A Groundbreaking Study on Myostatin and FSH
Let’s talk about a new study from Science that caught my eye—not just because it’s elegant science, but because it changes how we think about fertility hormones. The research by Ongaro et al. (2025) uncovers something surprising: that your muscles may be helping regulate your fertility. Specifically, the hormone myostatin, best known for limiting muscle growth, turns out to play a big role in making follicle-stimulating hormone (FSH), which is key for both female and male fertility.
Wait, What Is Myostatin Again?
Myostatin is a hormone produced by skeletal muscle. Its main job is to stop muscle cells from growing too big. Bodybuilders who lack functional myostatin can build much larger muscles—and certain rare genetic mutations that affect myostatin can result in “super-muscled” animals (and humans too).
Until now, we thought myostatin’s effects were mostly limited to muscle size and metabolism. But this study shows it’s also a powerful endocrine (hormone-producing) player, traveling through the bloodstream to affect the brain’s pituitary gland—where FSH is made.
What the Researchers Did
This wasn’t just a one-method study. The team used mouse models, pituitary cell cultures, and gene expression analysis to track the pathway from muscle to hormone. They specifically knocked out the myostatin gene in muscle tissue and found that the mice had significantly lower FSH levels. That’s a big deal.
They also showed that introducing myostatin to cultured pituitary cells increased expression of the Fshb gene—the blueprint for making FSH. And when they blocked the receptor for myostatin (called ActRIIB), FSH levels dropped. It’s a direct line: muscle → myostatin → pituitary → FSH.
Why FSH Matters for Fertility
FSH is one of the key reproductive hormones. In women, it helps follicles grow and mature, eventually triggering ovulation. In men, it supports the production of sperm. Low FSH can mean poor ovarian response, irregular cycles, or even infertility. And in men, it can lead to reduced sperm count.
We’ve always focused on the brain’s control of FSH via GnRH (gonadotropin-releasing hormone). But this study shows we’ve been missing a piece of the puzzle: muscle itself is involved in regulating FSH levels. That’s a paradigm shift.
What This Means for You (and for Fertility Care)
This research opens up some fascinating possibilities. Could increasing muscle mass, or modifying myostatin activity, help optimize FSH levels and fertility? Could people with low muscle mass—like those who are underweight or sedentary—have lower FSH because of less myostatin? Could myostatin-targeting drugs (which are already being tested for muscle diseases) one day be used to tweak reproductive hormones?
We don’t have clinical applications yet, but it’s not a stretch to imagine fertility clinics one day measuring myostatin or even prescribing resistance training not just for general health, but as part of fertility protocols.
Takeaways for Now
- Muscles aren’t just for strength—they’re hormone factories that can influence your reproductive system.
- Myostatin, once thought to only affect muscle size, is now known to help drive the production of FSH, a hormone critical for fertility.
- This could help explain why exercise (especially resistance training) is linked to better reproductive outcomes—not just through weight regulation or insulin sensitivity, but through direct hormonal effects.
- The research also adds a whole new layer to how we think about hormone dysfunction and fertility treatment, especially in people with unexplained low FSH.
This kind of study reminds us that the body works in systems, not silos—and that when it comes to fertility, we may need to start thinking more holistically, muscle tissue included.
Reference:
- Luisina Ongaro, Xiang Zhou, Ying Wang, Hailey Schultz, Ziyue Zhou, Evan R. S. Buddle, Emilie Brûlé, Yeu-Farn Lin, Gauthier Schang, Adam Hagg, Roselyne Castonguay, Yewei Liu, Gloria H. Su, Nabil G. Seidah, Kevin C. Ray, Seth J. Karp, Ulrich Boehm, Frederique Ruf-Zamojski, Stuart C. Sealfon, Kelly L. Walton, Se-Jin Lee, Daniel J. Bernard. Muscle-derived myostatin is a major endocrine driver of follicle-stimulating hormone synthesis. Science, 2025; 387 (6731): 329 DOI: 10.1126/science.adi4736
Dr Marina OBGYN