

Written by Ben Bunting: BA, PGCert. (Sport & Exercise Nutrition) // British Army Physical Training Instructor // S&C Coach.


The testicular target of follicle-stimulating hormone (FSH) is unclear. However, several areas of research are relevant.

These include Sertoli cells, Bok mRNA levels, and FSH receptor expression.

Follicle Stimulating Hormone Role in Males

Follicle Stimulating Hormon (FSH) is a key player in the male reproductive system. It is necessary for the production of sperm, but its lack can cause incomplete puberty and even infertility.

Men with low levels of FSH can be affected by a variety of conditions, such as primary ovarian insufficiency and hypergonadotrophic hypogonadism.

FSH is produced by the testes. It interacts with the granulosa cells in the ovaries. It also triggers ovulation, which results in the release of an egg from the follicle. FSH also plays an important role in maturation.

Follicle Stimulating Hormonal levels are closely linked to a woman's ovulation. In women, FSH stimulates the ovaries to produce eggs, while in males, it stimulates the sperm to mature. Its levels in the testicles are controlled by the hypothalamic-pituitary-gonadal axis.

A circulating hormone, GnRH, stimulates the production of FSH and luteinizing hormone in the anterior pituitary gland. These hormones then travel to the testes through blood vessels and bind to receptors on the testes.

The hormones are responsible for regulating growth and pubertal maturation, as well as reproduction.

In males, Follicle Stimulating Hormonal (FSH) and testosterone play a key role in the male reproductive system.

During childhood, FSH levels are low and the steroid output of the testes is minimal.

However, at the time of puberty, the Sertoli cells increase in number. It is believed that FSH stimulates Sertoli cell proliferation, which is crucial for the production of sperm.

The hormone also stimulates the production of androgen-binding protein by Sertoli cells, which is essential for normal spermatogenesis.

Sertoli cells

The secretion of follicle-stimulating hormone is directed at a specific target within the testis: the Sertoli cells.

These cells are support cells that extend from the basement membrane into the testicular lumen and are interspersed among germ cells.

They are nondividing and play a key role during spermatogenesis, nourishing developing sperm cells and acting as phagocytes.

During spermatogenesis, Sertoli cells also translocate cells from the base of the seminiferous tubule to the lumen of the tubule.

This process requires conformational changes in the lateral margins of the Sertoli cells.

The gene cx43 regulates Sertoli cell activity. Sertoli cells produce lactate, which is a source of energy for germ cells in relative hypoxic conditions. It also has antioxidant properties, helping to decrease reactive oxygen species in the testis.

Cyclin D1

Follicle-stimulating hormone (FSH) is a glycoprotein hormone that plays an essential role in mammalian reproduction. It binds to Sertoli cells and induces signaling in the cell.

When the hormone stimulates the cells, these cells respond to the hormone by regulating their own genes and producing regulatory signals. In the testis, this signaling leads to follicle maturation and ovulation.

FSH acts on Cyclin D1 at two levels - at the transcriptional level and the post-transcriptional level. It suppresses IRF-1 by affecting cyclin D1 expression.

The effects of FSH on Cyclin D1 are important for understanding the role of the hormone in testicular development.

Bok mRNA level

Using Northern hybridization, researchers evaluated changes in Bok mRNA levels in cultured seminiferous tubules.

They found that Bok is a potential target of FSH, as it regulates apoptosis and helps regulate the number of spermatogonial cells in the testis. Alcohol is a reproductive toxin and has been shown to reduce sperm production.

The follicle stimulating hormone targets the Bok gene, which is highly expressed in testis cells.

The hormone controls the activity of CREM through the Adenylate cyclase/cAMP/protein kinase A pathway. These two proteins activate G-protein-alpha-s-coupled receptors.

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FSHR receptor expression

Human follicle-stimulating hormone (FSH) and FSHR are two hormones that regulate the proliferation of Sertoli cells in the testis.

They are also critical in determining the size and spermatogenic potential of the testis. The FSH-regulated Sertoli cell proliferation depends on the FSHR receptor gene expression in the testicular follicles.

FSHR has two isoforms, FSHR1 and FSHR2. The FSHR1 isoform contains all ten exons and has a large N-terminal extracellular domain.

The FSHR1 protein has seven a-helical transmembrane domains and alternate intracellular loops. The FSHR2 variant has a truncated exon 10 and only a short intracellular domain.

Effects of fsh on spermatogenesis

The follicle-stimulating hormone or FSH plays a role in human fertility and spermatogenesis.

The hormone acts by stimulating follicles to divide and to produce sperm. It acts on the follicles' receptors on the basolateral membranes, which are responsible for regulating the hormone's activity.

The hormone also stimulates the production of androgen-binding proteins in the Sertoli cells, which is crucial for spermatogenesis.

The effects of FSH on spermatogenesis have not been clearly established. However, a number of animal models have revealed some positive results.

FSH is an essential hormone in the process of spermatogenesis and is responsible for stimulating cell proliferation in the seminiferous epithelium.

In normal men, the hormone is also required for the maturation and differentiation of spermatogonial cells.

FSHR-D567G vs FSHR-N431I mutations

Mutations of the testicular target for follicle stimulating hormonal (FSH) gene can cause infertility. The hormone is involved in regulating the cell cycle, gene expression and DNA replication.

FSH also elevates the expression of Sertoli cell genes, which proliferate extensively in neonatal life. These cells are enriched in genes involved in stem cell differentiation and the cell cycle.

One of these genes is Kruppel-like factor 4, which plays a key role in the timing and differentiation of Sertoli cells.

In vitro studies, the D567G mutation increased basal cAMP production by 1.5-fold.

However, the FSHR-N431I mutation resulted in decreased agonist-stimulated receptor desensitization and impaired receptor internalization, resulting in pseudo-constitutive FSH signaling.

These effects may explain the discrepancy between the two male phenotypes caused by FSHR mutations.

What is the Testicular Target For Follicle Stimulating Hormone Conclusion?

Follicle stimulating hormone (FSH) is an important hormone that regulates the development of the testes.

It acts on the Sertoli cells and stimulates them to proliferate. Its level is low during childhood, but it is increased during puberty.

It appears to regulate the proliferation of the cells, and intratesticular testosterone may be required for its action.

A complete lack of follicle stimulating hormone leads to incomplete puberty and infertility because the ovaries are unable to produce enough sperm.

Partially deficient levels of follicle stimulating hormone may lead to delayed puberty or limited sperm production, but fathering a child is still possible.

FSH is produced by the pituitary gland and released into the bloodstream by the ovaries. It is carried in the bloodstream and binds to receptors in the testes.

It promotes the development of sperm and increases the production of oestradiol. However, in some patients, excess follicle stimulating hormone may be harmful.

Follicle-stimulating hormone also regulates the growth of bone. It works in concert with gonadal steroids to regulate bone development.

This hormone also influences sperm motility. These are just a few of the important roles of follicle-stimulating hormone. 

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