Sex differences of steroid receptor coactivator-1 expression after spinal cord injury in mice

Objective: The neural functional recovery of female is often better than that of male after spinal cord injury (SCI). Evidences show that estrogen can attenuate inflammation and promote the neural survival and regeneration after SCI. SRC-1 is an essential initiation factor for the estrogen-regulated target gene transcription and plays a key role in regulating estrogen activity. However, it is not known whether and how SRC-1 mediates the neural regeneration promoted by estrogen after SCI. Study of the sex differences and changes of SRC-1 expression after SCI will be helpful to understand the above questions. Methods: In this study, the sex differences of expressions of SRC-1 and cytoskeleton-associated protein Profilin-1 in normal and SCI mice were detected by immunohistochemistry at 1-, 3-, and 7 days after injury, respectively. Results: Although the SRC-1 expression in female mice was lower than that in males under normal conditions, its expression in females was more dominant after SCI. The expression of Profilin-1 in both sexes increased first, and then decreased at 3 days after injury. However, there was a second increase in females at 7 days after injury. Conclusion: Our study suggests that the more SRC-1 expression in females after SCI may play a role in improving the efficiency of estrogen function and thus, promote regeneration better. SRC-1 may also participate in the regulation of Profilin-1 in spinal cord, which is important in the assembly and extension of the axonal cytoskeleton during regeneration after SCI.