Dexamethasone prevents vascular damage in early-stage non-freezing cold injury of the sciatic nerve

Recent Findings on the Effects of Pharmacological Agents on the Nerve Regeneration after Peripheral Nerve Injury

Peripheral nerve injuries (PNIs) are accompanied with neuropathic pain and functional disability. Despite improvements in surgical repair techniques in recent years, the functional recovery is yet unsatisfied. Indeed a successful nerve repair depends not only on the surgical strategy but also on the cellular and molecular mechanisms involved in traumatic nerve injury. In contrast to all strategies suggested for nerve repair, pharmacotherapy is a cheap, accessible and non-invasive treatment that can be used immediately after nerve injury. This study aimed to review the effects of some pharmacological agents on the nerve regeneration after traumatic PNI evaluated by functional, histological and electrophysiological assessments. In addition, some cellular and molecular mechanisms responsible for their therapeutic actions, restricted to neural tissue, are suggested. These findings can not only help to find better strategies for peripheral nerve repair, but also to identify the neuropathic effects of various medications and their mechanisms of action.

Evaluation of dexamethasone treated mesenchymal stem cells for recovery in neurotmesis model of peripheral nerve injury

OBJECTIVE

Peripheral nerve injuries comprise significant portion of the nervous system injuries. Although peripheral nerves show some capacity of regeneration after injury, the extent of regeneration is not remarkable. The present study aimes to evaluate the regeneration of transected sciatic nerve by a therapeutic value of dexamethasone (DEX) associated with cell therapy (Cell) and biodegradable membrane (Mem) in rat.

METHODS

Male Wistar rats (n = 42, 180-200g) were randomly divided into control (Ctrl), Membrane+ Cell, Mem, DEX, DEX+ Cell, DEX+ Mem and DEX+ Cell+ Mem groups. Functional recovery was evaluated at 2, 4, 6, 8 and 12 weeks after surgery using sciatic functional index (SFI), withdrawal reflex latency (WRL) test, electrophysiological and histological analyses.

RESULTS

The rats in the DEX+ Cell+ Mem-treated group showed a significant improvement in SFI, WRL and electrophysiological findings during the 2nd to 12th weeks after surgery. In addition, histomorphological findings showed a significant improvement in the DEX+ Cell+ Memtreated group, at 12 weeks after surgery.

DISCUSSION

Taken together, use of DEX associated with cell and biodegradable membrane could improve functional and histomorphological properties of the sciatic nerve after injury.

Boric acid reduces axonal and myelin damage in experimental sciatic nerve injury

The aim of this study was to investigate the effects of boric acid in experimental acute sciatic nerve injury. Twenty-eight adult male rats were randomly divided into four equal groups (n = 7): control (C), boric acid (BA), sciatic nerve injury (I), and sciatic nerve injury + boric acid treatment (BAI). Sciatic nerve injury was generated using a Yasargil aneurysm clip in the groups I and BAI. Boric acid was given four times at 100 mg/kg to rats in the groups BA and BAI after injury (by gavage at 0, 24, 48 and 72 hours) but no injury was made in the group BA. In vivo electrophysiological tests were performed at the end of the day 4 and sciatic nerve tissue samples were taken for histopathological examination. The amplitude of compound action potential, the nerve conduction velocity and the number of axons were significantly lower and the myelin structure was found to be broken in group I compared with those in groups C and BA. However, the amplitude of the compound action potential, the nerve conduction velocity and the number of axons were significantly greater in group BAI than in group I. Moreover, myelin injury was significantly milder and the intensity of nuclear factor kappa B immunostaining was significantly weaker in group BAI than in group I. The results of this study show that administration of boric acid at 100 mg/kg after sciatic nerve injury in rats markedly reduces myelin and axonal injury and improves the electrophysiological function of injured sciatic nerve possibly through alleviating oxidative stress reactions.