Date Thesis Awarded

4-2014

Document Type

Honors Thesis

Degree Name

Bachelors of Science (BS)

Department

Kinesiology & Health Sciences

Advisor

Brennan Harris

Committee Member

Randolph Coleman

Committee Member

Scott Ickes

Abstract

Previously, we have demonstrated a dramatic increase in mitochondrial biogenesis in skeletal muscle of rats exercise trained while maintaining a constant core temperature. In this study, we explored the potential mechanisms of increased mitochondrial biogenesis in this model by examining the expression of PGC-1α, AMPK, eNOS, SIRT1 and SIRT3. Female, Sprague-Dawley rats (5 mos of age) were divided into three groups sedentary (S), exercise in 22°C room (ET), and exercise while maintaining core temperature (E). Exercised animals trained for 5 weeks on a motor-driven treadmill at 30 m/min, 60 min/day, and 5 days/wk during the final 2 weeks. Core temperature was held constant in E by reducing room temperature to 6-8°C. Mitochondrial biogenesis was increased in cold-trained animals versus room temperature-trained animals as indicated by a significant (P<0.05) increase in cytochrome oxidase activity in the cold training group. Hsp70 expression was significantly (P< 0.05) increased in both ET and E rats versus SED, but ET was also significantly (P< 0.05) higher than the E group. Cold training was also less stressful than regular exercise; serum LDH was significantly (P< 0.05) elevated among ET tissues versus E tissues. There was no difference in PGC-1α, AMPK, or eNOS expression between any of the groups. SIRT1 was significantly (P< 0.05) decreased in rats trained at room temperature (ET), but unchanged in cold-trained rats (E). SIRT3 expression was significantly (P< 0.05) increased in rats trained at both room temperature and between 6-8°C, but no difference was observed between the two. The results of this study indicate that the effect of core temperature alters the pathway by which mitochondrial biogenesis occurs.

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