Nimodipine and acceleration of functional recovery of the facial nerve after crush injury

Effect of Local Administration of Verapamil Combined with Chitosan Based Hybrid Nanofiber Conduit on Transected Sciatic Nerve in Rat

Objective:

To assess the effect of locally administered verapamil on transected peripheral nerve regeneration and functional recovery.

Methods:

Sixty male healthy white Wistar rats were divided into four experimental groups (n=15), randomly: In transected group (TC), left sciatic nerve was transected and stumps were fixed in the adjacent muscle. In treatment group defect was bridged using chitosan tube (CHIT/Verapamil) filled with 10 µL verapamil (100ng/mL). In chitosan conduit group (CHIT), the tube was filled with phosphate-buffered saline alone. In sham-operated group (SHAM), sciatic nerve was exposed and manipulated. The repair trend was examined based on behavioral and performance tests as well as the variations of the gastrocnemius muscle, morphometric indices, and immunohistochemical indices.

Results:

Sciatic nerve functional study, muscle mass and morphometric indices confirmed faster recovery of regenerated axons in CHIT/Verapamil than CHIT group (P = 0.001). When loaded in a chitosan tube verapamil accelerated and improved functional recovery and morphometric indices of sciatic nerve. Immunohistochemical analysis revealed the S-100 protein was vastly present in the transverse nerve sections and the myelin sheath. In the treatment group (chit/verapamil), the immunohistochemical susceptibility of the axons being repaired and the axons in the myelin sheath to S-100 protein was higher than the other groups.

Conclusion:

The present study demonstrated that a single local application of verapamil could accelerate functional recovery after transection of sciatic nerve.

Protective effects of intraperitoneal administration of nimodipine on ischemia-reperfusion injury in ovaries: Histological and biochemical assessments in a rat model

PURPOSE

Ovarian torsion must be diagnosed and treated as much early as possible. The aim of the present study was to investigate effects of intraperitoneal administration of nimodipine on ischemia-reperfusion injury in ovaries.

METHODS

Thirty healthy male Wistar rats weighing approximately 250g were randomized into six experimental groups (n=5): Group Sham: The rats underwent only laparotomy. Group I: A 3-h ischemia only. Group I/R: A 3-h ischemia and a 3-h reperfusion. Group I/Nimodipine: A 3-h ischemia only and 1mg/kg intraperitoneal administration of nimodipine 2.5h after induction of ischemia. Group I/R/Nimodipine: A 3-h ischemia, a 3-h reperfusion and 1mg/kg intraperitoneal administration of nimodipine 2.5h after induction of ischemia.

RESULTS

Nimodipine treated animals showed significantly ameliorated development of ischemia and reperfusion tissue injury compared to those of other groups (P<0.05). The significant higher values of SOD, tGSH, GPO, GSHRd and GST were observed in I/R/Nimodipine animals compared to those of other groups (P<0.05). The damage indicators (NOS, MDA, MPO and DNA damage level) were significantly lower in I/R/Nimodipine animal compared to those of other groups (P<0.05).

CONCLUSIONS

Intraperitoneal administration of nimodipine could be helpful in minimizing ischemia-reperfusion injury in ovarian tissue exposed to ischemia.

Prophylactic nimodipine treatment and improvement in hearing outcome after vestibular schwannoma surgery: a combined analysis of a randomized, multicenter, Phase III trial and its pilot study

OBJECTIVE In clinical routines, neuroprotective strategies in neurosurgical interventions are still missing. A pilot study (n = 30) and an analogously performed Phase III trial (n = 112) pointed to a beneficial effect of prophylactic nimodipine and hydroxyethyl starch (HES) in vestibular schwannoma (VS) surgery. Considering the small sample size, the data from both studies were pooled. METHODS The patients in both investigator-initiated studies were assigned to 2 groups. The treatment group (n = 70) received parenteral nimodipine (1-2 mg/hour) and HES (hematocrit 30%-35%) from the day before surgery until the 7th postoperative day. The control group (n = 72) was not treated prophylactically. Facial and cochlear nerve functions were documented preoperatively, during the inpatient care, and 1 year after surgery. RESULTS Pooled raw data were analyzed retrospectively. Intent-to-treat analysis revealed a significantly lower risk for hearing loss (Class D) 12 months after surgery in the treatment group compared with the control group (OR 0.46, 95% CI 0.22-0.97; p = 0.04). After exclusion of patients with preoperative Class D hearing, this effect was more pronounced (OR 0.38, 95% CI 0.17-0.83; p = 0.016). Logistic regression analysis adjusted for tumor size showed a 4 times lower risk for hearing loss in the treatment group compared with the control group (OR 0.25, 95% CI 0.09-0.63; p = 0.003). Facial nerve function was not significantly improved with treatment. Apart from dose-dependent hypotension (p < 0.001), the study medication was well tolerated. CONCLUSIONS Prophylactic nimodipine is safe and may be recommended in VS surgery to preserve hearing. Prophylactic neuroprotective treatment in surgeries in which nerves are at risk seems to be a novel and promising concept. Clinical trial registration no.: DRKS 00000328 ( https://drks-neu.uniklinik-freiburg.de/drks_web/ ).

Nimodipine-mediated re-myelination after facial nerve crush injury in rats

This study aimed to investigate the mechanism of nimodipine-mediated neural repair after facial nerve crush injury in rats. Adult Sprague-Dawley rats were divided into three groups: healthy controls, surgery alone, and surgery plus nimodipine. A facial nerve crush injury model was constructed. Immediately after surgery, the rats in the surgery plus nimodipine group were administered nimodipine, 6 mg/kg/day, for a variable numbers of days. The animals underwent electromyography (EMG) before surgery and at 3, 10, or 20 days after surgery. After sacrifice, nerve samples were stained with hematoxylin and eosin (H&E) and luxol fast blue. The EMG at 20 days revealed an apparent recovery of eletroconductivity, with the surgery plus nimodipine group having a higher amplitude and shorter latency time than the surgery only group. H&E staining showed that at 20 days, the rats treated with nimodipine had an obvious recovery of myelination and reduction in the number of infiltrating cells, suggesting less inflammation, compared with the rats in the surgery only group. Luxol fast blue staining was relatively even in the surgery plus nimodipine group, indicating a protective effect against injury-induced demyelination. Staining for S100 calcium-binding protein B (S-100β) was not evident in the surgery alone group, but was evident in the surgery plus nimodipine group, indicating that nimodipine reversed the damage of the crush injury. After a facial nerve crush injury, treatment with nimodipine for 20 days reduced the nerve injury by mediating remyelination by Schwann cells. The protective effect of nimodipine may include a reduction of inflammation and an increase in calcium-binding S-100β protein.

Nimodipine enhances neurite outgrowth in dopaminergic brain slice co-cultures

Calcium ions (Ca(2+)) play important roles in neuroplasticity and the regeneration of nerves. Intracellular Ca(2+) concentrations are regulated by Ca(2+) channels, among them L-type voltage-gated Ca(2+) channels, which are inhibited by dihydropyridines like nimodipine. The purpose of this study was to investigate the effect of nimodipine on neurite growth during development and regeneration. As an appropriate model to study neurite growth, we chose organotypic brain slice co-cultures of the mesocortical dopaminergic projection system, consisting of the ventral tegmental area/substantia nigra and the prefrontal cortex from neonatal rat brains. Quantification of the density of the newly built neurites in the border region (region between the two cultivated slices) of the co-cultures revealed a growth promoting effect of nimodipine at concentrations of 0.1μM and 1μM that was even more pronounced than the effect of the growth factor NGF. This beneficial effect was absent when 10μM nimodipine were applied. Toxicological tests revealed that the application of nimodipine at this higher concentration slightly induced caspase 3 activation in the cortical part of the co-cultures, but did neither affect the amount of lactate dehydrogenase release or propidium iodide uptake nor the ratio of bax/bcl-2. Furthermore, the expression levels of different genes were quantified after nimodipine treatment. The expression of Ca(2+) binding proteins, immediate early genes, glial fibrillary acidic protein, and myelin components did not change significantly after treatment, indicating that the regulation of their expression is not primarily involved in the observed nimodipine mediated neurite growth. In summary, this study revealed for the first time a neurite growth promoting effect of nimodipine in the mesocortical dopaminergic projection system that is highly dependent on the applied concentrations.

Improvement of peripheral nerve defects using a silicone conduit filled with hepatocyte growth factor

OBJECTIVE

To assess local effects of hepatocyte growth factor (HGF) on peripheral nerve repair in a rat sciatic nerve transection model.

STUDY DESIGN

Sixty male, healthy, white Wistar rats were randomized into 4 experimental groups: In the sham-operated group, sciatic nerve was exposed and manipulated. In the transected control group, the left sciatic nerve was transected. In the silicone graft group (SIL), a 10-mm defect was made and bridged using a silicone tube. The graft was filled with phosphate-buffered saline in the SIL group and with HGF in the SIL/HGF group.

RESULTS

Behavioral testing, sciatic nerve functional study, gastrocnemius muscle mass measurement, and morphometric indices found earlier regeneration of axons in the SIL/HGF than in the SIL group (P < .05). Immunohistochemical study clearly found more positive location of reactions to S-100 in the SIL/HGF group than in the SIL group.

CONCLUSIONS

HGF may have clinical implications for the surgical management of patients after facial nerve transection.

Small molecule inhibitors in the treatment of cerebral ischemia

INTRODUCTION

Stroke is the world's second leading cause of death. Although recombinant tissue plasminogen activator is an effective treatment for cerebral ischemia, its limitations and ischemic stroke's complex pathophysiology dictate an increased need for the development of new therapeutic interventions. Small molecule inhibitors (SMIs) have the potential to be used as novel therapeutic modalities for stroke, since many preclinical and clinical trials have established their neuroprotective capabilities.

AREAS COVERED

This paper provides a summary of the pathophysiology of stroke as well as clinical and preclinical evaluations of SMIs as therapeutic interventions for cerebral ischemia. Cerebral ischemia is broken down into four mechanisms in this article: thrombosis, ischemic insult, mitochondrial injury and immune response. Insight is provided into preclinical and current clinical assessments of SMIs targeting each mechanism as well as a summary of reported results.

EXPERT OPINION

Many studies demonstrated that pre- or post-treatment with certain SMIs significantly ameliorated adverse effects from stroke. Although some of these promising SMIs moved on to clinical trials, they generally failed, possibly due to the poor translation of preclinical to clinical experiments. Yet, there are many steps being taken to improve the quality of experimental research and translation to clinical trials.

Peripheral nerve regeneration following transection injury to rat sciatic nerve by local application of adrenocorticotropic hormone

The objective of this study was to assess local effect of adrenocorticotropic hormone (ACTH) on the functional recovery of the sciatic nerve in a transection model. Sixty male healthy white Wistar rats were randomized into four experimental groups of 15 animals each: In the sham-operated group (SHAM), the sciatic nerve was exposed and manipulated. In the transected group (TC), the left sciatic nerve was transected and the cut nerve ends were fixed in the adjacent muscle. In the silicone graft group (SIL) a 10-mm defect was made and bridged using a silicone tube. The graft was filled with phosphated-buffer saline alone. In the treatment group a silicone tube (SIL/ACTH) was filled with 10 μL ACTH (0.1 mg/mL). Each group was subdivided into three subgroups of five animals each and regenerated nerve fibres were studied at 4, 8 and 12 weeks post operation. Behavioral testing, functional, gastrocnemius muscle mass and morphometric indices showed earlier regeneration of axons in SIL/ACTH than in SIL group (p < 0.05). Immunohistochemistry clearly showed more positive location of reactions to S-100 in SIL/ACTH than in SIL group. ACTH improved functional recovery and morphometric indices of sciatic nerve. This finding supports role of ACTH after peripheral nerve repair and may have clinical implications for the surgical management of patients after nerve transection.

A system for delivering mechanical stimulation and robot-assisted therapy to the rat whisker pad during facial nerve regeneration

Functional recovery is typically poor after facial nerve transection and surgical repair. In rats, whisking amplitude remains greatly diminished after facial nerve regeneration, but can recover more completely if the whiskers are periodically mechanically stimulated during recovery. Here we present a robotic "whisk assist" system for mechanically driving whisker movement after facial nerve injury. Movement patterns were either preprogrammed to reflect natural amplitudes and frequencies, or movements of the contralateral (healthy) side of the face were detected and used to control real-time mirror-like motion on the denervated side. In a pilot study, 20 rats were divided into nine groups and administered one of eight different whisk assist driving patterns (or control) for 5-20 minutes, five days per week, across eight weeks of recovery after unilateral facial nerve cut and suture repair. All rats tolerated the mechanical stimulation well. Seven of the eight treatment groups recovered average whisking amplitudes that exceeded controls, although small group sizes precluded statistical confirmation of group differences. The potential to substantially improve facial nerve recovery through mechanical stimulation has important clinical implications, and we have developed a system to control the pattern and dose of stimulation in the rat facial nerve model.

Nimodipine improves regional cerebral blood flow and suppresses inflammatory factors in the hippocampus of rats with vascular dementia

OBJECTIVE

To study the effect of nimodipine on hippocampal regional cerebral blood flow (rCBF) and proinflammatory cytokines in rats with experimental vascular dementia.

METHODS

Male Sprague Dawley rats were randomly divided into four groups (n = 15/group): sham operated controls (group A); focal cerebral ischaemia (group B); vascular dementia (group C); and vascular dementia treated with 20 mg/kg nimodipine daily (group D). The Morris water maze test evaluated learning and memory, and magnetic resonance perfusion-weighted imaging was used to measure rCBF. Hippocampal levels of nuclear factor-κB (NF-κB), tumour necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) were measured.

RESULTS

Compared with group C, rats in group D demonstrated significantly improved learning ability and significantly increased hippocampal rCBF. The levels of NF-κB, TNF-α and IL-1β were significantly lower in group D than in group C. Hippocampal nerve cell morphology was abnormal in group C but near normal in group D.

CONCLUSIONS

Nimodipine improved the symptoms of cognitive impairment, increased rCBF, reduced hippocampal cytokine levels and alleviated neuronal injury in the hippocampus of rats with experimental vascular dementia.