CB1 Receptors Help Maintain the Blood-Testis Barrier During Sperm Production | Research

The takeaway

Deleting the CB1 cannabinoid receptor in mice disrupted the blood-testis barrier, causing blood cells to infiltrate the testes and slowing sperm production.

Researchers studying cannabinoid effects on male fertility and anyone interested in how the endocannabinoid system maintains biological barriers.

CB1 deletion caused blood cell infiltration into seminiferous tubules

What the researchers found

CB1 knockout mice showed disrupted expression of blood-testis barrier components and infiltration of blood cells into seminiferous tubules, specifically at the Stage VIII-IX transition of the sperm production cycle. Loss of CB1 increased the rate of tight junction internalization and degradation, leading to premature passage of germ cells and slower spermatogenesis.

Why it matters

The blood-testis barrier protects developing sperm from the immune system. This study reveals that the endocannabinoid system plays a previously unknown role in maintaining this barrier, which could have implications for understanding how cannabis use affects male fertility.

The numbers in context

Blood cell infiltration occurred specifically at the Stage VIII-IX transition. CB1 deletion increased kinetics of tight junction internalization and recycling while promoting proteasome-mediated occludin degradation. VDAC expression (mitochondrial mass marker) remained unchanged.

How the study worked

Researchers used CB1 knockout male mice to study blood-testis barrier integrity during the seminiferous epithelium remodeling phase (Stages VIII-XI). They performed gene expression analysis of tight junction components, tracked occludin trafficking to endosomes and proteasomes, and assessed barrier permeability at different stages of the sperm cycle.

What this study cannot tell us

Complete genetic knockout of CB1 is more extreme than any level of cannabis use. The effects of partial CB1 modulation from cannabis exposure may differ significantly. This is a mouse study, and human testicular physiology has some differences.

How to read the evidence

Animal knockout study provides strong mechanistic evidence for CB1 involvement in blood-testis barrier maintenance but cannot predict the magnitude of effects from cannabis use in humans.

When this study was published

Published in 2025.

The bigger picture

The endocannabinoid system is already known to modulate the blood-brain barrier and gut barrier. This study adds the blood-testis barrier to the list, suggesting CB1 receptors play a broad role in maintaining biological barriers throughout the body.

Questions still open

Does chronic cannabis use partially impair the blood-testis barrier in humans? Could this mechanism contribute to the reduced sperm quality observed in some cannabis users?

Common questions

What is the blood-testis barrier?

It is a physical barrier formed by tight junctions between Sertoli cells that protects developing sperm from immune system attack. Without it, the body would recognize sperm as foreign and mount an immune response against them.

Does this mean cannabis reduces fertility?

This study used mice with completely deleted CB1 receptors, which is far more extreme than cannabis use. However, it identifies a mechanism through which heavy cannabis use could theoretically impair the barrier and affect sperm development.

Read the original research

Cannabinoid Receptors Modulate Physiological Remodelling of the Blood-Testis Barrier.

Journal of cellular physiology, 240(11), e70109

View on PubMed ↗Publisher’s paper ↗

Citation

Manfrevola, Francesco; Ricci, Giulia; Suglia, Antonio; Mele, Vincenza Grazia; Migliaccio, Antonella; Chianese, Rosanna; Cobellis, Gilda; Chioccarelli, Teresa. (2025). Cannabinoid Receptors Modulate Physiological Remodelling of the Blood-Testis Barrier.. Journal of cellular physiology, 240(11), e70109. https://doi.org/10.1002/jcp.70109