Research team from the Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, Toho University — including Associate Professor Keisuke Obara, Lecturer Kento Yoshioka, and Professor Yoshio Tanaka — has discovered that docosahexaenoic acid (DHA), a major omega-3 fatty acid found in fish oil, directly relaxes smooth muscle in the male reproductive tract by blocking specific calcium channels. The findings, published in Biological and Pharmaceutical Bulletin , may help explain DHA’s broader health benefits and suggest potential new approaches to treating male infertility.
Key Findings
Broader Significance
DHA has long been associated with brain health, anti-inflammatory effects, and cardiovascular protection. This study provides new evidence that DHA’s benefits extend to reproductive health, by acting directly on the molecular machinery that controls smooth muscle contraction.
“Our results suggest TRPC3/6 channels as new molecular targets of DHA,” said Dr. Keisuke Obara , lead author and Associate Professor at Toho University. “This not only gives us a clearer understanding of how omega-3 fatty acids work in the body, but also highlights their potential for improving male reproductive health.”
Next Steps
The researchers note that further studies are needed to confirm these findings in clinical settings. Still, the concentrations of DHA used in their experiments are comparable to levels achieved through dietary supplementation, suggesting real-world relevance.
Proposed Mechanism of Action of DHA in Vas Deferens Smooth Muscle
Noradrenaline (NA) activates α 1A -adrenoceptors (α 1A -AR), driving Ca 2+ entry through two pathways that promote contraction: L-type voltage-dependent Ca 2+ channels (L-type VDCC) and TRPC3/6 channels. Acute application of docosahexaenoic acid (DHA) preferentially suppresses the TRPC3/6-mediated component (blue block), thereby reducing the residual “fast/phasic” portion of the NA-evoked contraction even when L-type channels are blocked. The net effect is diminished Ca 2+ influx and attenuation of rat vas deferens smooth muscle contraction.
Journal: Biological and Pharmaceutical Bulletin (September 30, 2025)
Title: Docosahexaenoic acid targets TRPC3/6 channels to suppress noradrenaline-induced contraction in rat vas deferens smooth muscle
Authors: Keisuke Obara, Miwa Enomoto, Mio Furuta, Haruka Okura, Ayu Kato, Taisei Mouri, Minori Gohara, Tomohiro Ura, Hiyori Nasu, Kento Yoshioka, Taichi Kusakabe, Keisuke Takahashi, Keisuke Kato, Yoshio Tanaka
DOI: 10.1248/bpb.b25-00428
Abstract URL: https://doi.org/10.1248/bpb.b25-00428
Biological and Pharmaceutical Bulletin
Experimental study
Animals
Docosahexaenoic acid targets TRPC3/6 channels to suppress noradrenaline-induced contraction in rat vas deferens smooth muscle
30-Sep-2025
The authors declare no conflict of interest.