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. 2016 May 16;6:25960. doi: 10.1038/srep25960

Figure 2. IGF-1R and IGF-2R expression was predominant in resistant oculomotor neurons and extraocular muscles.

Figure 2

Phosphorylated IGF-1R (pIGF-1R) protein was present in oculomotor motor neurons in wild-type and SOD1G93A mice (a,c,e), with signficantly lower levels in motor neurons in spinal cord in control (b) arrow heads, (e) t(113) = 8.69, n = 4 mice, P < 0.0001, Student’s t test, values represent means ± SEM) and SOD1G93A mice ((d) arrow heads, (e) t(141) = 4.30, P < 0.0001, n = 5 mice, Student’s t test, values represent means ± SEM). IGF-1R protein was strongly expressed and co-localized with endplates in extraocular muscles in wild-type and SOD1G93A mice (f,h), while it was barely detectable in lumbrical muscles (g,i). Western blot analysis confirmed that the pIGF-1R protein level was 4-fold higher in extraocular muscles than in lumbrical muscles ((j) t(8) = 8.20, n = 5 mice, P < 0.0001, Student’s t test, values represent means ± SEM). Phosphorylated IGF-2R (pIGF-2R) protein was present at comparable levels in oculomotor (k,m) and spinal (l,n) motor neurons in both wild-type ((o) t(92) = 0.6829, P = 0.4964, n = 3 mice, Student’s t test) and SOD1G93A mice ((o) t(102) = 1.880, P = 0.0630, n = 3 mice, Student’s t test). Peripherally, IGF-2R protein was barely detectable in extraocular muscles (p,r) and undetectable in lumbrical muscles (q,s) of wild-type and SOD1G93A mice using immunofluorescence. Western blot analysis showed that IGF-2R was indeed present in extraocular muscles at 3.8-fold higher levels than in lumbrical muscles ((t) t(8) = 2.86, P = 0.021, n = 5 mice/group, Student’s t test, values represent means ± SEM). Scale bars: (p) 50 μm (applicable to (a–d) and (m–o)), (q) 40 μm (applicable to (e–h) and (n–q)).