Immunohistochemical analysis of activin A expression in spinal cords of rats with clip compression injuries

Activin A, a member of the TGF-β superfamily, plays roles in neuroprotection and immunomodulation. In the present study, activin A expression was investigated on days 1, 4 and 7 post-injury in female adult Sprague-Dawley rats with spinal cord injuries (SCIs). The spinal cord was compressed with a vascular clip for 1 min following laminectomy at T9/T10. Western blot analysis showed that activin A levels peaked in SCI core lesions 4 days post-injury (p < 0.01) and fell thereafter until day 7. Immunohistochemically, activin A was constitutively expressed in vascular endothelial cells, astrocytes and neurons of sham-operated controls, and in macrophages and reactive astrocytes of lesional cores and peripheries. As activin A plays an immunomodulatory role in the early stages of SCI and facilitates behavioral improvement, we postulate that transient upregulation of activin A in SCI tissue may contribute to modulation of inflammation development during SCI, thus leading to neuroprotection.