Ibuprofen inhibits skeletal muscle hypertrophy in rats

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Med Sci Sports Exerc. 2006 May;38(5):840-6.

Ibuprofen inhibits skeletal muscle hypertrophy in rats.

Soltow QA, Betters JL, Sellman JE, Lira VA, Long JH, Criswell DS.

Center for Exercise Science, University of Florida, Gainesville, FL.

PURPOSE:: We sought to determine whether cyclooxygenase (COX)

activity is necessary for overload-induced growth of adult rat

skeletal muscle, and whether nitric oxide synthase (NOS) activity is

involved in upregulation of COX messenger RNA (mRNA) expression in

skeletal muscle.

METHODS:: Unilateral surgical removal of the gastrocnemius and soleus

was performed on the right hindlimb of 16 female Sprague-Dawley rats

(~230 g) to induce chronic overload (OL) of the plantaris for 14 d,

with sham surgeries performed on the contralateral leg as a normally

loaded (NL) control. Half of the rats were treated with the

nonspecific COX inhibitor, ibuprofen (0.2 mg.mL in drinking water;

~20 mg.kg.d). In a second experiment, the plantaris was unilaterally

overloaded for 5 or 14 d in male rats (~350 g; N = 16 rats per time

point) and half of the animals were treated with the NOS inhibitor, L-

NAME (0.75 mg.mL in drinking water; ~90 mg.kg.d).

RESULTS:: Ibuprofen treatment inhibited plantaris hypertrophy by

approximately 50% (P < 0.05) following 14 d of OL, as did L-NAME

treatment (P < 0.05). COX-1 and COX-2 mRNA did not differ between any

groups at 5 d. At 14 d, however, L-NAME caused a 30-fold increase in

plantaris COX-1 mRNA expression independent of loading condition.

Additionally, OL induced a 20-fold increase in COX-2 mRNA expression

compared with NL (P < 0.05) at 14 d, without affecting COX-1 mRNA

level. L-NAME treatment significantly inhibited OL-induced expression

of COX-2 mRNA.

CONCLUSION:: COX activity is important for in vivo muscle

hypertrophy, and plantaris overload is associated with NOS activity-

dependent COX-2 expression.