@2024 Afarand., IRAN

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ISSN: 2252-0805    The Horizon of Medical Sciences 2017;23(3):207-214

Background
Peripheral nerves are always subject to a wide range of factors [1].
Previous Studies
… [2-14]. There is no definitive drug for spinal cord injury and peripheral nerve system and the effect of the only existing drug (methylprednisolone) is unanimous although it is used in all emergency and acute cases [15].
Aim(s)
The aim of the present study was to investigate the effects of methylprednisolone on improvement of motor function and tissue changes following sciatic nerve disruption and repair by degrading scaffolding transplantation in rats.
Research type
This is an experimental study.
Research society, place and time
This study was conducted from September 2015 to September 2016 at the Neurosurgery Research Laboratory of the Faculty of Basic Sciences of Ferdowsi University of Mashhad. Experiments were performed on 50 adult male Wistar rats weighing 250-300 grams and approximately 3 months old.
Sampling method and number
Experiments were performed on 50 adult male Wistar rats weighing 250-300 grams and approximately 3 months old.
Used devices&materials
The animals were randomly divided into 5 groups of 10 as follows: 1) Negative control group (discontinuation of sciatic nerve) 2) Sham group (surgery without a nerve cut-off accompanied with a solvent) 3) Experimental group 1 (Sciatic nerve cut-off and scaffold transplantation with a dose of 1 mg/kg) 4) Experimental group 2 (sciatic nerve cut-off and scaffold transplant with 30 mg/kg dose) 5) Experimental group 3 (sciatic nerve cut-off and scaffold transplantation with drug solvent) Animals in experimental groups 1 and 2 received methylprednisolone (Alborz Pharmaceutical Company, Iran) with 1 and 30 mg/kg doses respectively for one week respectively [14, 16]. The negative control group did not receive the drug, and in the sham group, only surgery was performed without damage to the nerve and with solvent medication [17]. … [18-19]. The walking test was performed at weeks 1, 4, 8, and 12 after surgery, and in each test, three footprints were measured and the mean was recorded [20]. In order to assess the extent of 12 weeks postoperative recovery, the proportion of gastrocnemius muscle mass fracture to healthy gastrocnemius muscle was evaluated. Then, for each rats, gastrocnemius muscle mass was calculated by the following formula according to the weight ratio of the foot muscle which had been under operation to the healthy foot muscle was calculated using the following formula [21]: Weight of muscle of healthy foot/surgical foot muscle weight=muscle mass ratio At week 12 after operation, the Combined Muscle Activity Potential (CMAP) from gastrocnemius muscle was recorded with PicoScope software. Record was repeated three times, and amplitude and delay of combined muscle action potential (CMAP) were recorded for each rat. Also, the potential of combined muscle action (CMAP) was recorded from a healthy non-surgical healthy foot. All the data were entered into the computer to calculate the electrophysiological parameters. The distal part was removed from the affected sciatic nerve (left leg) in the treated and controlled groups and then the nerves were fixed in 4% paraformaldehyde. After the dewatering steps with ascending ethanol, the samples were molded and serial sections of the sample were prepared with ultramicrotomy. Then, the samples were stained with 1% toluidiblone color, followed by counting the axons, fiber diameter, and thickness of the myelin layer using Image J software. The sciatic nerve of the right foot was considered as the control sample. Statistical analysis: The statistical design of the study was completely randomized design. Data were expressed as mean. One-way ANOVA was used to analyze the data and to compare the mean of variables in the experimental groups, Tukey's post hoc test was used. All the statistical analysis and drawing of the charts were done using SPSS 16 software.
Findings by Text
Functional evaluation of the sciatic nerve in pathway walking test: before surgery, SFI levels were close to zero in all experimental groups. In the first week after nerve disruption due to complete loss of function of sciatic nerve, the SFI level in all groups was significantly lower than the sham group that is at the lowest level near -100. Four weeks after operation in methylprednisolone treated group with doses of one and 30 mg/kg increased to -62.92±3.5 and -56.07±2.7 respectively and in the experimental group, the scaffold with the drug solvent increased to -64.34±4.2 which was significant in comparison with the sham group. There was no change in sham group and control group in this week. In the eighth week after surgery, SFI level were -58.08±3.4, -51.87±3.1, and -61.85±2.8 respectively for methylprednisolone-treated groups with single does and 30 mg/kg and the experimental group received scaffold transplant with solvent medication that this difference was significant in comparison with the sham group. However, sham and negative control groups did not change. After 12 weeks, the levels of SFI in the treatment groups with methylprednisolone at dosages of 1 and 30 mg/kg were -52.06±3.3 and -46.18±4.1respectively, and in the experimental group, scaffold transplantation with receiving the solvent of the drug was increased to -54.63± 3.5, which was significant in comparison with the sham group. However, no changes were observed in sham and negative control groups. In comparison with methylprednisolone at doses of 1 and 30 mg/kg, the SFI value increased significantly in the methylprednisolone at dose of 30 mg/kg after the fourth week (Fig. 1). Gastrocnemius muscle mass: the mean weight ratio of muscle between the surgical foot and the healthy foot in the sham group after 12 weeks was about 0.95. However, in the negative control group, the weight ratio of the muscle showed a significant decrease and reached about 0.3. In groups treated with doses of one and 30 mg/kg methylprednisolone and in the experimental group, the scaffold transplant with the reception of the drug solvent showed significant increase compared to the control group. Also, with the increase of methylprednisolone, the weight loss of gastrocnemius muscle significantly decreased (Fig. 2). Electrophysiological evaluation: in all groups treated with methylprednisolone, as well as the experimental group of scaffold transplant, with the drug solvent, the amplitude of compounding operation was increased gradually. Also, the potential start delay was decreased. At the week 12 after lesion, the amplitude of combined muscle action potential and the delay in the negative control group, the experimental group of scaffold transplant with the solvent and the treatment groups with doses of 1 and 30 mg/kg methylprednisolone had a significant difference with the sham group. Also, in comparison with the treated groups with methylprednisolone, dose of 30 mg/kg compared to the dose of one mg/kg showed significantly higher potential amplitude and less delay (figures 3 and 4). Histomorphometry (stereology) Evaluation: Morphometric parameters such as mean number and diameter of fibers, mean number of axons and myelin sheath thickness in distal region in the treated groups with doses of 1 and 30 mg/kg methylprednisolone compared to the experimental scaffold bonding group with drug solvent was significantly higher, but it was lower than sham group (p<0.05, Table 1, and figure 1).
Main comparison to the similar studies
Many studies that examined the effects of anti-inflammatory and anti-oxidant agent on peripheral nerve system repair have shown positive effects in the reducing the amount of free radicals and other malignant factors. These agents also accelerate the improvement of peripheral nerve damage [16, 26]. … [27-32].
Suggestions
It is suggested that in future studies, the rate of motor activity recovery be evaluated up to week 16 or 20.
Limitations
Of the limitations of this study was the lack of study period.
Conclusions
Administration of methylprednisolone following the sciatic nerve cut and scaffold transplantation in rats increases the rate of motor function and tissue repair. Also, recovery of motor and tissue function at a high dose of methylprednisolone (30 mg/kg) is better than low dose (one mg/kg).
Acknowledgments
The Deputy of Research at Ferdowsi University of Mashhad is appreciated.
Conflict of interest
Non-declared
Ethical Permissions
All experiments were carried out at the Ferdowsi University of Mashhad Peripheral Nerves Repair Department according to the ethical guidelines for working with laboratory animals.
Funding Sources
The cost of this research has been provided by Mashhad Ferdowsi University.

TABLES and CHARTS

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