Phenotypic and molecular differences between rats selectively bred to voluntarily run high vs. low nightly distances.

Roberts MD, Brown JD, Company JM, Oberle LP, Heese AJ, Toedebusch RG, Wells KD, Cruthirds CL, Knouse JA, Ferreira JA, Childs TE, Brown M, Booth FW
Am J Physiol Regul Integr Comp Physiol. 2013 304 (11): R1024-35

PMID: 23552494 · PMCID: PMC3680752 · DOI:10.1152/ajpregu.00581.2012

The purpose of the present study was to partially phenotype male and female rats from generations 8-10 (G8-G10) that had been selectively bred to possess low (LVR) vs. high voluntary running (HVR) behavior. Over the first 6 days with wheels, 34-day-old G8 male and female LVRs ran shorter distances (P < 0.001), spent less time running (P < 0.001), and ran slower (P < 0.001) than their G8 male and female HVR counterparts, respectively. HVR and LVR lines consumed similar amounts of standard chow with or without wheels. No inherent difference existed in PGC-1α mRNA in the plantaris and soleus muscles of LVR and HVR nonrunners, although G8 LVR rats inherently possessed less NADH-positive superficial plantaris fibers compared with G8 HVR rats. While day 28 body mass tended to be greater in both sexes of G9-G10 LVR nonrunners vs. G9-G10 HVR nonrunners (P = 0.06), body fat percentage was similar between lines. G9-G10 HVRs had fat mass loss after 6 days of running compared with their prerunning values, while LVR did not lose or gain fat mass during the 6-day voluntary running period. RNA deep sequencing efforts in the nucleus accumbens showed only eight transcripts to be >1.5-fold differentially expressed between lines in HVR and LVR nonrunners. Interestingly, HVRs presented less Oprd1 mRNA, which ties in to potential differences in dopaminergic signaling between lines. This unique animal model provides further evidence as to how exercise may be mechanistically regulated.

MeSH Terms (24)

Absorptiometry, Photon Animals Body Composition DNA, Complementary Eating Female Hindlimb Male Muscle, Skeletal Muscle Fibers, Skeletal NAD Nucleus Accumbens Organ Size Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha Phenotype Physical Conditioning, Animal Rats Rats, Wistar Real-Time Polymerase Chain Reaction RNA, Messenger RNA-Binding Proteins Running Sex Characteristics Transcription Factors

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