17β-Estradiol Promotes Schwann Cell Proliferation and Differentiation, Accelerating Early Remyelination in a Mouse Peripheral Nerve Injury Model

Figure 3

E2 treatment upregulated AKT/mTOR signaling in Schwann cells. (a) Immunostaining for the expression of pS6 (red signal) in the longitudinal section of the nerve bridge from the mouse sciatic nerve 12 days after injury. Sox10 (green signal) was costained to illustrate Schwann cell linage cells. More pS6-positive cells were detected in the E2-treated nerve bridge than in the control. Scale bars represent 60 M (400x). (b) Western blot analysis for MBP, total AKT, p-AKT (S473), pS6, and p-mTOR from tissue lysates to study AKT/mTOR signaling in nerve bridge site. The western blot analysis of the nerve bridge tissue also revealed higher phosphorylated AKT (p-AKT), pS6, and p-mTOR levels in the hormone-treated mice than in the control mice. (c–f) Quantification of the relative expression intensities of MBP, p-AKT (S473), pS6, and p-mTOR calculated from (b) (; , ). (g) Western blot analysis for total AKT and p-AKT (S473) expressions in primary Schwann cells treated with E2 for 0 min, 30 min, 60 min, 2 h, 12 h, and 24 h. (h) Western blot analysis for total AKT, p-AKT (S473), and pS6 expression in primary Schwann cells treated with E2, E2+MK2206, or DMSO for only 60 min. (i, j) Quantification of relative AKT and p-AKT (S473) expression intensities calculated from (g) (; , E2 60 min versus DMSO; E2 2 h versus DMSO). (k, l) Quantification of relative p-AKT (S473) and pS6 expression intensities calculated from (h) (; ). AKT, protein kinase B; DMSO, dimethyl sulfoxide; MBP, myelin basic protein; NF, neurofilament; p-mTOR, mammalian target of rapamycin.

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