Adult Rat Brain Research Articles

Neural Organoids Making Connections, Getting Real

Neural Organoids Making Connections, Getting Real

Changes in the histopathology and in the proteins related to the MAPK pathway in the brains of rats exposed to pre and postnatal radiofrequency radiation over four generations

The development of new technologies and industry increases the number and variety of electromagnetic field (EMF) sources. Researcher are increasingly interested in the effects of EMF on brain health. The brain's function is largely dependent on electrical excitability, so it would be expected to be vulnerable to EMF. We therefore investigated the effects of brain development in the fetus, histopathological changes in female rats and the hippocampal level of MAPK proteins in male rats after exposed to pre and postnatal 2450 MHz continuous wave (CW) radiofrequency radiation (RFR) over four generations. Four groups; sham, irradiated female, irradiated male, irradiated male and female, with each consisting of four rats (one male and three females) were created. Rats in the exposure groups were whole-body exposed to 2450 MHz CW-RFR for 12 h/day during the experiment. Irradiation started one month before fertilization in the experimental group. On the 18th day of the gestational period, one pregnant rat from each group was decapitated under general anesthesia and the fetuses were taken. The remaining two pregnant rats completed the normal gestation period. When the offspring were two months old, four rats, one male and three female, were allocated for the second generation study. Next generation animals were also experienced the same processes as the first generation rats. This study were evaluated development of brain in fetuses and histopathological changes in brain of female rats using haematoxylin eosin staining, and the hippocampal level of MAPK proteins in brain of male rats by Western Bloting. We observed hemorrhagic areas, irregular cellular localization and vascular structures in the brain of fetal and adult female rat of exposed groups in the all generations. pERK, ptau, pJNK and pP38 were increased in the brain of adult male rat of exposed groups in the all generations (p < 0.005). Pre and postnatal 2450 MHz continuous wave radiofrequency radiation exposure may cause changes in the function of the MAPK pathway affecting cognitive processes such as learning and memory and may cause damage to both the fetus and adult brain tissue. Also, EMF may have potential to affect brain of future generations.

The transcriptome of rat hippocampal subfields.

The hippocampus comprises several neuronal populations such as CA1, CA2, CA3, and the dentate gyrus (DG), which present different neuronal origins, morphologies, and molecular mechanisms. Laser capture microdissection (LCM) allows selectively collecting samples from target regions and eliminating unwanted cells to obtain more specific results. LCM of hippocampus neuronal populations coupĺed with RNA-seq analysis has the potential to allow the exploration of the molecular machinery unique to each of these subfields. Previous RNA-seq investigation has already provided a molecular blueprint of the hippocampus, however, there is no RNA-seq data specific for each of the rat hippocampal regions. Serial tissue sections covering the hippocampus were produced from frozen brains of adult male Wistar rats, and the hippocampal subfields CA1, CA2, CA3, and DG were identified and isolated by LCM. We found evident segregation of the transcriptomic profile from different regions of the hippocampus and the expression of known, as well as novel, specific marker genes for each region. Gene ontology enrichment analysis of CA1 subfield indicates an enrichment of actin regulation and postsynaptic membrane AMPA receptors genes indispensable for long-term potentiation. CA2 and CA3 transcripts were found associated with the increased metabolic processes. DG expression was enriched for ribosome and spliceosome, both required for protein synthesis and maintenance of cell life. The present findings contribute to a deeper understanding of the differences in the molecular machinery expressed by the rat hippocampal neuronal populations, further exploring underlying mechanisms responsible for each subflied specific functions.

Design and validation of recombinant protein standards for quantitative Western blot analysis of cannabinoid CB1 receptor density in cell membranes: an alternative to radioligand binding methods

BackgroundReplacement of radioligand binding assays with antibody-antigen interaction-based approaches for quantitative analysis of G protein-coupled receptor (GPCR) levels requires the use of purified protein standards containing the antigen. GPCRs in general and cannabinoid CB1 receptor in particular show a progressive tendency to aggregate and precipitate in aqueous solution outside of their biological context due to the low solubility that the hydrophobic nature imprinted by their seven transmembrane domains. This renders full-length recombinant GPCRs useless for analytical purposes, a problem that can be overcome by engineering soluble recombinant fragments of the receptor containing the antigen.ResultsHere we generated highly soluble and stable recombinant protein constructs GST-CB1414–472 and GST-CB1414-442 containing much of the human CB1 receptor C-terminal tail for use as standard and negative control, respectively, in quantitative Western blot analysis of CB1 receptor expression on crude synaptosomes of the adult rat brain cortex. To this end we used three different antibodies, all raised against a peptide comprising the C-terminal residues 443–473 of the mouse CB1 receptor that corresponds to residues 442–472 in the human homolog. Estimated values of CB1 receptor density obtained by quantitative Western blot were of the same order of magnitude but slightly higher than values obtained by the radioligand saturation binding assay.ConclusionsCollectively, here we provide a suitable Western blot-based design as a simple, cost-effective and radioactivity-free alternative for the quantitative analysis of CB1 receptor expression, and potentially of any GPCR, in a variety of biological samples. The discrepancies between the results obtained by quantitative Western blot and radioligand saturation binding techniques are discussed in the context of their particular theoretical bases and methodological constraints.

Sex-Related Differences in Voluntary Alcohol Intake and mRNA Coding for Synucleins in the Brain of Adult Rats Prenatally Exposed to Alcohol.

Maternal alcohol consumption is one of the strong predictive factors of alcohol use and consequent abuse; however, investigations of sex differences in response to prenatal alcohol exposure (PAE) are limited. Here we compared the effects of PAE throughout gestation on alcohol preference, state anxiety and mRNA expression of presynaptic proteins α-, β- and γ-synucleins in the brain of adult (PND60) male and female Wistar rats. Total RNA was isolated from the hippocampus, midbrain and hypothalamus and mRNA levels were assessed with quantitative RT-PCR. Compared with naïve males, naïve female rats consumed more alcohol in “free choice” paradigm (10% ethanol vs. water). At the same time, PAE produced significant increase in alcohol consumption and preference in males but not in females compared to male and female naïve groups, correspondingly. We found significantly lower α-synuclein mRNA levels in the hippocampus and midbrain of females compared to males and significant decrease in α-synuclein mRNA in these brain areas in PAE males, but not in females compared to the same sex controls. These findings indicate that the impact of PAE on transcriptional regulation of synucleins may be sex-dependent, and in males’ disruption in α-synuclein mRNA expression may contribute to increased vulnerability to alcohol-associated behavior.

Electrochemical and biological performance of hierarchical platinum-iridium electrodes structured by a femtosecond laser

Neural electrode interfaces are essential to the stimulation safety and recording quality of various bioelectronic therapies. The recently proposed hierarchical platinum-iridium (Pt-Ir) electrodes produced by femtosecond lasers have exhibited superior electrochemical performance in vitro, but their in vivo performance is still unclear. In this study, we explored the electrochemical performance, biological response, and tissue adhesion of hierarchical Pt-Ir electrodes by implantation in adult rat brains for 1, 8, and 16 weeks. Regular smooth Pt-Ir electrodes were used as a control. The results showed that the electrochemical performance of both electrodes decreased and leveled off during implantation. However, after 16 weeks, the charge storage capacity of hierarchical electrodes stabilized at ~16.8 mC/cm2, which was 15 times that of the smooth control electrodes (1.1 mC/cm2). Moreover, the highly structured electrodes had lower impedance amplitude and cutoff frequency values. The similar histological response to smooth electrodes indicated good biocompatibility of the hierarchically structured Pt-Ir electrodes. Given their superior in vivo performance, the femtosecond laser-treated Pt-Ir electrode showed great potential for neuromodulation applications.

Immunofluorescent Evidence for Nuclear Localization of Aromatase in Astrocytes in the Rat Central Nervous System.

Estrogens regulate a variety of neuroendocrine, reproductive and also non-reproductive brain functions. Estradiol biosynthesis in the central nervous system (CNS) is catalyzed by the enzyme aromatase, which is expressed in several brain regions by neurons, astrocytes and microglia. In this study, we performed a complex fluorescent immunocytochemical analysis which revealed that aromatase is colocalized with the nuclear stain in glial fibrillary acidic protein (GFAP) positive astrocytes in cell cultures. Confocal immunofluorescent Z-stack scanning analysis confirmed the colocalization of aromatase with the nuclear DAPI signal. Nuclear aromatase was also detectable in the S100β positive astrocyte subpopulation. When the nuclear aromatase signal was present, estrogen receptor alpha was also abundant in the nucleus. Immunostaining of frozen brain tissue sections showed that the nuclear colocalization of the enzyme in GFAP-positive astrocytes is also detectable in the adult rat brain. CD11b/c labelled microglial cells express aromatase, but the immunopositive signal was distributed only in the cytoplasm both in the ramified and amoeboid microglial forms. Immunostaining of rat ovarian tissue sections and human granulosa cells revealed that aromatase was present only in the cytoplasm. This novel observation suggests a new unique mechanism in astrocytes that may regulate certain CNS functions via estradiol production.

Age-Specific Features of the Levels of Reference Proteins Actin, Tubulin, and GAPDH in Different Organs of Male Wistar Rats.

Western blot analysis is used for evaluation of the level of proteins production in organs and tissues, and housekeeping proteins GAPDH, actin, and tubulin are usually used as the reference proteins. The signal of the target protein is normalized to the corresponding signal of the reference protein. The data on the intensity of actin, tubulin, and GAPDH synthesis are fragmentary: their expression differs in different organs and can vary depending on age, which is often not taken into account in experimental studies. We studied the features of the production of reference proteins in the liver, heart, brain, and lungs of newborn, prepubertal, and adult male Wistar rats. Age-related differences in the expression of β-actin, β-tubulin, and GAPDH in the myocardium and dorsal prefrontal cortex were revealed. GAPDH expression in the dorsal prefrontal cortex in adult rats was significantly higher than in prepubertal rats; GAPDH expression in the myocardium of adult rats was significantly higher than in newborns. The level of actin in the dorsal prefrontal cortex in newborn rats was significantly higher than in prepubertal and adult rats. In the liver and lungs, the expression of actin, tubulin, and GAPDH did not differ in newborn, prepubertal, and adult rats. When choosing the reference protein for Western blotting, animals age and the studied organ should be taken into account.

Abstract TMP113: Conditional Expression Of Mir-20a-3p In Neurons Versus Astrocytes And Its Impact On Acute Stroke Outcomes

Introduction: MiR-20a-3p was found to be upregulated in the brains of adult female rats, who typically sustain smaller infarcts, compared to that of middle-aged rats, who typically sustain larger infarcts. In fact, qRT-PCR analysis shows that miR-20a-3p is profoundly upregulated (&gt;240,000-fold elevation) in adult astrocytes post-stroke, while ischemic neurons do not exhibit this upregulation. Intravenous injections of miR-20a-3p mimic, given 4h after stroke, reduced infarct size and improved sensory motor function in middle-aged rats, and surprisingly exogenous miR-20a-3p was preferentially taken up by neurons . To better understand the cellular target of this miRNA, we compared the efficacy of conditional expression of miR-20a-3p in neurons versus astrocytes in improving acute stroke outcomes. Methods: Two viral vectors to conditionally express miR-20a-3p in neurons (rAAV5-TetOn-NSE-miR-20a-3p-mCherry) and astrocytes (rAAV5-TetOn-GFAP-miR-20a-3p-mCherry) were injected into the striatum of middle-aged female rats.Control subjects were given an identical vector minus miR-20a-3p. After 6 weeks, the rats were subjected to middle cerebral artery occlusion, and the virus was activated by i.p. doxycycline 4h post-stroke. Behavioral assessments were performed at 2d and 5d. Animals were terminated at 5d, and infarct size was assessed. Results: Astrocytic miR-20a-3p improved survival compared to control (p=0.0372), and neuronal miR-20a-3p showed a trend for improved survival (p=0.0805). Neuronal miR-20a-3p reduced latency on the adhesive removal task at 2d and 5d, while astrocytic miR-20a-3p demonstrated modest improvement only at 5d. Moreover, neuronal miR-20a-3p significantly reduced infarct size relative to control (p=0.0087), while astrocytic miR-20a-3p did not improve infarct size(p=0.1117). Conclusions: Both rAAVs resulted in improvement in stroke outcomes; however, the results from the neuronal vector were much more robust. The fact that astrocytes upregulate miR-20a-3p after stroke yet neurons more efficiently use the miRNA to improve stroke outcome suggest that this miRNA may be transferred from astrocytes to neurons to confer neuroprotection. Supported by RFAG042189 to FS and 1F31NS118970-01A to TEB.

Adaptive polymer fiber neural device for drug delivery and enlarged illumination angle for neuromodulation

Objective. Optical fiber devices constitute significant tools for the modulation and interrogation of neuronal circuitry in the mid and deep brain regions. The illuminated brain area during neuromodulation has a direct impact on the spatio-temporal properties of the brain activity and depends solely on the material and geometrical characteristics of the optical fibers. In the present work, we developed two different flexible polymer optical fibers (POFs) with integrated microfluidic channels (MFCs) and an ultra-high numerical aperture (UHNA) for enlarging the illumination angle to achieve efficient neuromodulation. Approach. Three distinct thermoplastic polymers: polysulfone, polycarbonate, and fluorinated ethylene propylene were used to fabricate two step-index UHNA POF neural devices using a scalable thermal drawing process. The POFs were characterized in terms of their illumination map as well as their fluid delivery capability in phantom and adult rat brain slices. Main results. A 100-fold reduced bending stiffness of the proposed fiber devices compared to their commercially available counterparts has been found. The integrated MFCs can controllably deliver dye (trypan blue) on-demand over a wide range of injection rates spanning from 10 nl min−1 to 1000 nl min−1. Compared with commercial silica fibers, the proposed UHNA POFs exhibited an increased illumination area by 17% and 21% under 470 and 650 nm wavelength, respectively. In addition, a fluorescent light recording experiment has been conducted to demonstrate the ability of our UHNA POFs to be used as optical waveguides in fiber photometry. Significance. Our results overcome the current technological limitations of fiber implants that have limited illumination area and we suggest that soft neural fiber devices can be developed using different custom designs for illumination, collection, and photometry applications. We anticipate our work to pave the way towards the development of next-generation functional optical fibers for neuroscience.

Early maternal separation alters the activation of stress-responsive brain areas in adulthood

The expression of c-Fos protein has been extensively used as a marker of neuronal activation in response to stressful stimuli. Early maternal separation (MS) is a model of early life adversity that affects the responsiveness of the brain areas to stressors. Thus, this study examined the impact of early MS on activating stress-responsive areas in the brain of adult rats in response to physical (ether) or psychological (restraint) stressors. Male pups were divided for the MS or non-handled (NH) groups. The MS was carried out daily between the 2nd and 14th day of postnatal life and consisted in removing the dams from the cage for 180 min. The rats were then subjected to experimental protocols of restraint or ether exposure at 10–12 weeks old. The rats were anesthetized 90 min after exposure to the stressors, and their brains were prepared for immunohistochemical analysis of c-Fos immunoreactive (c-Fos-ir) neurons in the hypothalamic paraventricular nucleus (PVN), supraoptic nucleus (SON), medial preoptic area (MPA), medial amygdaloid nucleus (MeA), locus coeruleus (LC), and nucleus of the solitary tract (NST). The MS-group presented 86%, 125%, 73%, 56%, and 137% higher c-Fos-ir neurons in the LC, PVN, SON, MPA, and MeA, respectively, compared to NH-group in response to the restraint stressor. In addition, the MS-group presented 180%, 137%, 170%, and 138% higher c-Fos-ir neurons for the ether exposure in the LC, PVN, MPA, and MeA, respectively. Our results show a greater increase in neuronal activation in the MS group, indicating that early life adversity can induce reprogramming in the brain response to stress in adulthood.

Spatial and temporal dynamics of HDACs class IIa following mild traumatic brain injury in adult rats.

The fundamental role of epigenetic regulatory mechanisms involved in neuroplasticity and adaptive responses to traumatic brain injury (TBI) is gaining increased recognition. TBI-induced neurodegeneration is associated with several changes in the expression-activity of various epigenetic regulatory enzymes, including histone deacetylases (HDACs). In this study, PET/CT with 6-([18F]trifluoroacetamido)-1- hexanoicanilide ([18F]TFAHA) to image spatial and temporal dynamics of HDACs class IIa expression-activity in brains of adult rats subjected to a weight drop model of diffuse, non-penetrating, mild traumatic brain injury (mTBI). The mTBI model was validated by histopathological and immunohistochemical analyses of brain tissue sections for localization and magnitude of expression of heat-shock protein-70 kDa (HSP70), amyloid precursor protein (APP), cannabinoid receptor-2 (CB2), ionized calcium-binding adapter protein-1 (IBA1), histone deacetylase-4 and -5 (HDAC4 and HDAC5). In comparison to baseline, the expression-activities of HDAC4 and HDAC5 were downregulated in the hippocampus, nucleus accumbens, peri-3rd ventricular part of the thalamus, and substantia nigra at 1-3 days post mTBI, and remained low at 7-8 days post mTBI. Reduced levels of HDAC4 and HDAC5 expression observed in neurons of these brain regions post mTBI were associated with the reduced nuclear and neuropil levels of HDAC4 and HDAC5 with the shift to perinuclear localization of these enzymes. These results support the rationale for the development of therapeutic strategies to upregulate expression-activity of HDACs class IIa post-TBI. PET/CT (MRI) with [18F]TFAHA can facilitate the development and clinical translation of unique therapeutic approaches to upregulate the expression and activity of HDACs class IIa enzymes in the brain after TBI.

Age-Specific Adult Rat Brain MRI Templates and Tissue Probability Maps.

Age-specific resources in human MRI mitigate processing biases that arise from structural changes across the lifespan. There are fewer age-specific resources for preclinical imaging, and they only represent developmental periods rather than adulthood. Since rats recapitulate many facets of human aging, it was hypothesized that brain volume and each tissue's relative contribution to total brain volume would change with age in the adult rat. Data from a longitudinal study of rats at 3, 5, 11, and 17 months old were used to test this hypothesis. Tissue volume was estimated from high resolution structural images using a priori information from tissue probability maps. However, existing tissue probability maps generated inaccurate gray matter probabilities in subcortical structures, particularly the thalamus. To address this issue, gray matter, white matter, and CSF tissue probability maps were generated by combining anatomical and signal intensity information. The effects of age on volumetric estimations were then assessed with mixed-effects models. Results showed that herein estimation of gray matter volumes better matched histological evidence, as compared to existing resources. All tissue volumes increased with age, and the tissue proportions relative to total brain volume varied across adulthood. Consequently, a set of rat brain templates and tissue probability maps from across the adult lifespan is released to expand the preclinical MRI community's fundamental resources.

Expression of Ectonucleoside Triphosphate Diphosphohydrolase 2 (NTPDase2) Is Negatively Regulated Under Neuroinflammatory Conditions In Vivo and In Vitro.

Ectonucleoside triphosphate diphosphohydrolase 2 (NTPDase2) hydrolyzes extracellular ATP to ADP, which is the ligand for P2Y1,12,13 receptors. The present study describes the distribution of NTPDase2 in adult rat brains in physiological conditions, and in hippocampal neurodegeneration induced by trimethyltin (TMT). The study also describes the regulation of NTPDase2 by inflammatory mediators in primary astrocytes and oligodendroglial cell line OLN93. In physiological conditions, NTPDase2 protein was most abundant in the hippocampus, where it was found in fibrous astrocytes and synaptic endings in the synaptic-rich hippocampal layers. In TMT-induced neurodegeneration, NTPDase2-mRNA acutely decreased at 2-dpi and then gradually recovered to the control level at 7-dpi and 21-dpi. As determined by immunohistochemistry and double immunofluorescence, the decrease was most pronounced in the dentate gyrus (DG), where NTPDase2 withdrew from the synaptic boutons in the polymorphic layer of DG, whereas the recovery of the expression was most profound in the subgranular layer. Concerning the regulation of NTPDase2 gene expression, proinflammatory cytokines IL-6, IL-1β, TNFα, and IFNγ negatively regulated the expression of NTPDase2 in OLN93 cells, while did not altering the expression in primary astrocytes. Different cell-intrinsic stressors, such as depletion of intracellular energy store, oxidative stress, endoplasmic reticulum stress, and activation of protein kinase C, also massively disturbed the expression of the NTPDase2 gene. Together, our results suggest that the expression and the activity of NTPDase2 transiently cease in neurodegeneration and brain injury, most likely as a part of the acute adaptive response designed to promote cell defense, survival, and recovery.

Spatio-temporal distribution of reactive sulfur species during methylmercury exposure in the rat brain.

Brain susceptibility to methylmercury (MeHg) is developmentally and regionally specific in both humans and rodents, but the mechanism is not well clarified. Reactive sulfur species (RSS) with high nucleophilicity can react with MeHg, leading to the formation of a less toxic metabolite bismethylmercury sulfide, thus exerting cytoprotection. In this study, we assessed the variation of RSS content in the rat brain and evaluated its relevance in sensitivity to MeHg. Analyses of fetal/juvenile rat brains showed low RSS levels in early developmental stages. Site-specific analysis of adult rat brains revealed that cerebellar RSS levels were lower than those of the hippocampus. Microscopically, RSS levels of the granular cell layer were lower than those of the molecular layer in the cerebellum. Thus, low RSS levels corresponded with age and site of the brain that is vulnerable to MeHg. Taken together with the finding that brain RSS were consumed during MeHg exposure, these results indicate that RSS is a factor that defines the specificity of MeHg vulnerability in the brain.

Neurobehavioural Changes and not Structural Changes Occur in Rat Fed with Cassava Products (Fufu, Garri and Tapioca Diet)

The ability of cassava products (fufu, garri and tapioca) to produce behavioral and structural changes in the brain of adult rats was examined. Forty adult male rats (N=40) were used for this study and the experiment was divided into two phases (N=20 each).Rat were trained in a Reach-To-Grasp Task for 6 weeks and Quantitative assessments using a reaching movement scale and reach-to-grasp success rate were carried out to determine baseline values. After which administration of the various cassava products was done. The 1st phase had the rats trained to perform the reach to grasp experiment before been fed with various cassava diet. In this phase the animals performed significantly worse than the controls when determining the average success rate in a reach-to-grasp experiment (baseline=72.6%, fufu diet= 30%, garri diet =47%, tapioca diet =59%). The 2nd phase had the rats trained simultaneously as they were being fed withvarious cassava diet. In this phase the animals also performed significantly worse than the controls when determining the average success rate in a reach-to-grasp experiment (fufu diet= 37.5%, garri diet =46.5%, tapioca diet =56.5%). The various movement of the rat was assessed using Tracker software (Video Analysis and Modeling tool, version 5.1.2) and the movement pattens were determined. The animals fed with Fufu shows the worst movement pattern indicating aiming impairment which may be as a result of structural changes in the m1 region of the cerebral cortex. The data obtained were analysed using ANOVA and there was significant difference (p &lt; 0.05) in the movement pattern. Histological observation showed no neuropathological changes in the motor cortex. The rats fed with cassava diets shows no observable changes in the structures and sizes of the neurons as compared with the control. Cassava products (Fufu, Garri and Tapioca) have been demonstrated to cause neurobehavioural and mild structural changes in the M1 region of the cerebral cortex.

Age-dependent alteration in metabolism of vitamin B6 , neurotransmitters, and amino acids after 4'-O-methylpyridoxine administration in rats.

4'-O-methylpyridoxine (MPN), a recognized antivitamin B6 compound, is a potentially poisonous substance found in Ginkgo biloba L. In this work, the effects of MPN on the metabolism of vitamin B6 , neurotransmitters, and amino acids were compared in the plasma and brain of young and adult rats under various administration times. Results showed that the contents of MPN residues in the plasma and brain of young rats were 12.72 and 14.76 µM higher than adult rats, respectively. Moreover, the levels of 5-hydroxytryptamine and dopamine in the brain of young rats have decreased by 13.78% and 7.19%, respectively, compared with the control group, at 2h after MPN administration. Furthermore, the principal component analysis revealed that MPN was an important contributor to the amino acid composition in the brain of young rats. These results suggest that age may lead to different toxic effects of MPN. PRACTICAL APPLICATION: 4'-O-methylpyridoxine is primarily responsible for poisoning due to overconsumption of Ginkgo biloba seeds. This study will provide an exploratory understanding of the age-dependent toxicity of 4'-O-methylpyridoxine.

Chitosan attenuated the neurotoxicity-induced titanium dioxide nanoparticles in brain of adult rats.

In the current study, we aimed to investigate the neurotoxic effect of oral titanium dioxide nanoparticles (TiO2 NPs) as well as the possible neuroprotective effect of carboxymethyl chitosan in adult rats for 14 days. The results revealed that TiO2 NPs inhibited the activity of the acetylcholine esterase enzyme and the levels of serotonin, dopamine, and norepinephrine neurotransmitters. Additionally, it induced neuro-oxidative stress and neuroinflammation via an elevation in MDA levels and IL-6, while GSH concentration, as well as GPx and GST activities, were decreased. TiO2 NPs induced neuronal apoptosis through upregulation of the expression of caspase-8 and -9 that was further confirmed by increasing caspases-3 and -8 proteins in the hippocampus, cerebral cortex, and cerebellum. The expression of the immediate-early gene BDNF was increased in response to TiO2 NPs, while that of Arc was reduced. Chitosan significantly attenuated the TiO2 NPs-induced neurotoxicity regarding AChE, serotonin, MDA, GSH, GPx, GST, IL-6, caspases-8, -9, and -3. Chitosan inhibited the expression of Arc and alleviated the effect of TiO2 NPs on BDNF expression. Collectively, TiO2 NPs induced neurotoxicity via their action on vital neuronal biomarkers that might in turn cause brain dysfunction. Despite the neuroprotection of chitosan, its inhibitory effect on Arc expression should be considered.

P.0418 Neonatal dexamethasone prevents an increase of pro-inflammatory cytokines expression after stress in the brains of adolescent and young adult rats

P.0418 Neonatal dexamethasone prevents an increase of pro-inflammatory cytokines expression after stress in the brains of adolescent and young adult rats

Immunohistochemical Characterization of Hepatic Nuclear Factor 4 Alpha Expression in the Choroid Plexus of the lateral and 4th ventricles of adult Male Rat Brain

The choroid plexus (CP) is present in brain ventricles. It is responsible for cerebrospinal fluid (CSF) secretion and various vital functions. Special proteins present in choroidal epithelium play important roles in CSF production and energy metabolism.This study aims to compare between the lateral and fourth ventricles CPs using hepatocyte nuclear factor 4 alpha (HNF4α), metabolism marker, to evaluate the functional activity of this tissue in the two regions.Ten adult male albino rats were used to study the histological features of the CPs and to study the functional activity by quantitative immunohistochemical labeling with HNF4α marker.The CP of the fourth ventricle had more functional activity than the CP of the lateral ventricle. A quantitative assessment of HNF4α using Aperio ImageScope Software Analysis showed that the lateral ventricle CP mean positivity 0.264 ± 0.083 pixel/micron² while the fourth ventricle CP have mean positivity 0.297 ± 0.043 pixel/micron². The immunohistochemical expression of marker in the fourth ventricle CP were significantly, P ≤ 0.05 higher than those in the lateral ventricle at P ≤ 0.05. Immunohistochemical detection of metabolism marker went along with findings of other histological and biochemical studies to define the CP as a highly dynamic structure with regional variations forming a continuum of one entity tissue capable of functional adaptation according to body needs.