Functional assessment of the rat sciatic nerve following intraoperative expansion: the effect of recovery duration on behavioural, neurophysiological, and morphological measures

The effects of exercise and conjugated linoleic acid intake on IGF-1 and pro-inflammatory cytokines in atrophied skeletal muscle of rats

BACKGROUND

Conjugated linoleic acid (CLA) can be proposed as an effective nutrient for skeletal muscle atrophy. However, the research related to this is still insufficient. This study was carried out to analyze the mRNA expression of IGF-1 and cytokines in atrophied skeletal muscle of rats.

METHODS

Forty-two rats were randomly divided into seven groups, each group containing six rats. Sham-Pre and USN-Pre groups underwent a sham operation and a unilateral sciatic nerve (USN) cut, and were sacrificed 1 week later. Other groups had 4 weeks of treatment exercise and CLA intake, and then their blood, liver, and skeletal muscles were sampled after sacrifice.

RESULTS

Among the treatment groups, the group treated with both exercise and CLA (USN-EC) showed the lowest body weight. Groups with the sciatic nerve cut showed significantly (p < 0.05) lower muscle weight than groups with the sham operation. However, exercise and CLA intake had no effect on muscle weight. Regarding IGF-1 mRNA, the USN-EC group showed significantly higher expressions in the red muscle of the gastrocnemius and liver than the Sham-Pre and USN-CLA groups. Regarding TNF-α pro-inflammatory cytokine, there was no particular trend; however, the expression of IL-1β mRNA increased in the white muscle of the gastrocnemius muscle and tibialis anterior muscle after sciatic nerve cut, but showed a decrease with exercise and CLA treatment. Particularly in the gastrocnemius white muscle, the group treated with both exercise and CLA showed a significant decrease as compared to groups without treatment after sciatic nerve cut so that positive effects can be expected.

CONCLUSION

It is thought that combining treadmill training with CLA partially influences pro-inflammatory cytokines, so that this can act positively on improving skeletal muscle atrophy caused by sciatic nerve cut.

Assessment of nerve regeneration across nerve allografts treated with tacrolimus

Although regeneration of nerve allotransplant is a major concern in the clinic, there have been few papers quantitatively assessing functional recovery of animals' nerve allografts in the long term. In this study, functional recovery, histopathological study, and immunohistochemistry changes of rat nerve allograft with FK506 were investigated up to 12 weeks without slaughtering. C57 and SD rats were used for transplantation. The donor's nerve was sliced and transplanted into the recipient. The sciatic nerve was epineurally sutured with 10-0 nylon. In total, 30 models of transplantation were performed and divided into 3 groups that were either treated with FK506 or not. Functional recovery of the grafted nerve was serially assessed by the pin click test, walking track analysis and electrophysiological evaluations. A histopathological study and immunohistochemistry study were done in the all of the models. Nerve allografts treated with FK506 have no immune rejection through 12 weeks. Sensibility had similarly improved in both isografts and allografts. There has been no difference in each graft. Walk track analysis demonstrates significant recovery of motor function of the nerve graft. No histological results of difference were found up to 12 weeks in each graft. In the rodent nerve graft model, FK506 prevented nerve allograft rejection across a major histocompatibility barrier. Sensory recovery seems to be superior to motor function. Nerve isograft and allograft treated with FK506 have no significant difference in function recovery, histopathological result, and immunohistochemistry changes.

Promotion of nerve regeneration in peripheral nerve by short-course FK506 after end-to-side neurorrhaphy

BACKGROUND/AIMS

To discuss the feasibility of peripheral nerve injury treated by end-to-side neurorrhaphy in clinic and to evaluate the effect of short-course FK506 on promoting nerve regeneration after end-to-side neurorrhaphy.

METHODS

Thirty adult male Sprague Dawley rats were randomly divided into 3 groups: Group A, 10 rats received end-to-end anastomosis; Group B, 10 rats received end-to-side neurorrhaphy; Group C, 10 rats received the same operation as Group B. After operation, rats in Groups B and C received muscle injection with saline water (1 mg/kg x d(-1)) and FK506 (1 mg/kg x d(-1)), respectively, both for 4 wk. Histological and morphological examinations were performed 12 wk after the operation. In the 2nd, 4th, 6th, 8th, and 12th wk after operation, function recovery analysis was performed.

RESULTS

The results of histological and immunochemistry study (the total number of Schwann cells and the axon numbers at the distal stump of the peroneal nerve, wet weight of extensor digitorum longus muscle) suggested that there were significant differences between Group B (saline water group) and Group C (FK506 group) (P < 0.05), also between Group A (end-to-end group) and Group C (P < 0.05). There were statistically significant differences in function recovery (peroneal functional index and sciatic functional index) between Groups B and C (P < 0.05) and also between Groups A and C (P < 0.05).

CONCLUSION

End-to-side repair combined with FK506 has a potential for application in selected cases of peripheral nerve injury in clinic.

Effects of antineoplastic agents on the peripheral nerves under a surgical tissue expansion procedure: An experimental study

BACKGROUND

Elongation of peripheral nerve by the use of a tissue expander is helpful to repair nerve defects. This study was designed to investigate the effects of some antineoplastic agents on the peripheral nerves under a surgical tissue expansion procedure.

MATERIALS AND METHODS

Twenty-five Wistar rats were used in this study. Following the exposition of the sciatic nerve and placement of two 10/0-nylon sutures in the epineurium 20 mm apart, a tissue expander was then placed under it. Inflation of the expander was immediately accomplished by the separate percutaneous injections of 6, 6, and 8 ml for every 3 min under general anesthesia. The expander was fully deflated at the end of each 3 min The distance between two sutures was measured 1 h later to measure the rate of elongation. Rats were randomly divided into five groups (according to the administered drugs), each consisting of five rats (10 sciatic nerves). Normal saline (1 ml) in the control group (group I), cyclophosphamide (15 mg/kg) in the group II, cisplatinum (3 microg/kg) in the group III, mitomycin-C (0.5 mg/kg) in the group IV and 5-fluorouracil (10 mg/kg) in the group V were injected intravenously. Intravenous injections of drugs were performed via the tail vein 30 min before expansion, 48 and 96 h after removal of expander. The incision was reopened on the third and seventh postoperative days, and five sciatic nerves of each group were exposed and then the pinching test was performed to measure regeneration distance. Electroneurographic changes were recorded. The expanded portion of the sciatic nerve between two sutures was harvested for histological evaluation.

RESULTS

There is no significant difference between the elongation rates of all groups (P < 0.05). Histologic evaluation showed that inflammatory changes, vacuolization, intraneural edema, demyelination, axonal changes in the control group, the cisplatinum group, and the mitomycin-C group. These changes were significantly decreased in the cyclophosphamide group and the 5-fluorouracil group. In the cyclophosphamide group and the 5-fluorouracil group, the amplitude of compound action potential (CAP) values were significantly higher and the latency was significantly shorter (P > 0.05).

CONCLUSION

We believed that cyclophosphamide and 5-fluorouracil may be helpful in tissue expansion of peripheral nerves, by decreasing the effects of the ischemia-reperfusion injury on the expanded peripheral nerves.

Maximum intraoperative elongation of the rat sciatic nerve with tissue expander: Functional, neurophysiological, and histological assessment

The purpose of this study was to assess the maximum rapid intraoperative elongation of the rat sciatic nerve with the use of tissue expander, and its possible functional recovery. One hundred and eight rats were divided into five groups, and their right sciatic nerves were expanded with a 10-cc, 12-cc, 14-cc, 16-cc, and 18-cc expander, respectively, for 1 h. The functional recovery of the nerve was assessed at intervals up to 3 months, using the sciatic function index (SFI), neurophysiological indices, and histology. The maximum intraoperative elongation was observed in group IV (16-cc volume of tissue expander), at about 23.83%. SFI decreased between the first and seventh postoperative days, but gradually recovered, reaching preoperative values in all groups according to the formulas of De Medinaceli et al. (Exp. Neurol. 77:634-643, 1982) and Bain et al. (Plast. Reconstr. Surg. 83:129-136, 1989). Latency and motor conduction velocity demonstrated deterioration after expansion, which peaked after surgery. Recovery was gradually completed by the end of the experiment. The histological findings indicated minor aberrations immediately after expansion and maximal demyelination with axonal disruption on day 15. The reparative process started by day 30 and continued until day 90, when almost no histological changes were observed. In conclusion, intraoperative nerve expansion successfully elongates the rat sciatic nerve up to 23.83%. But it causes functional and morphological abnormalities, which are of moderate to severe degree, are of short duration, and are reversible. Intraoperative nerve expansion might be a valuable solution in the treatment of short nerve gaps, but its clinical application still needs to be evaluated.