Abstract
(1) Background: The botulinum toxin A (BoNT-A) heavy chain (HC) can stimulate the growth of primary motor neurites. (2) Methods: A recombinant BoNT/A HC was injected locally plus interval intrathecal catheter of BoNT/A HC to rats with ipsilateral semi-dissociated lumbar spinal cord injuries (SCIs). First, 2D gel with a silver nitrate stain was applied to detect the general pattern of protein expression. Growth associated protein 43 (GAP-43) and superior cervical ganglion 10 (SCG10) were chosen to represent the altered proteins, based on their molecular weight and pI, and were used to further detect their expression. Meanwhile, the neuronal processes were measured. The measurements of thermal hyperalgesia and grasp power at the ipsilateral hindlimb were used to evaluate spinal sensory and motor function, respectively. (3) Results: The local injection of BoNT/A HC followed by its intrathecal catheter intervally altered the spinal protein expression pattern after an SCI; protein expression was similar to normal levels or displayed a remarkable increase. The changes in the expression and distribution of phosphorylated growth associated protein 43(p-GAP 43) and superior cervical ganglion 10 (SCG 10) indicated that the administration of BoNT/A HC to the SCI significantly amplified the expression of p-GAP43 and SCG10 (p < 0.05). Meanwhile, the positive immunofluorescent staining for both p-GAP43 and SCG10 was mainly present near the rostral aspect of the injury, both in the cytoplasm and the neuronal processes. Moreover, the outgrowth of neurites was stimulated by the BoNT/A HC treatment; this was evident from the increase in neurite length, number of branches and the percentage of cells with neuronal processes. The results from the spinal function tests suggested that the BoNT/A HC did not affect sensation, but had a large role in improving the ipsilateral hindlimb grasp power (p < 0.05). (4) Conclusions: The local injection with the intermittent intrathecal administration of BoNT/A heavy chain to rats with SCI increased the local expression of GAP-43 and SCG 10, which might be affiliated with the regeneration of neuronal processes surrounding the injury, and might also be favorable to the relief of spinal motor dysfunction.
Highlights
A spinal cord injury (SCI) is a devastating condition characterized by a sudden loss of spinal functions distal to the level of trauma, including sensory, motor, and autonomic function
Increased the local expression of Growth associated protein 43 (GAP-43) and superior cervical ganglion 10 (SCG 10), which might be affiliated with the regeneration of neuronal processes surrounding the injury, and might be favorable to the relief of spinal motor dysfunction
The results indicated that the paw withdrawal latency (PWTL) was prolonged after an SCI, with or without the application of the paw withdrawal latency (PWTL) was prolonged after an SCI, with or without the application of heavy chain (HC),HC, andand there was nonosignificant betweenthe theSCI
Summary
A spinal cord injury (SCI) is a devastating condition characterized by a sudden loss of spinal functions distal to the level of trauma, including sensory, motor, and autonomic function. The toxicity of BoNT/A is due to its selective binding to the membranous receptor located on the presynaptic membrane of the motor endplate This leads to the cleavage of the synaptosomal-associated protein 25 kDa (or SNAP-25) which blocks the release of the neurotransmitter acetylcholine contained in the vesicles [15,16]. The increased phosphorylation of Akt and ERK1/2 (growth- and survival-related intracellular signal proteins) was paralleled with neuritogenesis when adding BoNT/A heavy chain into neuro-2a cell cultures (data published in Chinese). It is reasonably presumed that BoNT/A heavy chain exerted its biological roles by modulating many intracellular signals and proteins expression, some of which may be involved in neural growth and regeneration; others are possibly related to growth inhibition.
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