Possible antioxidant and neuroprotective mechanisms of FK506 in attenuating haloperidol-induced orofacial dyskinesia

Tardive dyskinesia is a serious motor side effect of chronic neuroleptic therapy. The pathophysiology of this disabling and commonly irreversible movement disorder is still obscure. It may be caused by a loss of dopaminergic cells, due to free radicals as a product of high synaptic dopamine levels. Chronic treatment with neuroleptics leads to the development of abnormal oral movements in rats called vacuous chewing movements. Vacuous chewing movements in rats are widely accepted as an animal model of tardive dyskinesia. Chronic haloperidol (1 mg/kg for 21 days) treatment significantly induced vacuous chewing movements and tongue protrusions in rats, and FK506 (Tacrolimus) [[3S-[3R*[E(1S*,3S*,4S*)],4S*,5R*,8S*,9E,12R*,14R*,15S*,16R*,18S*,19S*,26aR*]]-5,6,8,11,12,13,14,15,16,17,18,19,24,25,26,26a-hexadecahydro-5, 19-dihydroxy-3-[2-(4-hydroxy-3-methoxycyclohexyl)-1-methylethenyl]-14, 16-dimethoxy-4,10,12, 18-tetramethyl-8-(2-propenyl)-15, 19-epoxy-3H-pyrido[2,1-c][1,4] oxaazacyclotricosine-1,7,20, 21(4H,23H)-tetrone, monohydrate] dose dependently (0.5 and 1 mg/kg) reduced these haloperidol-induced movements. Biochemical analysis revealed that chronic haloperidol treatment significantly induced lipid peroxidation and decreased the levels of glutathione and of the antioxidant defense enzymes, superoxide dismutase and catalase, in the brains of rats. Co-administration of FK506 dose dependently (0.5 and 1 mg/kg) and significantly reduced the lipid peroxidation and restored the decreased glutathione levels induced by chronic haloperidol treatment. It also significantly reversed the haloperidol-induced decrease in brain superoxide dismutase and catalase levels. The major findings of the present study suggest that oxidative stress-induced neuronal death might play a significant role in neuroleptic-induced orofacial dyskinesia. In conclusion, FK506 could be a useful drug for the treatment of neuroleptic-induced orofacial dyskinesia.     

Comparative dose-dependence study of FK506 on transected mouse sciatic nerve repaired by allograft or xenograft

We evaluated the effects of FK506, at doses of 0.2, 2, and 5 mg/kg/day, on the response to nerve grafts implanted in outbred mice. A 6 mm long segment of the sciatic nerve was transected and repaired by autograft (the same segment resected), allograft (from another mouse), or xenograft (from a rat nerve). The regenerating nerves were harvested after 3 weeks and studied under light and electron microscope. Allografts of animals treated with the 5 mg/kg/day dose of FK506 appeared similar to those from autografts, demonstrating an equivalent number of myelinated fibers. In mice treated with the 2 mg/kg/day dose, regeneration was slightly hindered, as indicated by the reduced number of myelinated fibers. In contrast, in mice given a 0.2 mg/kg/day dose of FK506, allografts were not different from untreated allografts; both groups showed a marked rejection response with only few unmyelinated axons and no myelinated fibers. Xenografts showed a more severe rejection than allografts, with a marked inflammatory cell reaction throughout the graft. In contrast, in mice treated with the 5 mg/kg/day dose, xenografts exhibited a mild cell reaction and a greater number of regenerated myelinated fibers. In conclusion, effective axonal regeneration is achieved with FK506 administration at doses of 5 mg/kg/day through allografts and, partially, through xenografts.     

Effects of immunosuppression on regrowth of adult rat retinal ganglion cell axons into peripheral nerve allografts

Analysis of the effectiveness of allografts and immunosuppression in the repair of nerve defects in the adult peripheral nervous system (PNS) has a long experimental and clinical history. There is little information, however, on the use of allografts in peripheral nerve (PN) transplantation into the injured central nervous system (CNS). We assessed the ability of PN allografts (from Dark-Agouti rats) to support regeneration of adult rat retinal ganglion cell (RGC) axons in immunosuppressed host Lewis rats. PN allografts were sutured onto intraorbitally transected optic nerves. Three weeks after grafting, regenerating RGC axon numbers were determined using retrograde fluorescent labelling, and total axons within PN grafts were assessed using pan-neurofilament immunohistochemistry. In the absence of immunosuppression, PN allografts contained few axons and there were very few labelled RGC. These degenerate grafts contained many T cells and macrophages. Systemic (intraperitoneal) application of the immunosuppressants cyclosporin-A or FK506 reduced cellular infiltration into allografts and resulted in extensive axonal regrowth from surviving RGCs. The average number of RGCs regenerating axons into immunosuppressed allografts was not significantly different from that seen in PN autografts in rats sham-injected with saline. Many pan-neurofilament-positive axons, a proportion of which were myelinated, were seen in immunosuppressed allografts, particularly in proximal regions of the grafts toward the optic nerve-PN interface. This study demonstrates that PN allografts can support axonal regrowth in immunosuppressed adult hosts, and points to possible clinical use in CNS repair.     

Bone mass and mineral metabolism in liver transplant patients treated with FK506 or cyclosporine A

The purpose of this study was to compare the effects of Cyclosporine A (CyA) and FK506 on bone mass and mineral metabolism in liver transplantation (LT) patients. A prospective study was performed on 18 male patients who underwent LT treated with CyA, and 7 LT patients who received FK506. Bone mineral density (BMD) of the lumbar spine and proximal femur (DPX-L) was measured before and at 6, 12, and 24 months after transplantation. Moreover, intact parathyroid hormone (PTH) and 25-hydroxyvitamin D (25OHD) levels were determined at the same time. The cumulative dose of glucocorticoids was calculated in all patients. At 6 months, lumbar BMD decreased 5.2 ± 1.2 % (P=0.0005) and 2.9 ± 2.1 % (p=ns) in CyA and FK506 groups, respectively. Lumbar BMD reached baseline values at 1 year in the FK506 group and 2 years after LT in the CyA group. Moreover, significant intergroup differences in femoral neck BMD changes after 2 years of transplant were observed (CyA: −5.2 ± 1.97 versus FK506: +1.55 ± 2.2 %;P=0.039). In the first year posttransplant both groups showed a marked increase in PTH and 25OHD levels. The mean cumulative dose of glucocorticoids was higher in the CyA group (CyA group 11.06 ± 0.46 g versus FK 506 group 6.71 ± 0.42 g;P<0.001), and multiple linear regression analysis showed a negative correlation between BMD changes at the lumbar spine and mean cumulative dose of glucocorticoids (P=0.022). In conclusion, our data suggest that after liver transplantation treatment with FK506 shows a more favorable long-term effect on bone mass evolution than CyA therapy. These differences seem to be associated with the lower dose of glucocorticoids used in the FK506 group.     

FK506对许旺细胞体外增殖和分泌NGF的影响

目的 研究FK506促进许旺细胞体外增殖及对许旺细胞(SOs)分泌NGF的影响. 方法 将纯化的许旺细胞分6组:A组(空白对照组):含10%胎牛血清的DMEM/F12;B组:0.1 ng/mlFK506;C组:0.5 ng/ml FK506;D组:1.0 ng/ml FK506;E组:5.0 ng/mk FK506;F组:10 ng/ml FK506.将许旺细胞于倒置显微镜下观察并用S-100蛋白免疫组化染色鉴定;MTT法筛选FK506促SCs增殖的最佳作用浓度;流式细胞仪检测SCs周期;ELISA法检测培养72 h后SCs的NGF的分泌量. 结果 MTT法筛选:0.5 ng/ml FK506为促进SCs增殖的最佳作用浓度;当FK506浓度大于1.0 ng/ml时,SCs的生长活性逐渐下降并随着FK506浓度的逐渐增高,SCs的生长活性受抑制作用逐渐加强.流式细胞仪检测:含10%胎牛血清的DMEM/F12培养24 h、48 h、72 h,SCs S期百分比分别为:27.8%,39.3%和58.4%;0.5 ng/mlFK506培养24 h、48 h、72 h,SCs S期百分比分别为:54.2%、60.3%和94.6%.EUSA法检测FK506促SCs增殖后表达NGF的实验研究中发现:0.5 ng/ml FK506作用72 h后的SCs所分泌的NGF高达0.188 ng/ml. 结论 FK506应用于体外培养的SCs初期就能促进SCs增殖并使其保持良好的活性而高分泌NGF.     

Topical FK506 as immunoprophylaxis after allogeneic penetrating normal-risk keratoplasty: a randomized clinical pilot study

The purpose of this study was to evaluate for the first time the efficacy and safety of topical FK506 in patients undergoing penetrating normal-risk keratoplasty in a prospectively randomized clinical trial. Twenty patients were treated with FK506 0.06% three times per day for 6 months postoperatively. An additional 20 patients received five drops of prednisolone acetate 1% tapered within 6 months. All patients received 1 mg/kg bodyweight/day of systemic fluocortolon tapered within 3 weeks postoperatively. Clear graft survival, ratio of immune reactions and side effects were the main outcome measures. One year postoperatively all patients of the FK 506 group were free from immune reactions, in contrast to 84% in the steroid group (Kaplan-Meier values; P = 0.9 in the log rank test). None of the patients developed irreversible graft failure so far. In eight patients of the FK506 group premature withdrawal of the drug was deemed appropriate because of local side effects. FK506 might turn out to become an effective immunoprophylaxis in subjects undergoing penetrating normal-risk keratoplasty. Local discomfort should be further reduced.     

环孢素A及FK506对人肝癌细胞株增殖的影响

目的:探讨免疫抑制剂环孢素(CsA)及他克莫司(FK506)对肝癌细胞增殖的影响及可能机制。方法:采用噻唑蓝(MTT)比色法观察CsA及FK506对QGY鄄7701、QGY鄄7703、SMMC鄄7721和BEL鄄7402等4株肝癌细胞增殖的影响。还应用Hoechst33258荧光染料涂片,在荧光显微镜下观察用药组细胞的形态学改变。结果:随着作用时间延长,10μM的CsA对4株肝癌细胞均呈现明显的生长抑制效应(P<0.01),而0.5μM的FK506与对照组相比,其生长抑制作用不明显(P>0.05)。荧光显微镜下CsA用药组肝癌细胞呈现凋亡改变;而FK506用药组与对照组无显著差异。结论:免疫抑制剂CsA非但未促进体外肝癌细胞生长,相反呈明显的抑制效应。FK506尽管未呈现对肝癌细胞增殖的抑制效应,也未显示有生长促进作用。CsA对肝癌细胞的增殖抑制作用与诱导癌细胞发生凋亡有关。     

免疫抑制剂FK506在排斥反应中的应用及其肝肾毒性研究

目的:对排斥反应的分类,诊断标准及免疫抑制剂FK506的临床应用和肝肾毒性加以综述.方法:查阅近年来国内外相关文献,对其进行分析比较.结果:在器官移植领域,免疫抑制剂FK506具有高效,不良反应少等优点,但仍不可忽略其肝肾毒性.结论:FK506是一种很有前途的免疫抑制剂,以其众多优点和广泛作用逐渐成为器官移植和自身免疫性疾病的首选药物.     

FKBP12 Depletion Leads to Loss of Sarcoplasmic Reticulum Ca2+ Stores in Rat Vas Deferens

The immunophilin 12-kDa FK506 binding protein (FKBP12) stabilizes intracellular Ca²⁺ release channel (CRC) activity in different tissues. In this work, the presence of FKBP12 in rat vas deferens (RVD) and its possible contribution to RVD function was investigated. Treatment under appropriate pH, temperature, and ionic conditions was used to strip FKBP12 from CRC binding sites; Western blotting revealed FKBP12 in control but not in treated homogenates. Disruption of the FKBP12-CRC complex in RVD decreased the Ca²⁺ content of sarcoplasmic reticulum (SR) by increasing Ca²⁺ leakage through the ryanodine receptor (RyR3 isoform) but not through 1,4,5-iNOSitol trisphosphate receptors (IP₃R1 and IP₃R3 isoforms). The decrease of SR Ca²⁺ content was not related to inhibition of SERCA ATPase. It seems that dissociation of FKBP12-RyR leads to conformational changes in RyR that make it difficult for ryanodine to access its binding site. Rapamycin, which is commonly used as a pharmacological tool to disrupt the FKBP12-RyR complex, decreased phenylephrine-induced contractions in RVD epididymal halves. The data suggest that FKBP12 is expressed in RVD in a labile association with RyR3. Disruption of the FKBP12-RyR3 complex may lead to modifications of RVD physiology and in consequence may compromise male fertility.