Nandrolone decanoate increases satellite cell numbers in the chicken pectoralis muscle

Abstract

The anabolic androgenic steroid nandrolonedecanoate has minimal androgenic effects and, thus, iswidely used to induce muscle hypertrophy in bothpatients and athletes. Although increases in satellite cellnumbers and satellite cells giving rise to new myonucleiare associated with hypertrophy in many experimentalmodels, the relationship between nandrolone andsatellite cells is poorly understood. Here we test thehypothesis that nandrolone administration is associatedwith an increase in satellite cell numbers in muscle.Nandrolone was injected at weekly intervals for fourweeks into the right pectoralis muscle of female whiteleghorn chickens aged 63 days post hatch. Age/size/sexmatched control birds received saline injections. Thecontralateral pectoralis was excised for study from eachcontrol and nandrolone treated bird. An antibody againstPax7 and immunocytochemical techniques were used toidentify satellite cells. Nandrolone significantlyincreased mean pectoralis mass by approximately 22%,and mean fiber diameter by about 24%. All satellite cellindices that were quantified increased significantly inchicken pectoralis with administration of nandrolone.Nandrolone injected birds had on average higher satellitecell frequencies (#SC nuclei/all nuclei within basallamina), number of satellite cells per millimeter of fiber,and satellite cell concentrations (closer together).Myonuclei were further apart (less concentrated) innandrolone injected muscle. However, an overallincrease in myonuclear numbers was revealed by asignificantly greater mean number of myonuclei permillimeter of fiber in nandrolone injected muscle. Ourresults suggest that satellite cells may be key cellular vectors for nandrolone induced muscle fiberhypertrophy.