Histological Analysis Of Brains Research Articles

In utero Exposure to Anesthetics Alters Neuronal Migration Pattern in Developing Cerebral Cortex and Causes Postnatal Behavioral Deficits in Rats.

During fetal development, cerebral cortical neurons are generated in the proliferative zone along the ventricles and then migrate to their final positions. To examine the impact of in utero exposure to anesthetics on neuronal migration, we injected pregnant rats with bromodeoxyuridine to label fetal neurons generated at embryonic Day (E) 17 and then randomized these rats to 9 different groups receiving 3 different means of anesthesia (oxygen/control, propofol, isoflurane) for 3 exposure durations (20, 50, 120min). Histological analysis of brains from 54 pups revealed that significant number of neurons in anesthetized animals failed to acquire their correct cortical position and remained dispersed within inappropriate cortical layers and/or adjacent white matter. Behavioral testing of 86 littermates pointed to abnormalities that correspond to the aberrations in the brain areas that are specifically developing during the E17. In the second set of experiments, fetal brains exposed to isoflurane at E16 had diminished expression of the reelin and glutamic acid decarboxylase 67, proteins critical for neuronal migration. Together, these results call for cautious use of anesthetics during the neuronal migration period in pregnancy and more comprehensive investigation of neurodevelopmental consequences for the fetus and possible consequences later in life.

Age differences in photodynamic therapy-mediated opening of the blood-brain barrier through the optical clearing skull window in mice.

Photodynamic therapy (PDT), a minimally invasive therapeutic tool, has been an important option for post-surgical treatment of malignant gliomas (MGs) in both adult and young patients. Recent studies have shown that PDT can also open the blood-brain barrier (BBB). However, there are no optimized parameters of PDT for patients at different ages. To determine whether there are age differences in PDT effects on the BBB, we studied PDT-related BBB opening through the optical clearing skull window in healthy 4- and 8-week-old mice. In this work, we realized BBB opening by combining PDT with the optical clearing skull window by using different radiant exposures (635 nm, 10-20-30-40 J/cm2 ) and 5-aminole-vulinic acid (5-ALA, 20 mg/kg). Then, we evaluated BBB permeability by: (i) spectrofluorimetric measuring of Evans Blue dye (EBd) leakage; (ii) confocal imaging of 70 kDa FITC-dextran extravasation and the BBB integrity; and (iii) histological analysis of brain tissues. Using the skull optical clearing method, we demonstrated PDT-induced BBB opening to EBd and FITC-dextran in a radiant exposure manner. The histological analysis revealed the different severities of vasogenic edema corresponding to radiant exposures. Besides, the PDT-related increase in the BBB permeability to high weight molecules (EBd and FITC-dextran) and solutes (vasogenic edema) was more pronounced in 4-week-old mice than in 8-week-old mice. The more pronounced PDT-induced BBB disruption in juvenile mice compared with adult mice suggests age differences in PDT-related BBB opening. This might be an important informative platform for a new application of PDT as a method for brain drug delivery, especially for post-surgical treatment of MGs. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Effect of Silver Ions on Copper Metabolism during Mammalian Ontogenesis

Copper metabolism was studied in laboratory rats that received silver ions with food (Ag diet) from birth for 5, 20, 40, and 180 days. Parameters of the copper status in the blood serum were determined, and data on the distribution of silver ions in the body were obtained. A comparative histological analysis of brain, liver, kidney, and spleen sections of adult rats kept on the Ag diet for 30 or 180 days was performed. Copper and silver content, expression levels of the genes of copper transport proteins, and the activity of copper enzymes were determined in the cells of the liver, the central organ responsible for copper metabolism in mammals. In adult rats kept on the Ag diet for 30 days, copper status parameters dropped to near-zero values. In contrast, these parameters were decreased only twofold in rats that had been kept on the Ag diet for 6 months from birth. At the same time, the expression of genes involved in copper homeostatis was downregulated. The expression of genes that encode copper enzymes was unchanged. The activity of ceruloplasmin, the main copper-containing protein of the blood, was decreased, while the activity of SOD1, a cellular copper enzyme, was unchanged. The pathways by which silver can interfere with copper metabolism and the mechanisms that compensate these effects are discussed. The data obtained may help assess the potential consequences of growing environmental exposure to silver due to increasing use of silver nanoparticles in different areas of human activity.

The effects of STZ-induced diabetes on cognition and brain amyloid in 5XFAD mouse model of Alzheimer’s disease

Introduction: Alzheimer’s disease (AD) is an incurable neurodegenerative disease characterized by progressive dementia. Main neuropathological features of AD include extracellular β-amyloid (Aβ)-containing plaques, intraneuronal aggregates of hyperphosphorylated τ-protein and neurofilaments, microglial activation and clustering around Aβ plaques and synaptic loss. 5XFAD transgenic mice are a model of AD, exhibiting rapid brain accumulation of Aβ and microgliosis. The aim of the study was to characterize the effects of streptozocin (STZ)-indced diabetes on learning and memory of 5XFAD and wild-type (WT) mice in Morris water maze (MWM) at ages 2 and 6 months and on brain amyloid load. Methods and results: Mice were injected with STZ 90 mg/kg or vehicle i.p., once daily for 2 consecutive days. MWM was performed on week 9 and histological analysis of brains of mice injected with STZ or vehicle at 2 months of age was performed on week 16. STZ treatment did not affect locomotion or vision of mice in MWM. At both 2 and 6 months of age, STZ treatment impaired memory of both 5XFAD and WT. Learning was significantly impaired in STZ-treatedc 5XFAD mice at 2 months. Surprisingly, Congo Red-positive area fraction (%) of hippocampus and amygdala was decreased 5XFAD mice treated with STZ at 2 months. Plaque diameter was not different between STZ treated and vehicle treated 5XFAD mice. Conclusions: Insulin deficiency could affect cognition through mechanisms unrelated to Aβ metabolism. Also different mechanisms may underlie effects of STZ treatment on learning and memory in different age gruops, possibly including enhancement of brain amyloid deposition and inhibition of neural cell precursor proliferation. We also hypothesize that STZ treatment might increase the soluble brain amyloid fraction in this model, since it is currently acknowledged that oligomeric (soluble) rather than fibrillar Aβ species disrupt cognitive function in AD.

Combining DC-mediated immunotherapy with oncolytic virotherapy in the treatment of HGG

Oncolytic viruses (OV) are either naturally selective for neoplastic cells or are engineered to be so. Whereas conservative therapies use the unspecific genome vulnerability of highly proliferating cells to target malignancies, OV have the advantage of often being extremely specific in infecting tumor cells. This (intrinsic) selectivity combined with the demonstrated safety and lack of host toxicity in phase I clinical studies make OV very appealing as novel cancer therapeutics. Recently, Alkassar et al. have shown in vitro and in vivo that naturally occurring Reovirus, Parvovirus and Newcastle disease virus (NDV) strains mediate strong anti-tumoral effects on glioblastoma. We hypothesize that upon combining a systemic immunotherapy approach with preceding oncolytic virotherapy (OVT), as a means of lowering the tumor viability and volume and altering the local micro environment within the tumor, a better immune control can be induced. In the immunotherapy field, it is known that the immunosuppressive microenvironment induced by the tumor can profoundly suppress the antitumor immunity and therefore inhibit vaccine efficacy. Viral presence within the tumor does the opposite; acting as a danger signal to alert and activate the immune system, it can reduce or eliminate the tumor induced immune suppression. Furthermore, the direct tumor cell killing effects of OV can lower tumor burden prior to immunotherapy. Both active specific immunotherapy and OVT have shown promising results in preclinical and clinical studies but the possible additive or synergistic effects of these treatment strategies have not been studied. We aim to combine OVT with dendritic cell (DC)-mediated immunotherapy in a preclinical murine glioma model to demonstrate additive or synergistic effects. Our initial results show good susceptibility of the murine GL261 glioma cell line to cytotoxic killing by oncolytic Reovirus, Parvovirus and NDV in vitro. The strains were also combined to exploit the synergism recently demonstrated by Alkassar et al. Results indicate increased cytotoxic effects when Reovirus was combined with NDV or when Reovirus was combined with Parvovirus. GL261 cell infection capacity of the viruses was quantified by immunofluorescence imaging. In vivo, intracranial injection of Reovirus, Parvovirus, NDV or combinations of two viruses in healthy mice led to signs of inflammation in the brain, as visualized by MR imaging. Infiltration of inflammatory cells will be confirmed by histology. In tumor-bearing mice, prolonged survival and induction of long term survival was seen when mice were treated intra tumorally with Reovirus, Parvovirus or a combination of both. Similar results were found when tumor-bearing mice were treated with NDV and/or Reovirus. Toxicity of the viruses will be analyzed by histological analysis of brain and other vital organs.

Brain MR Imaging and Proton MR Spectroscopy in Female Mice with Pyruvate Dehydrogenase Complex Deficiency

Pyruvate dehydrogenase complex (PDC) deficiency is an inborn metabolic disorder that causes neurological abnormalities. In this report, a murine model of PDC deficiency was analyzed using histology, magnetic resonance (MR) imaging and MR spectroscopy (MRS) and the results compared to PDC-deficient female patients. Histological analysis of brains from PDC-deficient mice revealed defects in neuronal cytoarchitecture in grey matter and reduced size of white matter structures. MR results were comparable to previously published clinical MR findings obtained from PDC-deficient female patients. Specifically, a 15.4% increase in relative lactate concentration, 64.4% loss of N-acetylaspartate concentration and a near complete loss of discernable glutamine plus glutamate concentration were observed in a PDC deficient mouse compared to wild-type control. Lower apparent diffusion coefficients (ADCs) were observed within the brain consistent with atrophy. These results demonstrate the usefulness of this murine model to systematically evaluate the beneficial effects of dietary and pharmacological interventions.

2,3,7,8-Tetrachlorodibenzo-p-Dioxin (TCDD) Induces Organ- Specific Differential Gene Expression in Male Japanese Medaka (Oryzias latipes)

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a ubiquitous environmental contaminant with well-known adverse effects in fish. In this study, we initially exploited suppression subtractive hybridization (SSH) as a screening tool to assess qualitative gene expression changes in whole brain, liver, and testis of adult male Japanese medaka (Oryzias latipes) exposed for 48 h to a single intraperitoneal-injected dose of TCDD (10 microg TCDD/kg body weight). Across these three organs, SSH identified a total of 335 unique genes. Each set of forward- and reverse-subtracted organ cDNA libraries consisted of a distinct gene list and corresponding distribution of biological processes, suggesting that transcript profiles of these libraries were highly organ-specific. Based on sequence match significance and frequencies within each set of organ libraries, genes hypothesized to be strongly responsive (42 total) within male medaka brain, liver, or testis were semi-quantitatively screened with replicate cDNA nylon membrane arrays. In addition, TCDD-treated male medaka were surveyed for gross histological analysis of brain, liver, and testis. In general, adverse histopathological changes were not observed in the brain, and glycogen depletion was observed only in the liver. However, significant histological changes occurred in the testis, and included disorganization of spermatogenesis at the testis periphery, disruption of the interstitium, Leydig cell swelling, and Sertoli cell vacuolation. Of the 42 genes screened by cDNA array analysis, cytochrome P450 1A (CYP1A) mRNA was the only transcript significantly higher in TCDD-exposed brain, whereas 12 transcripts (including CYP1A) were significantly higher in TCDD-exposed liver, and 34 transcripts were significantly lower in TCDD-exposed testis. Therefore, the degree of TCDD-induced alterations observed in each organ at a gross histological level corresponded well with the number and ontology of gene transcripts affected on the array. Based on real-time reverse transcription polymerase chain reaction (RT-PCR), relative CYP1A (but not AHR1) transcript levels were confirmed to be significantly higher in TCDD-treated brain and liver. However, CYP1A was not significantly induced in TCDD-exposed testis, suggesting that gene expression and histopathological responses observed in the testis at 48 h may be CYP1A-independent. Based on these data, unique liver-specific and testis-specific mRNA-level targets in male medaka were identified as promising biomarkers of acute TCDD-induced toxicity.

Forebrain ischemia in the gerbil increases λ opiate binding in hippocampal mossy fibers

Transient forebrain ischemia was produced in gerbils by short-term occlusion of the common carotid arteries under halothane anesthesia. Histological analysis of brains 7 days post-ischemia demonstrated characteristic destruction of CA1 pyramidal cells. λ Opiate binding (measured with [ 3H]naloxone in the presence of 300 nM diprenorphine) at 7 days post-ischemia was significantly increased in the stratum lucidum of the hippocampus (the mossy fiber layer), but not in any other region measured, including other hippocampal regions, cortex, amygdala, caudate putamen, thalamus, and hypothalamus. The increase in mossy fiber λ binding was slow to develop (no increase detected up to 48 h post-ischemia), and long-lasting (binding remained elevated at 32 days post-ischemia). While MK-801 significantly inhibited CA1 pyramidal cell destruction when administered 20 min prior to ischemia, the increase in mossy fiber λ binding was still evident. None of seven different opioid agonists and antagonists examined had an effect on either the pyramidal cell damage or increased mossy fiber λ binding seen 7 days after ischemia.

Carrageenan-induced brain inflammation. Characterization of the model.

Administration of the mucopolysaccharide, carrageenan (CAR), into the hind paw of the rat or mouse induces a local inflammation characterized by increased arachidonic acid metabolism, increased vascular permeability, edema, and neutrophil extravasation. Carrageenan-induced hind-paw inflammation is inhibited by prostaglandin synthesis inhibitors, and this assay predicts the clinical success of anti-inflammatory agents in reducing peripheral inflammation. The purpose of this study was to determine if intraventricular injection of CAR would induce brain inflammation similar to that evoked by CAR in peripheral tissues. The present study demonstrates that CAR injection into the ventricles of the mouse brain does in fact induce an inflammatory response very similar to that caused by injection of CAR into the peripheral tissues. The brain response to CAR was dose-dependent, with the maximum increase in cerebrovascular permeability to iodine-125-labeled human serum albumin and percent brain water occurring after injection of 50 micrograms CAR. As is seen in CAR-induced inflammation of the hind paw, the maximum increase in brain vascular permeability occurred 4 hours after CAR injection. Histological analysis of brains 4 hours after CAR administration showed global neutrophil extravasation into the subarachnoid space and evidence of focal neuronal swelling. Methotrexate-induced neutropenia, however, failed to diminish the permeability response to CAR. Gas chromatographic and mass spectrometric measurements of brain prostaglandins 4 hours after CAR injection revealed a significantly increased level of 6-keto-prostaglandin F1 alpha. These results indicate that a significant increase in prostacyclin, the pro-inflammatory arachidonic acid metabolite, during CAR-induced brain inflammation is likely. These studies suggest that CAR-induced brain inflammation may be a useful model on which to test the efficacy of anti-inflammatory agents in the brain, as well as providing information concerning the mediators and mechanisms by which the brain may sustain inflammatory injury.