Measuring temporal expression, systematic response, and post-mortem stability to assess potential markers for estimating wound age: an example of Fosl1 in contused skeletal muscle

Abstract

To assess whether Fosl1 is a suitable parameter for wound age estimation, a total of 126 male Sprague–Dawley rats were divided into control (n = 6 per group), contusion (including 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, and 48 h post-severe injury, and 4 or 8 h post-moderate or -mild injury subgroups), and post-mortem (including 6, 12, 18, and 24 h subgroups) groups (n = 6 per subgroup). A contusion was produced in the right limb of the rats using the drop-ball technique (under intraperitoneal chloral hydrate anaesthesia), and the animals were sacrificed using a lethal dose of pentobarbital. The expression of Fosl1 mRNA and protein was determined in the contused and contralateral uninjured muscle and post-mortem specimens of musculi quadriceps femoris using real-time PCR and western blotting, respectively. Compared with the control group, the expression of Fosl1 mRNA was increased in several contused and contralateral uninjured muscles, and decreased in post-mortem groups (P<0.05). The expression of Fosl1 protein was increased in the 4, 8, 32, 36, 40, 44, and 48 h contusion subgroups (P<0.05), but there was no significant change in the contralateral uninjured muscles and post-mortem specimens. The results indicated that Fosl1 protein was more specific and stable than Fosl1 mRNA, which suggests that the temporal expression, systematic response, and post-mortem stability should be comprehensively analysed when exploring other markers for use in wound age estimation in the future.