Systemic Insulin Sensitivity and Skeletal Muscle Akt Signaling in Rats Artificially Selected for Low and High Aerobic Capacity

The mechanism(s) linking physical inactivity, obesity, and type-II diabetes are unclear. I hypothesized low intrinsic aerobic capacity is associated with reduced systemic insulin sensitivity via skeletal muscle insulin signaling. After 34 generations of selective breeding, high aerobic capacity (HCR) rats exhibited an 8-fold increase in running distance vs low aerobic capacity (LCR) rats (n=14 per group). LCR rats had higher rates of weight gain vs HCR (p<0.05) though food consumption was constant (p=0.86) over a 12-week study. Rats were divided into 4 groups: 1) LCR-Sham Surgery, 2) LCR-Catheterization, 3) HCR-Sham Surgery or 4) HCR-Catheterization (n=7 per group). Euglycemic-hyperinsulinemic clamps on catheterized rats tested insulin sensitivity while sham LCR and HCR were used for basal tissue analysis. Plasma insulin levels did not differ during the clamps, but LCR required lower glucose infusion rates than HCR (p<0.05). Upon insulin stimulation, both absolute and normalized phospho-Akt(Ser473) of soleus muscle were significantly increased in HCR above basal group (p<0.05), but not in LCR. No difference was observed between insulin-stimulated phospho-Akt(Ser473) of HCR and LCR groups . These data support that LCR is linked to a reduction in insulin sensitivity in vivo without impairments of insulin-stimulated skeletal muscle phospho-Akt(Ser473) vs HCR rats.

Name thesis:degree_name

Master of Science in Cell and Molecular Biology

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Biomedical Sciences

Year

2015

Author dc:creator

• Fulghum, Kyle Levi

Contributors dc:contributor

• Tyler Morris

• aerobic capacity
• insulin signaling
• Akt
• metabolism
• skeletal muscle
• rat
• Medical Molecular Biology

Statement dc:rights

• © Kyle Levi Fulghum

Repository record dc:identifier

https://bearworks.missouristate.edu/theses/977

OAI identifier oai:identifier

oai:bearworks.missouristate.edu:theses-1976