High-Frequency Stimulation on Skeletal Muscle Maintenance in Female Cachectic Mice.

Cancer cachexia, an unintentional body weight loss due to cancer, affects patients' survival, quality of life, and response to chemotherapy. Although exercise training is a promising intervention to prevent and treat cancer cachexia, our mechanistic understanding of cachexia's effect on contraction-induced muscle adaptation has been limited to the examination of male mice. Because sex can affect muscle regeneration and response to contraction in humans and mice, the effect of cachexia on the female response to eccentric contraction warrants further investigation.
PURPOSE: The purpose of this study was to determine whether high-frequency electric stimulation (HFES) could attenuate muscle mass loss during the progression of cancer cachexia in female tumor-bearing mice.
METHODS: Female wild-type (WT) and Apc (Min) mice (16-18 wk old) performed either repeated bouts or a single bout of HFES (10 sets of 6 repetitions, ~22 min), which eccentrically contracts the tibialis anterior (TA) muscle. TA myofiber size, oxidative capacity, anabolic signaling, and catabolic signaling were examined.
RESULTS: Min had reduced TA muscle mass and type IIa and type IIb fiber sizes compared with WT. HFES increased the muscle weight and the mean cross-sectional area of type IIa and type IIb fibers in WT and Min mice. HFES increased mTOR signaling and myofibrillar protein synthesis and attenuated cachexia-induced AMPK activity. HFES attenuated the cachexia-associated decrease in skeletal muscle oxidative capacity.
CONCLUSION: HFES in female mice can activate muscle protein synthesis through mTOR signaling and repeated bouts of contraction can attenuate cancer-induced muscle mass loss.