Lactate dehydrogenase regulation in aged skeletal muscle: Regulation by anabolic steroids and functional overload.
Aging alters the skeletal muscle response to overload-induced growth. The onset of functional overload is characterized by increased myoblast proliferation and an altered muscle metabolic profile. The onset of functional overload is associated with increased energy demands that are met through the interconversion of lactate and pyruvate via the activity of lactate dehydrogenase (LDH). Testosterone targets many of the processes activated at the onset of functional overload. However, the effect of aging on this metabolic plasticity at the onset of functional overload and how anabolic steroid administration modulates this response is not well understood. The purpose of this study was to determine if aging would alter overload-induced LDH activity and expression at the onset of functional overload and whether anabolic steroid administration would modulate this response. Five-month and 25-month male Fischer 344xF1 BRN were given nandrolone decanoate (ND) or sham injections for 14days and then the plantaris was functionally overloaded (OV) for 3days by synergist ablation. Aging reduced muscle LDH-A & LDH-B activity 70% (p<0.05). Aging also reduced LDH-A mRNA abundance, however there was no age effect on LDH-B mRNA abundance. In 5-month muscle, both ND and OV decreased LDH-A and LDH-B activity. However, there was no synergistic or additive effect. In 5-month muscle, ND and OV decreased LDH-A mRNA expression with no change in LDH-B expression. In 25-month muscle, ND and OV increased LDH-A and LDH-B activity. LDH-A mRNA expression was not altered by ND or OV in aged muscle. However, there was a main effect of OV to decrease LDH-B mRNA expression. There was also an age-induced LDH isoform shift. ND and OV treatment increased the "fast" LDH isoforms in aged muscle, whereas ND and OV increased the "slow" isoforms in young muscle. Our study provides evidence that aging alters aspects of skeletal muscle metabolic plasticity normally induced by overload and anabolic steroid administration.
Exercise Muscle Biology Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville AR 72701, United States; Integrative Muscle Biology Laboratory, Exercise Science Department, Norman J. Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States. Electronic address: tawashin@uark.edu.
Tyrone A
TA
Washington
Integrative Muscle Biology Laboratory, Exercise Science Department, Norman J. Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States.
Julie M
JM
Healey
Integrative Muscle Biology Laboratory, Exercise Science Department, Norman J. Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States.
Raymond W
RW
Thompson
Department of Biological and Physical Sciences, Benedict College, Columbia, SC 29208, United States.
Larry L
LL
Lowe
Integrative Muscle Biology Laboratory, Exercise Science Department, Norman J. Arnold School of Public Health, University of South Carolina, Columbia, SC 29208, United States.
James A
JA
Carson
D000375:Aging / Q000378:metabolism*; D045930:Anabolic Agents / Q000494:pharmacology*; D000818:Animals; D001823:Body Composition; D001835:Body Weight; D002950:Citrate (si)-Synthase / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism*; D000080864:Lactate Dehydrogenase 5; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D009277:Nandrolone / Q000031:analogs & derivatives* / Q000494:pharmacology; D000077603:Nandrolone Decanoate; D011897:Random Allocation; D011916:Rats, Inbred F344
D045930:Anabolic Agents; D007527:Isoenzymes; D009277:Nandrolone; D007770:L-Lactate Dehydrogenase; D000080864:Lactate Dehydrogenase 5; C409667:lactate dehydrogenase 1; D002950:Citrate (si)-Synthase; D000077603:Nandrolone Decanoate
Glycolysis; Hypertrophy; Lactate dehydrogenase; Metabolism; Nandrolone decanoate