Leydig Cell Aging and Hypogonadism

[Michael Scally MD]

Highlights
· Review changes in the steroidogenic enzymes of aging Leydig cells
· Discusses effects of the redox environment on Leydig cell testosterone production.
· Discusses ways to increase serum testosterone by stimulating the Leydig cells.

Beattie MC, Adekola L, Papadopoulos V, Chen H, Zirkin BR. Leydig Cell Aging and Hypogonadism. Exp Gerontol. https://www.sciencedirect.com/science/article/pii/S0531556515000765

Leydig cell testosterone (T) production is reduced with age, resulting in reduced serum T levels (hypogonadism). A number of cellular changes have been identified in the steroidogenic pathway of aged Leydig cells that are associated with reduced T formation, including reductions in luteinizing hormone (LH)-stimulated cAMP production, the cholesterol transport proteins steroidogenic acute regulatory (STAR) protein and translocator protein (TSPO), and downstream steroidogenic enzymes of the mitochondria and smooth endoplasmic reticulum.

Many of the changes in steroid formation that characterize aged Leydig cells can be elicited by the experimental alteration of the redox environment of young cells, suggesting that changes in the intracellular redox balance may cause reduced T production.

Hypogonadism is estimated to affect about 5 million American men, including both aged and young. This condition has been linked to mood changes, worsening cognition, fatigue, depression, decreased lean body mass, reduced bone mineral density, increased visceral fat, metabolic syndrome, decreased libido, and sexual dysfunction.

Exogenous T administration is now used widely to elevate serum T levels in hypogonadal men and thus to treat symptoms of hypogonadism. However, recent evidence suggests that men who take exogenous T may face increased risk of stroke, heart attack, and prostate tumorigenesis.

Moreover, it is well established that administered T can have suppressive effects on LH, resulting in lower Leydig cell T production, reduced intratesticular T concentration, and reduced spermatogenesis. This makes exogenous T administration inappropriate for men who wish to father children.

There are promising new approaches to increase serum T by directly stimulating Leydig cell T production rather than by exogenous T therapy, thus potentially avoiding some of its negative consequences.

 

[Mr.B66]

The article states that' there are promising new approaches to increase serum T' what would these promising new approaches be? Any studies or links available for reading?

 

[FockU]

The article states that' there are promising new approaches to increase serum T' what would these promising new approaches be? Any studies or links available for reading?

There are promising new approaches to increase serum T by directly stimulating Leydig cell T production rather than by exogenous T therapy, thus potentially avoiding some of its negative consequences.

Sounds like HCG bud

 

[Mr.B66]

Sounds like HCG bud

I see ! I thought maybe there was some NEW form of treating low T
Thanks bro!!!!

 

[Michael Scally MD]

Leydig Cells: Formation, Function and Regulation

Herein we summarize important discoveries made over many years about Leydig cell function and regulation. During the fetal period, fetal Leydig cells produce the high levels of androgen (testosterone or androstenedione, depending upon the species) required for differentiation of male genitalia and brain masculinization. Androgen production declines with loss of these cells, reaching a nadir at postpartum. Testosterone then gradually increases to high levels with adult Leydig cell development from stem cells.

In the adult, luteinizing hormone [LH] binding to Leydig cell LH receptors stimulates cAMP production, increasing the rate of cholesterol translocation into the mitochondria. Cholesterol is metabolized to pregnenolone by the CYP11A1 enzyme at the inner mitochondrial membrane, and pregnenolone to testosterone by mitochondria and smooth endoplasmic reticulum enzymes.

Cholesterol translocation to the inner mitochondrial membrane is mediated by a protein complex formed at mitochondrial contact sites that consists of the cholesterol binding translocator protein [TSPO], voltage dependent anion channel [VDAC], and other mitochondrial and cytosolic proteins.

Steroidogenic acute regulatory protein [STAR] acts at this complex to enhance cholesterol movement across the membranes and thus increase testosterone formation. The 14-3-3gamma and epsilon adaptor proteins serve as negative regulators of steroidogenesis, controlling the maximal amount of steroid formed. Decline in testosterone production occurs in many aging and young men, resulting in metabolic and quality-of-life changes.

Testosterone replacement therapy is widely used to elevate serum testosterone levels in hypogonadal men. With knowledge gained of the mechanisms involved in testosterone formation, it also is conceivable to use pharmacological means to increase serum testosterone by Leydig cell stimulation.

Zirkin BR, Papadopoulos V. Leydig Cells: Formation, Function and Regulation. Biology of reproduction 2018. Leydig Cells: Formation, Function and Regulation | Biology of Reproduction | Oxford Academic

 

[Michael Scally MD]

Chen F, Lu H, Chen P, et al. Acute Effects of the Translocator Protein (TSPO) Drug Ligand FGIN-1-27 on Serum Testosterone and LH Levels in Male Sprague Dawley Rats. Biology of reproduction 2018. Acute Effects of the Translocator Protein (TSPO) Drug Ligand FGIN-1-27 on Serum Testosterone and LH Levels in Male Sprague Dawley Rats | Biology of Reproduction | Oxford Academic

We reported that FGIN-1–27 (N, N-dihexyl-2-(4-fluorophenyl)indole-3-acetamide, FGIN), a synthetic ligand for translocator protein (TSPO, 18 kDa), increased serum testosterone levels in young and aged Brown Norway rats after its administration daily for 10 days.

It is not known, however, how soon after treatment with FGIN serum testosterone rises, how long levels remain elevated after cessation of treatment, or whether the drug acts solely through TSPO.

Adult Sprague Dawley male rats received a single ip dose of FGIN (1mg/kg BW). Serial blood samples were collected and serum testosterone and LH were assessed hourly throughout 24 hours.

Testosterone concentration was maximal by 3 hours, remained significantly higher than the controls at 10 hours, and returned to the control level by 24 hours. Consistent with the in vivo study, culturing isolated Leydig cells with either FGIN (40μM) or LH (0.1ng/ml) resulted in significantly increased testosterone production by 30 mins, and the stimulatory effects persisted through 48 hours. At a very early (15 min) treatment time, however, FGIN significantly increased testosterone production but LH had not yet done so.

Surprisingly, in vivo treatment with FGIN not only increased serum testosterone but also serum LH concentration, raising the possibility that FGIN may increase serum testosterone concentration by dual mechanisms.

 

[Michael Scally MD]

[Rats] Effects of Pharmacologically Induced Leydig Cell Testosterone Production on Intratesticular Testosterone and Spermatogenesis

The Leydig cells of the mammalian testis produce testosterone (T) in response to luteinizing hormone (LH). In rats and men with reduced serum T levels, T replacement therapy (TRT) will raise T levels, but typically with suppressive effects on sperm formation.

The rate-determining step in T formation is the translocation of cholesterol to the inner mitochondrial membrane, mediated by protein-protein interactions of cytosolic and outer mitochondrial membrane proteins. Among the involved proteins is cholesterol-binding translocator protein (18 kDa TSPO).

We hypothesized that in contrast to TRT, the administration of the TSPO agonist FGIN-1-27, by stimulating the ability of the Leydig cells to produce T, would result in the elevation of serum T levels while maintaining intratesticular T concentration and therefore without suppression of spermatogenesis.

Age-related reductions in both serum and intratesticular T levels were seen in old Brown Norway rats. Both exogenous T and FGIN-1-27 increased serum T levels. With exogenous T, serum LH and Leydig cell T formation were suppressed, and intratesticular T was reduced to below the concentration required to maintain spermatogenesis quantitatively.

In contrast, FGIN-1-27 stimulated Leydig cell T formation, resulting in increased serum T without reductions in intratesticular T concentrations or in testicular sperm numbers. FGIN-1-27 also significantly increased serum and intratesticular T levels in rats made LH-deficient by treatment with the GnRH antagonist cetrorelix.

These results point to a possible approach to increasing serum T without negative effects on spermatogenesis, based upon stimulating T production by the Leydig cells themselves rather than administering T exogenousl.

Chung J-Y, Brown S, Chen H, Liu J, Papadopoulos V, Zirkin B. Effects of Pharmacologically Induced Leydig Cell Testosterone Production on Intratesticular Testosterone and Spermatogenesis. Biology of Reproduction 2019. Effects of Pharmacologically Induced Leydig Cell Testosterone Production on Intratesticular Testosterone and Spermatogenesis

 

[Sworder]

They say that the human body rids itself of the cells every 10 years or something like that. Does that apply to fat and muscle cells as well(Leydig and Sertoli?) Wouldn't killing the cells rid the cells of multiple nuclei which is responsible to my understanding for so called muscle memory?

 

[Michael Scally MD]

Age-Related Changes in Human Leydig Cell Status

Study question: What are the consequences of ageing on human Leydig cell number and hormonal function?

Summary answer: Leydig cell number significantly decreases in parallel with INSL3 expression and Sertoli cell number in aged men, yet the in vitro Leydig cell androgenic potential does not appear to be compromised by advancing age.

What is known already: There is extensive evidence that ageing is accompanied by decline in serum testosterone levels, a general involution of testis morphology and reduced spermatogenic function. A few studies have previously addressed single features of the human aged testis phenotype one at a time, but mostly in tissue from patients with prostate cancer.

Study design, size, duration: This comprehensive study examined testis morphology, Leydig cell and Sertoli cell number, steroidogenic enzyme expression, INSL3 expression and androgen secretion by testicular fragments in vitro. The majority of these endpoints were concomitantly evaluated in the same individuals that all displayed complete spermatogenesis.

Participants/materials, setting, methods: Testis biopsies were obtained from 15 heart beating organ donors (age range: 19-85 years) and 24 patients (age range: 19-45 years) with complete spermatogenesis. Leydig cells and Sertoli cells were counted following identification by immunohistochemical staining of specific cell markers.

Gene expression analysis of INSL3 and steroidogenic enzymes was carried out by qRT-PCR. Secretion of 17-OH-progesterone, dehydroepiandrosterone, androstenedione and testosterone by in vitro cultured testis fragments was measured by LC-MS/MS. All endpoints were analysed in relation to age.

Main results and the role of chance: Increasing age was negatively associated with Leydig cell number (R = -0.49; P < 0.01) and concomitantly with the Sertoli cell population size (R= -0.55; P < 0.001). A positive correlation (R = 0.57; P < 0.001) between Sertoli cell and Leydig cell numbers was detected at all ages, indicating that somatic cell attrition is a relevant cellular manifestation of human testis status during ageing. INSL3 mRNA expression (R= -0.52; P < 0.05) changed in parallel with Leydig cell number and age.

Importantly, steroidogenic capacity of Leydig cells in cultured testis tissue fragments from young and old donors did not differ. Consistently, age did not influence the mRNA expression of steroidogenic enzymes. The described changes in Leydig cell phenotype with ageing are strengthened by the fact that the different age-related effects were mostly evaluated in tissue from the same men.

Limitations, reasons for caution: In vitro androgen production analysis could not be correlated with in vivo hormone values of the organ donors. In addition, the number of samples was relatively small and there was scarce information about the concomitant presence of potential confounding variables.

Wider implications of the findings: This study provides a novel insight into the effects of ageing on human Leydig cell status. The correlation between Leydig cell number and Sertoli cell number at any age implies a connection between these two cell types, which may be of particular relevance in understanding male reproductive disorders in the elderly.

However aged Leydig cells do not lose their in vitro ability to produce androgens. Our data have implications in the understanding of the physiological role and regulation of intratesticular sex steroid levels during the complex process of ageing in humans.

Mularoni V, Esposito V, Di Persio S, Vicini E, Spadetta G, Berloco P, Fanelli F, Mezzullo M, Pagotto U, Pelusi C, Nielsen JE, Rajpert-De Meyts E, Jorgensen N, Jorgensen A, Boitani C. Age-related changes in human Leydig cell status. Hum Reprod. 2020 Oct 23:deaa271. doi: 10.1093/humrep/deaa271. Epub ahead of print. PMID: 33094328. https://academic.oup.com/humrep/advance-article-abstract/doi/10.1093/humrep/deaa271/5936052?redirectedFrom=fulltext

 

[Michael Scally MD]

[OA] Dependence of Leydig Cell's Mitochondrial Physiology on Luteinizing Hormone Signaling

Knowledge about the relationship between steroidogenesis and the regulation of the mitochondrial bioenergetics and dynamics, in steroidogenic cells, is not completely elucidated. Here we employed in vivo and ex vivo experimental models to analyze mitochondrial physiology in Leydig cells depending on the different LH-cAMP environments.

Activation of LH-receptor in rat Leydig cells ex and in vivo triggered cAMP, increased oxygen consumption, mitoenergetic and steroidogenic activities. Increased mitoenergetic activity i.e., ATP production is achieved through augmented glycolytic ATP production and a small part of oxidative phosphorylation (OXPHOS).

Transcription of major genes responsible for mitochondrial dynamics was upregulated for Ppargc1a (regulator of mitogenesis and function) and downregulated for Drp1 (main fission marker), Prkn, Pink1 and Tfeb (mitophagy markers).

Leydig cells from gonadotropin-treated rats show increased mitogenesis confirmed by increased mitochondrial mass, increased mtDNA, more frequent mitochondria observed by a transmission electron microscope and increased expression of subunits of respiratory proteins Cytc/CYTC and COX4.

Opposite, Leydig cells from hypogonadotropic-hypogonadal rats characterized by low LH-cAMP, testosterone, and ATP production, reduced markers of mitogenesis and mitofusion (Mfn1/2, Opa1) associated with reduced mtDNA content.

Altogether results underline LH-cAMP signaling as an important regulator of mitochondrial physiology arranging mitochondrial dynamics, bioenergetic and steroidogenic function in Leydig cells.

Medar MLJ, Marinkovic DZ, Kojic Z, Becin AP, Starovlah IM, Kravic-Stevovic T, Andric SA, Kostic TS. Dependence of Leydig Cell's Mitochondrial Physiology on Luteinizing Hormone Signaling. Life (Basel). 2020 Dec 31;11(1):E19. doi: 10.3390/life11010019. PMID: 33396202. https://www.mdpi.com/2075-1729/11/1/19/htm

 

[Michael Scally MD]

Leydig Cell Aging: Molecular Mechanisms and Treatments

Late-onset hypogonadism, resulting from deficiency in serum testosterone (T), affects the health and quality of life of millions of aging men.

T is synthesized by Leydig cells (LCs) in response to luteinizing hormone (LH).

LH binds LC plasma membrane receptors, inducing the formation of a supramolecular complex of cytosolic and mitochondrial proteins, the Steroidogenic InteracTomE (SITE).

SITE proteins are involved in targeting cholesterol to CYP11A1 in the mitochondria, the first enzyme of the steroidogenic cascade.

Cholesterol translocation is the rate-determining step in T formation. With aging, LC defects occur that include changes in SITE, an increasingly oxidative intracellular environment, and reduced androgen formation and serum T levels.

T replacement therapy (TRT) will restore T levels, but reported side effects make it desirable to develop additional strategies for increasing T.

One approach is to target LC protein-protein interactions and thus increase T production by the hypofunctional Leydig cells themselves.

Papadopoulos V, Zirkin BR. Chapter Twenty-Two - Leydig cell aging: Molecular mechanisms and treatments. In: Litwack G, ed. Vitamins and Hormones: Academic Press; 2021:585-609. Leydig cell aging: Molecular mechanisms and treatments

 

[BirdieNumNum]

Do my new leydig have a new expiry date?