Does Chronic Low-Dose Treatment With Cyclosporine Influence the Brain? A Histopatological Study in Pigs

Impact of calcineurin inhibitors on rat glioma cells viability

Background

Although kidney transplantation outcomes have improved dramatically after using calcineurin inhibitors (CNIs), CNI toxicity continues to be reported and the mechanism remains uncertain. Here, we investigated the neurotoxicity of CNIs by focusing on the viability of glioma cells.

Methods

Glioma cells were treated with several concentrations of CNIs for 24 hours at 37℃ and their cell viability was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.

Results

Exposure to 0, 0.25, 0.5, 2.5, 5.0, and 10.0 mM concentrations respectively showed 100%, 64.3%, 61.3%, 68.1%, 62.4%, and 68.6% cell viability for cyclosporine and 100%, 38.6%, 40.8%, 43.7%, 37.8%, and 43.0% for tacrolimus. The direct toxic effect of tacrolimus on glioma cell viability was stronger than that of cyclosporine at the same concentration.

Conclusion

CNIs can cause neurological side effects by directly exerting cytotoxic effects on brain cells. Therefore, we should carefully monitor the neurologic symptoms and level of CNIs in kidney transplant patients.

Insights into Pathophysiology from Medication-induced Tremor

Background

Medication-induced tremor (MIT) is common in clinical practice and there are many medications/drugs that can cause or exacerbate tremors. MIT typically occurs by enhancement of physiological tremor (EPT), but not all drugs cause tremor in this way. In this manuscript, we review how some common examples of MIT have informed us about the pathophysiology of tremor.

Methods

We performed a PubMed literature search for published articles dealing with MIT and attempted to identify articles that especially dealt with the medication's mechanism of inducing tremor.

Results

There is a paucity of literature that deals with the mechanisms of MIT, with most manuscripts only describing the frequency and clinical settings where MIT is observed. That being said, MIT emanates from multiple mechanisms depending on the drug and it often takes an individualized approach to manage MIT in a given patient.

Discussion

MIT has provided some insight into the mechanisms of tremors we see in clinical practice. The exact mechanism of MIT is unknown for most medications that cause tremor, but it is assumed that in most cases physiological tremor is influenced by these medications. Some medications (epinephrine) that cause EPT likely lead to tremor by peripheral mechanisms in the muscle (β-adrenergic agonists), but others may influence the central component (amitriptyline). Other drugs can cause tremor, presumably by blockade of dopamine receptors in the basal ganglia (dopamine-blocking agents), by secondary effects such as causing hyperthyroidism (amiodarone), or by other mechanisms. We will attempt to discuss what is known and unknown about the pathophysiology of the most common MITs.

Exposure of the Pig CNS for Histological Analysis: A Manual for Decapitation, Skull Opening, and Brain Removal

Pigs have become increasingly popular in large-animal translational neuroscience research as an economically and ethically feasible substitute to non-human primates. The large brain size of the pig allows the use of conventional clinical brain imagers and the direct use and testing of neurosurgical procedures and equipment from the human clinic. Further macroscopic and histological analysis, however, requires postmortem exposure of the pig central nervous system (CNS) and subsequent brain removal. This is not an easy task, as the pig CNS is encapsulated by a thick, bony skull and spinal column. The goal of this paper and instructional video is to describe how to expose and remove the postmortem pig brain and the pituitary gland in an intact state, suitable for subsequent macroscopic and histological analysis.

The telencephalon of the Göttingen minipig, cytoarchitecture and cortical surface anatomy

During the last 20 years pigs have become increasingly popular in large animal translational neuroscience research as an economical and ethical feasible substitute to non-human primates. The anatomy of the pig telencephalon is, however, not well known. We present, accordingly, a detailed description of the surface anatomy and cytoarchitecture of the Göttingen minipig telencephalon based on macrophotos and consecutive high-power microphotographs of 15 μm thick paraffin embedded Nissl-stained coronal sections. In 1-year-old specimens the formalin perfused brain measures approximately 55 × 47 × 36 mm (length, width, height) and weighs around 69 g. The telencephalic part of the Göttingen minipig cerebrum covers a large surface area, which can be divided into a neocortical gyrencephalic part located dorsal to the rhinal fissure, and a ventral subrhinal part dominated by olfactory, amygdaloid, septal, and hippocampal structures. This part of the telencephalon is named the subrhinal lobe, and based on cytoarchitectural and sulcal anatomy, can be discerned from the remaining dorsally located neocortical perirhinal/insular, pericallosal, frontal, parietal, temporal, and occipital lobes. The inner subcortical structure of the minipig telencephalon is dominated by a prominent ventricular system and large basal ganglia, wherein the putamen and the caudate nucleus posterior and dorsally are separated into two entities by the internal capsule, whereas both structures ventrally fuse into a large accumbens nucleus. The presented anatomical data is accompanied by surface renderings and high-power macrophotographs illustrating the telencephalic sulcal pattern, and the localization of the identified lobes and cytoarchitectonic areas. Additionally, 24 representative Nissl-stained telencephalic coronal sections are presented as supplementary material in atlas form on http://www.cense.dk/minipig_atlas/index.html and referred to as S1-S24 throughout the manuscript.

New surgical technique reduces the susceptibility artefact at air-tissue interfaces on in vivo cerebral MRI in the Göttingen minipig

Advanced and exclusive software solutions are offered to reduce susceptibility artefacts on MRI echo-planar sequences. We present a straightforward surgical technique to reduce the cortical distortion and signal loss that normally occur using diffusion tensor imaging (DTI) of the Göttingen minipig brain. Pronounced pneumatisation of the minipig cranium causes considerable susceptibility artefacts at the air/tissue interface around the frontal sinuses. Five Göttingen minipigs had burr holes drilled through the outer lamina of the skull bilaterally at the level of bregma. The underlying frontal sinuses were filled with a suspension of an MRI-compatible alginate. DTI was obtained before and after placing the medium in the sinus, quantifying the change using mutual information and Wilcoxon's rank-sum test. Fibertracking algorithms were applied to visualize the effect of treatment. We showed that the susceptibility artefacts were reduced at the air, bone and brain interfaces and that major cortical fiberbundles could be reliably visualized. This study demonstrated that DTI fibertracking of cortical bundles in experimental animals with extensive skull pneumatisation is feasible even when advanced software is unavailable.

Effects of cyclosporine on the production of the reactive oxygen species in the glial cells

OBJECTIVES

After organ transplantation, some patients suffer mild neurological symptoms such as tremor to severe complications including seizures and encephalopathy. Among the immunosuppressants, cyclosporine (CsA) can induce neurological side effects. However, the mechanisms of encephalopathy by CsA are not fully understood. We measured the production of reactive oxygen species (ROS) in the glioma cells after CsA treatment.

METHODS

CsA (2.5 mmol/L) added to glioma cells was incubated for 60 minutes at 37 degrees C. ROS production was evaluated by measuring the fluorescent product from the oxidation of an oxidant-sensitive 2',7'-dichlorofluorescin using VICTOR3 multilabel counter.

RESULTS

CsA resulted in ROS production by glioma cells. The ROS production increased with the time of exposure to CsA.

CONCLUSIONS

These findings indicated that CsA may contribute to neurological side effects via ROS production.

Cyclosporine A inhibits acetylcholinesterase activity in rats experimentally demyelinated with ethidium bromide

Cyclosporine A is the major immunosuppressive agent used for organ transplantation and for the treatment of a variety of autoimmune disorders such as multiple sclerosis. In this work, we investigated the effect of the cyclosporine A on the acetylcholinesterase activity in the cerebral cortex, striatum, hippocampus, hypothalamus, cerebellum and pons of the rats experimentally demyelinated by ethidium bromide. Rats were divided into four groups: I control (injected with saline), II (treated with cyclosporine A), III (injected with 0.1% ethidium bromide) and IV (injected with 0.1% the ethidium bromide and treated with cyclosporine A). The results showed a significant inhibition (p<0.05) of acetylcholinesterase activity in the groups II, III and IV in all brain structures analyzed. In the striatum, hippocampus, hypothalamus and pons the inhibition was greater (p<0.005) when ethidium bromide was associated with cyclosporine A. In conclusion, the present investigation demonstrated that cyclosporine A is an inhibitor of acetylcholinesterase activity and this effect is increased after an event of toxic demyelination of the central nervous system.