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. Author manuscript; available in PMC: 2011 Feb 28.
Published in final edited form as: Muscle Nerve. 2010 Mar;41(3):335–341. doi: 10.1002/mus.21485

FIGURE 4.

FIGURE 4

Effect of age and IGF-1 on measures of myelination. Quantification of histologic images revealed a significant effect of IGF-1 on multiple facets of myelination and Schwann cell function. (A) Myelin thickness was significantly increased in IGF-1–treated nerves compared with saline-treated nerves. (B) Myelin thickness is known to increase with increases in axon diameter, and thus the g-ratio (axon:fiber diameter) was calculated. The significantly lower g-ratio in the IGF-1–treated groups indicates that the increases in myelination were independent of the increases in axon diameter. (C) GAP43 is a marker of Schwann cell activity and myelination. GAP43 is a marker of Schwann cell activity and myelination. mRNA for GAP43 was assayed by RT-PCR. GAP43 expression in young and aged animals was not significantly different when both were treated with saline. GAP43 expression levels were found to be significantly increased by IGF-1 treatment in both young and aged animals compared with saline treatment. The GAP43 expression in aged IGF-1–treated animals was significantly higher than in young IGF-1 animals. Data are expressed as mean ± standard error. *P < 0.05 [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]