Endocrine Abstracts

JOINT369

Introduction: The vitamin A derivative, isotretinoin, is known for its efficacy in the treatment of acne vulgaris. Isotretinoin use among young men is increasing. In 2023, the number of users in Denmark had risen to 10,015 (3.40 per 1,000), with the highest incidence observed among men aged 18–24-years (12.51 per 1,000). Isotretinoin is a stereoisomer of retinoic acid, which has a crucial role in spermatogenesis. Recent studies on isotretinoin exposure and male fertility remain inconclusive, suggesting both positive and negative effects. Therefore, we aimed to further investigate the potential side-effects of isotretinoin on male reproductive health.

Methods: The effects of isotretinoin and retinoic acid were investigated 1) in vitro on human sperm cells using a Ca²⁺-fluorometric assay, and 2) ex vivo in hanging drop cultures of human testis tissue (for 96 hours). Germ cell proliferation and apoptosis in cultured testicular tissue were assessed through BrdU incorporation and c-PARP antibody detection with IHC staining. Steroid hormones, secreted by the cultured testis tissue, were measured using isotope-diluted on-line TurboFlow-LC-MS/MS, and Inhibin B was detected by ELISA. Additionally, 3) a cross-sectional analysis of the in vivo data from the Danish Young Men Study (DYMS) cohort compared reproductive hormones and semen parameters between isotretinoin users and non-users.

Results: Isotretinoin and retinoic acid (in concentrations of 12.5-100µM) induced Ca²⁺ signals and inhibited progesterone- and prostaglandin-initiated signals through the CatSper Ca²⁺ channel in sperm cells. In testicular cultures, neither isotretinoin nor retinoic acid significantly affected germ cell proliferation or apoptosis. However, assessment of hormones in the culture media revealed changes in secreted androgens, progestins and corticoids. Testosterone and androstenedione were significantly increased, while DHEAS decreased, after exposure to the highest isotretinoin concentrations (15-25 µM). Dihydrotestosterone (DHT) and inhibin B were significantly decreased under varying isotretinoin and retinoic acid concentrations (10-25µM). Progesterone and 17-hydroxypregnenolone increased across all isotretinoin and retinoic acid concentrations (10-25 µM), as did the corticoids, 11-deoxycorticosterone (DOC) and 11-deoxycortisol (11-DOC). Analysis of the DYMS cohort revealed significantly higher estradiol in isotretinoin users (n = 51) compared to non-users (n = 6,498), but no differences in semen parameters.

Conclusion: Our preliminary results indicate effects of isotretinoin on several male reproductive parameters. To establish its definitive role, further in vitro and ex vivo studies are needed, alongside more comprehensive investigations of the in vivo DYMS cohort data. These efforts are crucial to determining the potential side-effects of isotretinoin on male reproductive functions.