testosterone

Overview

Testosterone is a steroid hormone and androgen that plays a central role in male sexual development, reproductive physiology, and the maintenance of secondary sexual characteristics. It is produced primarily in the testes by Leydig cells, with smaller amounts arising from the ovaries and adrenal glands. Biologically, testosterone acts through the androgen receptor to regulate gene expression in diverse tissues, influencing muscle and bone mass, erythropoiesis, libido, spermatogenesis, and aspects of metabolic and immune function.

In biomedical research, testosterone is also studied as a circulating biomarker and as a mechanistic mediator of disease heterogeneity. Recent work has linked testosterone to endocrine, metabolic, reproductive, oncologic, and immunologic contexts, including type 1 diabetes endotypes, prostate cancer treatment response, infection-related immune modulation, and age-associated physiological profiles. Its effects are often interpreted alongside related hormones and pathways such as 17β-estradiol, growth hormone, IGF1, salivary cortisol, and inflammatory mediators including IL17A, IL18, and TLR4.

Focus of Latest Publications

Recent publications have used testosterone as a biomarker, mechanistic variable, or therapeutic context across several disease areas.

In a study of polycythemia in males living with HIV after dolutegravir and long-term antiretroviral therapy, proposed mechanisms for the observed hematologic changes included ART-associated increases in testosterone levels, along with enhanced erythropoietin production, reduced haemolysis, and improved bone marrow function. In this context, testosterone was considered part of a broader endocrine explanation for altered red cell mass in the setting of HIV infection and antiretroviral treatment.

In reproductive biology, testosterone was measured as an outcome in several animal studies. Nano-encapsulated vitamin D3 supplementation in breeding White King pigeons improved reproductive performance and egg quality, and also increased plasma testosterone alongside luteinizing hormone and estradiol, while improving antioxidant enzyme activity and lowering malondialdehyde. This suggests a link between nutritional supplementation, endocrine status, and oxidative stress in avian reproduction.

A separate study in diabetic male rats examined zingerone as a protective agent against reproductive damage. In male Sprague Dawley rats, zingerone reduced glucose and oxidative stress markers while markedly enhancing body weight, testosterone, glutathione content, antioxidant enzyme activity, and expression of the Sirt1/Nrf2/HO-1 signaling pathway, with concurrent improvement in the Bax/Bcl-2 balance. Here, testosterone served as a key indicator of testicular and reproductive recovery in a diabetes-associated injury model.

Testosterone also appeared in studies of gonadal manipulation and sex differentiation. Following orchiectomy, testosterone was discussed in relation to electrocardiographic repolarization, with the report noting that testosterone has been associated with shorter QT intervals. This supports the concept that androgen status can influence cardiac electrophysiology. In Nile tilapia, discrete anastrozole immersion produced all-male populations; aromatase inhibition was confirmed by reduced estradiol and increased testosterone, illustrating how blocking estrogen synthesis shifts the sex steroid balance toward androgen dominance.

In cancer research, testosterone was evaluated in nonmetastatic high-risk prostate cancer as a predictive biomarker for treatment benefit. One study assessed whether baseline testosterone group status, low versus normal, modified the mortality benefit of adding docetaxel to radiation therapy and androgen deprivation therapy. This reflects the clinical importance of testosterone in prostate cancer stratification and treatment response, especially in the setting of (chemo)radiotherapy and ADT.

Testosterone was also implicated in immune regulation. In acute Trypanosoma cruzi infection, androgen-mediated immunosuppression was reported to impair the effectiveness of the immune response, with testosterone described as a gonadal hormone known to modulate immunity and potentially influence infection severity. Related immunology work also examined testosterone in the context of neutrophil immunophenotype, indicating interest in how androgen exposure may affect innate immune cell behavior, including CD molecules associated with neutrophil function.

In developmental and pediatric research, testosterone showed a moderate positive association with height in children with short stature, based on analysis of 2396 children and Pearson correlation coefficient testing. This suggests that testosterone-related endocrine status may be associated with growth patterns in pediatric populations, although the publication context provided here does not establish causality.

Testosterone has also been studied in metabolic and systems biology settings. In type 1 diabetes, multi-omics analysis identified testosterone as one of the metabolites differing across age-related endotypes, with testosterone enriched in the inflammatory endotype. Another systems-level study of testosterone-related biomarkers reported that serum total testosterone interacts with multiple physiological systems and is implicated in heterogeneous aging processes in men, with links to inflammation and renal function. These findings place testosterone within broader metabolomic and biomarker networks rather than as an isolated hormone.

Additional research has explored testosterone-modified drug delivery systems. A testosterone-modified liposome loaded with a Zn-polyphenol complex was developed for treatment of male infertility, indicating interest in testosterone as a targeting moiety or surface modifier in nanomedicine. This approach aligns with the hormone’s relevance to reproductive tissues and male reproductive disorders.

Finally, a study of reproductive performance in breeding pigeons and another on all-male tilapia production both reinforce testosterone’s role as a central endocrine readout in reproductive physiology. Across these studies, testosterone was repeatedly linked to gonadal function, fertility, oxidative stress, and sex steroid balance.