PP084 - RESISTANCE TRAINING ENHANCES VITAMIN D RECEPTOR EXPRESSION AND ANABOLIC SIGNALING IN RAT SKELETAL MUSCLE

PP084

RESISTANCE TRAINING ENHANCES VITAMIN D RECEPTOR EXPRESSION AND ANABOLIC SIGNALING IN RAT SKELETAL MUSCLE

R. Mori^1,*, K. Uemichi², S. Fujita¹

¹ Col. of Sport and Health Sci., ²Res. Org. of Sci. and Tech., Ritsumeikan University, Kusatsu, Japan

Rationale: Vitamin D plays a crucial role in musculoskeletal health, including regulation of skeletal muscle mass and function. We have previously revealed that an acute bout of resistance exercise transiently increased intramuscular vitamin D receptor (VDR) expression without altering circulating 25(OH)D levels, suggesting a contraction-induced regulatory mechanism (Makanae, Y. et al., 2015). However, it remains unclear whether repeated resistance exercise leads to sustained upregulation of vitamin D signaling after training.

Methods: Male rats underwent chronic resistance training induced by percutaneous electrical stimulation three times per week for four weeks. One hindlimb was subjected to maximal isometric contractions, while the contralateral limb served as an internal control. Skeletal muscle samples were collected to assess vitamin D and protein synthesis signaling-related proteins.

Results: After 4 weeks of resistance training, the gastrocnemius muscle mass and maximal isometric torque, were significantly higher compared to control by 4% and 35%, respectively (p < 0.05). Importantly, VDR protein expression was upregulated in trained muscle, with concomitant enhanced expression of proteins associated with protein synthesis signaling.

Conclusion: Resistance training induces upregulation of vitamin D signaling in skeletal muscle, characterized by increased VDR expression, muscle hypertrophy, and strength gains. These findings suggest a potential role for VDR as a molecular mediator linking mechanical loading to anabolic adaptations, and provide new insights into how vitamin D signaling contributes to exercise-induced muscle adaptation.

References: Makanae, Y., et al. Acute bout of resistance exercise increases vitamin D receptor protein expression in rat skeletal muscle. Experimental physiology, 2015, 100.10: 1168-1176.

Disclosure of Interest: None declared