Myostatin (GDF-8) inhibits the activation, proliferation, and differentiation of myogenic satellite cells. The relative importance of this growth factor is demonstrated in myostatin-null mice and cattle possessing defective myostatin genes. These defects result in greatly enhanced musculature. In the present study, the effect of myostatin on chicken myogenic satellite cells derived from two different skeletal muscles was studied. The effect of anti-myostatin antibodies on cellular responses was also examined. Satellite cells isolated from the pectoralis major (PM) muscles were more responsive to the proliferation depressing effects of myostatin compared to cells from the biceps femoris (BF; P <or= 0.05). Myostatin inhibited differentiation of satellite cells derived from the PM muscle (P <or=0.05), but had no effect on cells from the BF (P >or=0.05). Myostatin administered to proliferating cells depressed the synthesis of decorin (P <or= 0.05), an extracellular matrix proteoglycan. However, in differentiating cultures, only BF cells expressed lower levels of decorin (P <or= 0.05). Decorin expression in PM cells was unchanged (P>or= 0.05). Administration of anti-myostatin antibodies to proliferating cultures increased cell proliferation by 6-7% over 3 days. There was no effect on differentiation of either PM or BF cells. The present study demonstrates that there are differences in the responsiveness to myostatin of chicken satellite cells derived from different muscles. Evidence is also given to support the role of endogenous myostatin in autocrine regulation of muscle growth.