Improved impedance to maladaptation and enhanced VCAM-1 upregulation with resistance-type training in the long-lived Snell dwarf (Pit1dw/dw) mouse

Abstract

Snell dwarf mice with the Pit1 dw/dw mutation are deficient in growth hormone, prolactin, and thyroid stimulating hormone and exhibit >40% lifespan extension. This longevity is accompanied by compromised muscular performance. However, research regarding young (3-month-old) Snell dwarf mice demonstrate exceptional responsivity to resistance-type training especially in terms of a shifted fiber type distribution and increased protein levels of vascular cell adhesion molecule-1 (VCAM-1), a possible mediator of such remodeling. In the present study, we investigated whether this responsiveness persists at 12 months of age. Unlike 12-month-old control mice, age-matched Snell dwarf mice remained resistant to training-induced maladaptive decreases in performance and muscle mass. This was accompanied by retainment of the remodeling capacity in muscles of Snell dwarf mice to increase VCAM-1 protein levels and a shift in myosin heavy chain (MHC) isoform distribution with training. Even decreasing training frequency for control mice, an alteration which protected muscles from maladaptation at 12 months of age, did not result in the overt remodeling observed for Snell dwarf mice. The results demonstrate a distinct remodeling response to resistance-type exercise operative in the context of the Pit1 dw/dw mutation of long-lived Snell dwarf mice.

Preclinical assessment of rodent jumping power with a novel electrical stimulation-assisted device

“…However, the existing preclinical research tools for muscle function assessment, such as the rotarod, grip strength, hanging wire, and treadmill, have limitations involving measuring low-intensity simple movements, learning effects, evaluator subjectivity, and limited power indicators 16 . Additionally, while the measurement of force and torque output through direct electrical stimulation of muscles can exhibit the muscle quality 17 – 19 , they are invasive methods which can pose constraints on the extent of further research. Therefore, it is necessary to develop a new muscle functional assessment tool that can overcome these limitations and accurately evaluate muscle function in preclinical research.…”