Effect of FK506 administration after obturator nerve injury: a functional and ultrastructural study.

The frequency of obturator nerve damage due to pelvic diseases, fractures or gynecologic procedures is uncertain. In the present study, we investigated the effect of FK506, a potent macrolide antibiotic and immunosuppresant, on obturator nerve recovery at morphological and functional levels. Forty female Wistar rats were randomly divided into four groups (control, sham, FK506-treated, vehicle-treated). In half of animals (FK506-treated and vehicle-treated) an obturator nerve crush (30 seconds clamp) was created. In FK506-treated group FK506 administration (1 mg/kg/day, subcutaneously) was performed on each postoperative day. All the rats were functionally evaluated by pinch and adduction tests preoperatively and postoperatively at one, two, three and four weeks after nerve injury. On the 28th postoperative day obturator nerve samples were collected and analyzed qualitatively by light and electron microscopy. FK506 treatment resulted in dramatic improvement in nerve function and in the ultrastructure of nerve fibers suggesting its therapeutic potential in traumatic obturator nerve injury.

Morphological and ultrastructural analysis of the watershed zones after stripping of the vasa nervorum.

Peripheral nerve trunks are well-vascularized structures where a well-developed collateral system may compensate for local vascular damage. Vasculitis in nerve has a predilection for epineurial vessels and causes to the peripheral neuropathy, which is a major clinical feature of primary and secondary systemic vasculitides. In the present study, the goal was to simulate the vasculitic neuropathy in rat sciatic nerve and to investigate the watershed zones after stripping of the epineural vessels of the sciatic nerve. Sciatic function index values, light and electron microscopic evaluations of the experimental sciatic nerve suggested that the sciatic nerve was normal except for some watershed zones located in the peripheral part of the nerve. Although there is abundant collateral circulation in the peripheral nerve, distribution of the vessels of the watershed zones as observed in the present study should be elucidated by further studies.

Effect of intrathecal FK506 administration on intraorbital optic nerve crush: an ultrastructural study.

OBJECTIVE: Trauma to the optic nerve caused by fractures of the midface and (or) skull base has been simulated by an optic nerve crush injury model. Because the intraorbital segment of the optic nerve is surrounded by subarachnoidal cerebrospinal fluid and dura mater, we aimed to study the influence of intrathecal tacrolimus (FK506) administration after optic nerve crush injury and to determine its role in optic nerve protection or sparing after injury. STUDY DESIGN: Experimental study. PARTICIPANTS: All optic nerves of the animals were included in the study. METHODS: A total of 48 female Wistar rats were randomly divided into 4 groups (control, sham operated, FK506 treated, and vehicle treated). In vehicle- and FK506-treated groups, intrathecal catheter implantation and crush injury to the intraorbital part of the optic nerve were performed and then the animals were treated intrathecally. The optic nerve samples were harvested on the 30th postoperative day. Optic nerve appearances were analyzed qualitatively. RESULTS: Light and electron microscopic evaluations revealed that numerous damaged myelin residues were present in the vehicle-treated group, whereas fibres of the optic nerve showed a well-shaped appearance in the FK506-treated group. CONCLUSION: We propose that such an intrathecal administration route and small-dose regimen should be used to obtain lesser immunosuppression and neurotoxicity and higher protection or sparing after injury.

A standardized method to create optic nerve crush: Yasargil aneurysm clip.

It is often difficult to compare results obtained by different investigators on nerve compression injuries, owing to differences in method of pressure application and noncomparable pressure levels. In the present study, we described a new method to crush the optic nerve by using a specially designed and commercially available device. We think that standardization of the compression methods is necessary to compare interlaboratory results.

Effect of severe crush injury on axonal regeneration: a functional and ultrastructural study.

In the present study, we performed sciatic nerve compression for 30, 45, and 60 minutes by the Yasargil aneurysm clip and observed recovery on postoperative days 14, 28, and 42. We observed that as compress time increases, functional recovery and morphological regeneration of crushed sciatic nerve needs longer time. Additionally, we showed which cells are durable in nerve regeneration after crush injury. Nerve regeneration or recovery depends on trauma durations in which a longer recovery time is needed after longtime pressure. Although Schwann cells are found to be resistant and this might be for the cleanup of debris and remyelinization at mild injury, macrophage infiltration is necessary for the cleanup of damaged fragments of cells and fibers. The result indicates that a strong relationship exists between nerve damage and subsequent recovery. This phenomenon may depend on crush severity that is associated with mechanic pressure and inadequate logistic supports such as malnutrition and hypoxia. Additionally, we found that the Yasargil aneurysm clip is an appropriate device to perform a standard experimental severe crush injury model.