Abstract
In laboratory studies, counting the spinal motoneurons that survived axonal injury is a major method to estimate the severity and regenerative capacity of the injured motoneurons after the axonal injury and rehabilitation surgery. However, the typical motoneuron marker, the choline acetyltransferase (ChAT), could not be detected in the injured motoneurons within the first 3–4 weeks postinjury. It is necessary to explore the useful and reliable specific phenotypic markers to assess the fate of injured motoneurons in axonal injury. Here, we used the fluorogold to retrograde trace the injured motoneurons in the spinal cord and studied the expression patterns of the alpha-motoneuron marker, the neuronal nuclei DNA-binding protein (NeuN) and the peripheral nerve injury marker, the activating transcriptional factor (ATF-3), and the oxidative stress marker, the neuronal nitric oxide synthase (nNOS) within the first 4 weeks of the root avulsion of the right brachial plexus (BPRA) in the adult male Sprague-Dawley rats. Our results showed that ATF-3 was rapidly induced and sustained to express only in the nuclei of the fluorogold-labeled injured motoneurons but none in the unaffected motoneurons from the 24 h of the injury; meanwhile, the NeuN almost disappeared in the avulsion-affected motoneurons within the first 4 weeks. The nNOS was not detected in the motoneurons until the second week of the injury. On the basis of the present data, we suggest that ATF-3 labels avulsion-injured motoneurons while NeuN and nNOS are poor markers within the first 4 weeks of BPRA.
Highlights
In clinic, the brachial plexus root avulsion (BPRA) is the most serious axonal injury which causes permanent paralysis of the ipsilateral limb muscles
On the basis of the present data, we suggest that ATF-3 labels avulsion-injured motoneurons while neuronal nuclei DNAbinding protein (NeuN) and neuronal nitric oxide synthase (nNOS) are poor markers within the first 4 weeks of BPRA
Since the motoneurons innervating upper limb muscles reside in the lateral motor column (LMC) at the cervical spinal levels of the mammalian spinal cord (Dasen et al 2005; Goetz et al 2015), the number of the motoneurons stained by the traditional neutral red in the LMC of the C5-T1 spinal segments was commonly used to assess the survival and regenerative capacity of the affected motoneurons in BPRA (Oppenheim et al 1995)
Summary
The brachial plexus root avulsion (BPRA) is the most serious axonal injury which causes permanent paralysis of the ipsilateral limb muscles. In the studies of the animal model of BPRA, previous studies have proven that the unilateral avulsion of both ventral and dorsal roots of the brachial plexus only affects the ipsilateral ventral horn and caused the death. Many previous studies have proven that axonal injury results in the absences of ChAT expression in the affected motoneurons within the first 3–4 weeks postinjury (Rende et al 1995; Hoang et al 2003; Zhou et al 2008; Eggers et al 2010; Peddie and Keast 2011)
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