Research Paper Volume 8, Issue 9 pp 2062—2080

Age-associated repression of type 1 inositol 1, 4, 5-triphosphate receptor impairs muscle regeneration

Figure 6. Restoration of aged muscle by ERK inhibition. (A) Old primary myoblasts were induced to differentiate in the presence or absence of U0126 (5 μM) for 2 days. Myh3 mRNA levels was measured relative to 36b4 using qRT-PCR. (B) Scheme of the in vivo experimental procedure. Mouse TA muscles were injected with 50 μl of 20 μM CTX using an insulin syringe at day 0. Three days after CTX injury, U0126 was injected intraperitoneally (10 mg/kg) daily. Control young and aged mice were injected with carrier solution for 14 days. (C) qRT-PCR analysis of mRNA expression of Itpr1, myogenesis regulatory genes (Myod1, Myog, Myh3) and muscle hypertrophic regulatory genes (Igf-1, Igf-1e, Mgf), relative to 36b4, in TA muscles of young, U0126- and carrier- injected aged mice. n = 3 for each group. (D) Representative immunohistochemistry images of Laminin (green) and DAPI (blue) staining of TA muscle fibers from U0126- and carrier- injected mice 14 days after CTX injury. Cross-sectional areas of muscle fibers were measured using NIS-Elements Microscope Imaging software (Nikon) and fiber size distributions are presented as means ± S.D (n = 3 for each group). (E) Schematic illustration of our model