Exercise Increases Mitochondrial Biogenesis in Single‐Housed Adolescent Female Rats Treated with Cocaine

Abstract

Prior studies from our laboratory showed that exercise obliterated the effects of increased anxiety induced by isolating rats during adolescence. The present study was designed to characterize the effects of treadmill running exercise on rat skeletal muscle. After weaning (day 23), male and female rats were assigned to one of the following groups: group‐housed, single‐housed, or single‐housed with exercise. Group‐housed, and isolated rats were further subdivided into saline or cocaine groups. Exercise training started the day of single housing and consisted of running on a treadmill once a day, five times a week for four weeks, and six times a week on the fifth and last week. Rats ran for 30 minutes at speed up to 10 m/min the first two weeks, 35 minutes at 12 m/min on the third week, 40 minutes at 15 m/min on the fourth week, and 45 minutes at 17 m/min on the last week. On day 59 rats were euthanized and the soleus and gastrocnemius muscles were dissected and stored at ‐80 ℃. The tissue was homogenized, DNA was isolated, and the amount of mitochondrial DNA copies was quantified using real time PCR. Our results indicate that female rats that were single‐housed showed a trend towards increased mitochondria DNA copies. However, single‐housed females that exercised and were injected with cocaine showed significantly higher copies of mitochondrial DNA in the soleus muscle than their Oil‐treated counterparts. No significant changes were observed in males.