Related Experiment Video
Updated: Jun 12, 2026
Establishment of Rat Models Mimicking Gender-affirming Hormone Therapies
Published on: January 10, 2025
Dose-dependent increase in intratesticular testosterone by very low-dose human chorionic gonadotropin in normal men
1Department of Medicine, University of Washington, 1959 NE Pacific Street, Box 357138, Seattle, Washington 98195, USA. mylang@u.washington.edu
Context And Objective:
In men with infertility secondary to gonadotropin deficiency, treatment with relatively high dosages of human chorionic gonadotropin (hCG) stimulates intratesticular testosterone (IT-T) biosynthesis and spermatogenesis. Previously we found that lower dosages of hCG stimulated IT-T to normal. However, the minimal dose of hCG needed to stimulate IT-T and the dose-response relationship between very low doses of hCG and IT-T and serum testosterone in normal men is unknown.
Design, Setting, Patients, And Intervention:
We induced experimental gonadotropin deficiency in 37 normal men with the GnRH antagonist acyline and randomized them to receive one of four low doses of hCG: 0, 15, 60, or 125 IU sc every other day or 7.5 g daily testosterone gel for 10 d. Testicular fluid was obtained by percutaneous aspiration for steroid measurements at baseline and after 10 d of treatment and correlated with contemporaneous serum hormone measurements.
Results:
Median (25th, 75th percentile) baseline IT-T was 2508 nmol/liter (1753, 3502 nmol/liter). IT-T concentrations increased in a dose-dependent manner with very low-dosage hCG administration from 77 nmol/liter (40, 122 nmol/liter) to 923 nmol/liter (894, 1017 nmol/liter) in the 0- and 125-IU groups, respectively (P<0.001). Moreover, serum hCG was significantly correlated with both IT-T and serum testosterone (P<0.01).
Conclusion:
Doses of hCG far lower than those used clinically increase IT-T concentrations in a dose-dependent manner in normal men with experimental gonadotropin deficiency. Assessment of IT-T provides a valuable tool to investigate the hormonal regulation of spermatogenesis in man.
Related Concept Videos
01:26Testosterone: Functions and Regulation
01:23Infertility in Males
01:24Gonadal and Placental Hormones
In males, testosterone is the primary gonadal androgen. It plays a central role in the maturation of male reproductive organs — the penis and testes. Additionally, testosterone is instrumental in the development of secondary sexual characteristics — a deep voice as well as facial and pubic hair growth — and...
01:41Spermatogenesis
01:19Testes: Gross Anatomy
Each testis is surrounded by the tunica albuginea, a dense connective tissue layer that provides structural support and protection. This layer is covered by an outer serous membrane called the tunica vaginalis, which helps reduce friction...
01:22Target Cell Response to Hormones
Notably, the cellular response can be regulated by altering the number of receptors expressed in the cell. For example, prolonged exposure to elevated hormone levels results in a gradual decline or down-regulation in the number of receptors for that specific hormone on the cell surface. Conversely, in response to low hormone levels, cells may use up-regulation, producing an...