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Microdialysis-Assessed Exercised Muscle Reveals Localized and Differential IGFBP Responses to Unilateral Stretch
Bradley C Nindl1,2,3, Juha Ahtiainen4, Sheila S Gagnon4
1Neuromuscular Research Laboratory/Warrior Human Performance Research Center, University of Pittsburgh, Pittsburgh, PA, United States.
Frontiers in Endocrinology
|June 18, 2020
Summary
Unilateral exercise alters the Insulin-like Growth Factor-I (IGF-I) system in muscle interstitial fluid, increasing IGFBP-3 and IGFBP-4 while decreasing IGFBP-5. This localized muscle response differs from systemic changes observed in serum.
Area of Science:
- Exercise Physiology
- Endocrinology
- Muscle Metabolism
Background:
- Microdialysis offers unique insights into local muscle metabolism, complementing systemic blood measurements.
- The Insulin-like Growth Factor-I (IGF-I) system plays a crucial role in muscle adaptation and repair.
- Understanding localized IGF-I system regulation during exercise is vital for optimizing training and recovery.
Purpose of the Study:
- To investigate differential regulation of the IGF-I system in interstitial fluid during unilateral stretch shortening cycle (SSC) exercise.
- To compare local muscle responses with systemic changes in serum IGF-I parameters.
Main Methods:
- 10 men performed unilateral SSC exercise to fatigue.
- Serum and muscle interstitial fluid (via microdialysis) samples were collected pre-, during, and post-exercise.
- Measurements included total and free IGF-I, and IGF-binding proteins (IGFBPs 1-6) using immunoassays.
Main Results:
- Serum total IGF-I and IGFBP-1, -3 increased post-exercise, while IGFBP-6 decreased.
- Muscle interstitial fluid showed no change in free IGF-I but significant alterations in IGFBPs.
- Localized exercise increased interstitial IGFBP-3 and IGFBP-4, and decreased IGFBP-5 in the exercised leg.
Conclusions:
- Unilateral exercise induces distinct IGF-I system regulation locally within muscle and systemically in serum.
- This study is the first to demonstrate localized increases in muscle interstitial IGFBP-3 and IGFBP-4, and decreases in IGFBP-5 following exercise.
- Findings highlight the importance of microdialysis for understanding exercise-induced molecular events in muscle tissue.
