Different Regions Of Mouse Brain Research Articles

A viscoelastic analysis of the P56 mouse brain under large-deformation dynamic indentation.

We present the first mechanical characterization of the viscoelastic response for different regions of mouse brain. Force-relaxation tests are performed under large strain dynamic micro-indentation, and viscoelastic models are used subsequently, providing time-dependent mechanical properties of brain tissue under loading conditions comparable to what is experienced in TBI. The unique mechanical properties of different brain regions are highlighted, with substantial variations in the viscoelastic properties and damping ratio of each region. Cortex and pons were the stiffest regions, while the thalamus and medulla were most compliant. The cerebellum and thalamus had highest damping ratio values and those of the medulla were lowest. The reported material parameters can be implemented into finite element computer models of the mouse to investigate the effects of trauma on individual brain regions.

Heat Shock Protein 90 Regulates μ‐Opioid Receptor Signaling In Vitro and in Different Regions of Mouse Brain

Heat shock protein 90 (Hsp90) is a ubiquitous and highly expressed regulator for various signaling pathways and proteins. Only 2 previous studies suggested that Hsp90 might be involved in the regulation of opioid receptor signaling, which is one of the primary targets for drug discovery for chronic pain. This study was designed to determine the regulatory activities of Hsp90 on μ‐opioid receptor (MOR) signaling in various types of MOR expressing cells and in mouse brain. MOR expressing CHO, HEK, U2OS, and SH‐SY5Y neuroblastoma cells were treated with an Hsp90 specific inhibitor (17‐AAG) for 24 hrs followed by treatment with the MOR full agonist DAMGO. The expression and activation of signaling proteins was investigated by Western blot. We found that the expression of MOR, βarrestin2, and Akt was reduced in some cell types by inhibiting Hsp90. In contrast, the expression of Hsp70 was increased by the treatment of 17‐AAG in all cell types, as expected. The activation of ERK MAPK was also altered by Hsp90 inhibition in a cell context dependent manner – whether increasing DAMGO stimulated activation, increasing the baseline, or blunting activation. The strongly context dependent nature of Hsp90 regulation indicated that we would need to determine the role of Hsp90 in regulating the MOR in vivo. We thus injected CD‐1 mice intracerebroventricularly with 17‐AAG for 24 hrs, followed by injection of vehicle or DAMGO into the brain. Interestingly, we found an increased ERK signaling baseline and abolished DAMGO induction in the periaqueductal grey, along with increased Hsp70 expression. Preliminary results in the brain stem suggest that ERK MAPK activation in response to DAMGO is abolished by 17‐AAG, without increasing the baseline. Furthermore, 17‐AAG treatment showed a modest decrease on the acute anti‐nociceptive tail‐flick response to DAMGO, and increased urine and feces output after naloxone precipitated withdrawal in models of acute and chronic dependence. These findings demonstrate that Hsp90 has a strong regulatory role in MOR signaling both in vitro and in vivo, and suggest that Hsp90 activators or other modulators could be potentially used as a co‐therapy for improving the therapeutic index of opioid drugs.Support or Funding InformationWork supported by institutional startup funds from the University of Arizona, along with an internal UNE Mini‐Grant and a Pilot Grant from a UNE Centers for Biomedical Research and Excellent (COBRE) grant (Ian Meng PI, #P20GM103643).

Visual Circuits: Mouse Retina No Longer a Level Playing Field

Unlike humans, monkeys, or carnivores, mice are thought to lack a retinal subregion devoted to high-resolution vision; systematic analysis has now shown that mice encode visual space non-uniformly, increasing their spatial sampling of the binocular visual field.

Glutamatergic and GABAergic TCA Cycle and Neurotransmitter Cycling Fluxes in Different Regions of Mouse Brain

The (13)C nuclear magnetic resonance (NMR) studies together with the infusion of (13)C-labeled substrates in rats and humans have provided important insight into brain energy metabolism. In the present study, we have extended a three-compartment metabolic model in mouse to investigate glutamatergic and GABAergic tricarboxylic acid (TCA) cycle and neurotransmitter cycle fluxes across different regions of the brain. The (13)C turnover of amino acids from [1,6-(13)C2]glucose was monitored ex vivo using (1)H-[(13)C]-NMR spectroscopy. The astroglial glutamate pool size, one of the important parameters of the model, was estimated by a short infusion of [2-(13)C]acetate. The ratio Vcyc/VTCA was calculated from the steady-state acetate experiment. The (13)C turnover curves of [4-(13)C]/[3-(13)C]glutamate, [4-(13)C]glutamine, [2-(13)C]/[3-(13)C]GABA, and [3-(13)C]aspartate from [1,6-(13)C2]glucose were analyzed using a three-compartment metabolic model to estimate the rates of the TCA cycle and neurotransmitter cycle associated with glutamatergic and GABAergic neurons. The glutamatergic TCA cycle rate was found to be highest in the cerebral cortex (0.91 ± 0.05 μmol/g per minute) and least in the hippocampal region (0.64 ± 0.07 μmol/g per minute) of the mouse brain. In contrast, the GABAergic TCA cycle flux was found to be highest in the thalamus-hypothalamus (0.28 ± 0.01 μmol/g per minute) and least in the cerebral cortex (0.24 ± 0.02 μmol/g per minute). These findings indicate that the energetics of excitatory and inhibitory function is distinct across the mouse brain.

Alterations in Phosphorylated CREB Expression in Different Brain Regions following Short- and Long-Term Morphine Exposure: Relationship to Food Intake

Background. Activation of the cyclic adenosine monophosphate (cAMP)/phosphorylated CREB (P-CREB) system in different brain regions has been implicated in mediating opioid tolerance and dependence, while alteration of this system in the lateral hypothalamus (LH) has been suggested to have a role in food intake and body weight. Methods. Given that opioids regulate food intake, we measured P-CREB in different brain regions in mice exposed to morphine treatments designed to induce different degrees of tolerance and dependence. Results. We found that a single morphine injection or daily morphine injections for 8 days did not influence P-CREB levels, while the escalating dose of morphine regimen raised P-CREB levels only in the ventral tegmental area (VTA). Chronic morphine pellet implantation for 7 days raised P-CREB levels in the LH, VTA, and dorsomedial nucleus of the hypothalamus (DM) but not in the nucleus accumbens and amygdala. Increased P-CREB levels in LH, VTA, and DM following 7-day treatment with morphine pellets and increased P-CREB levels in the VTA following escalating doses of morphine were associated with decreased food intake and body weight. Conclusion. The morphine regulation of P-CREB may explain some of the physiological sequelae of opioid exposure including altered food intake and body weight.

Nucleus Accumbens 1, a Pox virus and Zinc finger/Bric-a-brac Tramtrack Broad protein binds to TAR DNA-binding protein 43 and has a potential role in Amyotrophic Lateral Sclerosis

Protein degradation is a critical component of cellular maintenance. The intracellular translocation and targeting of the Ubiquitin Proteasome System (UPS) differentially coordinates a protein’s half-life and thereby its function. Nucleus Accumbens 1 (NAC1), a member of the Pox virus and Zinc finger/Bric-a-brac Tramtrack Broad complex (POZ/BTB) family of proteins, participates in the coordinated proteolysis of synaptic proteins by mediating recruitment of the UPS to dendritic spines. Here we report a novel interaction between NAC1 and TAR DNA-binding protein 43 (TDP-43), a protein identified as the primary component of ubiquitinated protein aggregates found in patients with Amyotrophic Lateral Sclerosis (ALS). In vitro translated full-length TDP-43 associated with both the POZ/BTB domain and the non-POZ/BTB domain of NAC1 in GST pulldown assays. Other POZ/BTB proteins (including zinc finger POZ/BTB proteins and atypical POZ/BTB proteins) showed weak interactions with TDP-43. In addition, NAC1 and TDP-43 were present in the same immunocomplexes in different regions of mouse brain and spinal cord. In primary spinal cord cultures, TDP-43 expression was mainly nuclear, whereas NAC1 was both nuclear and cytoplasmic. In order to mimic ALS-like toxicity in the spinal cord culture system, we elevated extracellular glutamate levels resulting in the selective loss of motor neurons. Using this model, it was found that glutamate toxicity elicited a dose-dependent translocation of TDP-43 out of the nucleus of cholinergic neurons and increased the co-localization of NAC1 and TDP-43. These findings suggest that NAC1 may function to link TDP-43 to the proteasome; thereby, facilitating the post-translational modifications of TDP-43 that lead to the development of ALS.

Differential regional expression patterns of α-synuclein, TNF-α, and IL-1β; and variable status of dopaminergic neurotoxicity in mouse brain after Paraquat treatment

BackgroundParaquat (1, 1-dimethyl-4, 4-bipyridium dichloride; PQ) causes neurotoxicity, especially dopaminergic neurotoxicity, and is a supposed risk factor for Parkinson's disease (PD). However, the cellular and molecular mechanisms of PQ-induced neurodegeneration are far from clear. Previous studies have shown that PQ induces neuroinflammation and dopaminergic cell loss, but the prime cause of those events is still in debate.MethodsWe examined the neuropathological effects of PQ not only in substantia nigra (SN) but also in frontal cortex (FC) and hippocampus of the progressive mouse (adult Swiss albino) model of PD-like neurodegeneration, using immunohistochemistry, western blots, and histological and biochemical analyses.ResultsPQ caused differential patterns of changes in cellular morphology and expression of proteins related to PD and neuroinflammation in the three regions examined (SN, FC and hippocampus). Coincident with behavioral impairment and brain-specific ROS generation, there was differential immunolocalization and decreased expression levels of tyrosine hydroxylase (TH) in the three regions, whereas α-synuclein immunopositivity increased in hippocampus, increased in FC and decreased in SN. PQ-induced neuroinflammation was characterized by area-specific changes in localization and appearances of microglial cells with or without activation and increment in expression patterns of tumor necrosis factor-α in the three regions of mouse brain. Expression of interleukin-1β was increased in FC and hippocampus but not significantly changed in SN.ConclusionThe present study demonstrates that PQ induces ROS production and differential α-synuclein expression that promotes neuroinflammation in microglia-dependent or -independent manners, and produces different patterns of dopaminergic neurotoxicity in three different regions of mouse brain.

Non-Nucleoside Reverse Transcriptase Inhibitors Efavirenz and Nevirapine Inhibit Cytochrome C Oxidase in Mouse Brain Regions

The highly active antiretroviral therapy completely changed the clinical evolution of HIV infection, reducing the morbidity and mortality among human immunodeficiency virus (HIV)-1 infected patients. Therefore, in the present study we evaluated the effect of chronic efavirenz (EFV) and nevirapine (NVP) administration on mitochondrial respiratory chain complexes activities (I, II, II-III, IV) in different brain regions of mice. Mice were orally administered via gavage with EFV 10 mg/kg, NVP 3.3 mg/kg or vehicle (controls) once a day for 36 days. We observed that the complex IV activity was inhibited by both EFV and NVP in cerebral cortex, striatum and hippocampus of mice, but not in cerebellum, as compared to control group. In contrast, chronic EFV and NVP administration did not alter complexes I, II and II-III. We speculated that brain energy metabolism dysfunction could be involved in the CNS-related adverse effects.

GABA and Dopamine Release from Different Brain Regions in Mice with Chronic Exposure to Organophosphate Methamidophos

Organophosphates such as methamidophos, usually used in the agricultural field, have harmful effects on humans. Exposures to insecticides has been associated with many disorders, including damage to the central and peripheral nervous system. Chronic exposure to organophosphates may lead to persistent neurological and neurobehavioral effects. This study was conducted to determine the effect of methamidophos on [3H]-dopamine (DA) and gamma aminobutyric acid (GABA) release from different brain regions after chronic exposure to it for 3, 6 or 9 months. After a six-month methamidophos treatment, the mice showed high susceptibility to convulsive seizures and a reduction in stimulated gamma aminobutyric acid release from the cerebral cortex and hippocampal slices, whereas stimulated (DA) release was slightly decreased from the striatum after three months of methamidophos exposure. The results indicate changes in gamma aminobutyric acid and dopamine neurotransmission, suggesting a specific neuronal damage.

Mass spectrometric quantification of MIF-1 in mouse brain by multiple reaction monitoring

MIF-1 (Pro-Leu-Gly-NH 2) has potent therapeutic effects in depression and Parkinson's disease, but its CNS sites of production are not yet clear. In this study, the concentration of MIF-1 in different brain regions was measured by the multiple reaction monitoring technique on a 4000 QTRAP mass spectrometer. The limit of quantification was 300 fg of MIF-1, and limit of detection was 60 fg. The low molecular weight fractions of tissue homogenates from different regions of mouse brain were analyzed. The concentration of MIF-1 ranged from 22 ± 3 fg/μg protein in cerebral cortex to 930 ± 60 fg/μg protein in the hypothalamus. Moderate concentrations were also detected in all other regions tested, including the striatum, thalamus, and hippocampus. By incubation of stable isotope-labeled oxytocin with tissue preparations, it was also confirmed that oxytocin at least partially contributed to the production of MIF-1 in the hypothalamus by action of peptidases. Regional differences were also found. The results are the first to show the ultrasensitive quantification of MIF-1 in different brain regions, and support the neuromodulatory actions of MIF-1 in the striatum.

Effects of acute and chronic administration of MK-801 on c-Fos protein expression in mice brain regions implicated in schizophrenia with or without clozapine

This study investigated the effects of acute and chronic administration of the non-competitive NMDA receptor antagonists MK-801 on c-Fos protein expression in different brain regions of mice with or without clozapine. MK-801 (0.6 mg/kg) acute administration produced a significant increase in the expression of c-Fos protein in the layers III–IV of posterior cingulate and retrosplenial (PC/RS) cortex, which was consistent with the previous reports. Moreover, we presented a new finding that MK-801 (0.6 mg/kg) chronic administration for 8 days produced a significant increase of c-Fos protein expression in the PC/RS cortex, prefrontal cortex (PFC) and hypothalamus of mice. Among that, c-Fos protein expression in the PC/RS cortex of mice was most significant. Compared to acute administration, we found that MK-801 chronic administration significantly increased the expression of c-Fos protein in the PC/RS cortex, PFC and hypothalamus. Furthermore, pretreatment of mice with clozapine significantly decreased the expression of c-Fos protein induced by MK-801 acute and chronic administration. These results suggest that c-Fos protein, the marker of neuronal activation, might play an important role in the chronic pathophysiological process of schizophrenic model induced by NMDA receptor antagonist.

Dissociation of functional status from accrual of CML and RAGE in the aged mouse brain

The objectives of this study were: (i) to identify regions of the aged mouse brain in which advanced glycation end-products (AGEs) were increased, and (ii) assess the functional significance of AGEs by determining the extent to which they could predict age-related brain dysfunction. Densitometric analyses of immunoblots for N epsilon-(carboxymethyl)lysine (CML), a predominant AGE, and receptor for AGE (RAGE), were performed in different brain regions of mice aged 8 or 25 months. The 25-month-old mice were tested for ability to perform on tests of cognitive and psychomotor function prior to assessment of CML or RAGE, to determine if immunostaining results could predict functional impairment among the older mice. The amounts of CML increased with age in cortex, hippocampus, striatum, and midbrain, but were unchanged in the brainstem and cerebellum. Increases in RAGE were evident in all brain regions but the hippocampus, and were not linked to increased amounts of CML. Different statistical approaches each failed to reveal any strong association between the degree of age-related functional impairment among individual mice and amounts of CML or RAGE in any particular region of the brain. The findings from this study suggest that accrual of CML and expression of RAGE in different brain regions are time-related phenomena that do not account for individual differences in brain aging or cognitive decline.

Comparative Analysis of Selenocysteine Machinery and Selenoproteome Gene Expression in Mouse Brain Identifies Neurons as Key Functional Sites of Selenium in Mammals

Although dietary selenium (Se) deficiency results in phenotypes associated with selenoprotein depletion in various organs, the brain is protected from Se loss. To address the basis for the critical role of Se in brain function, we carried out comparative gene expression analyses for the complete selenoproteome and associated biosynthetic factors. Using the Allen Brain Atlas, we evaluated 159 regions of adult mouse brain and provided experimental analyses of selected selenoproteins. All 24 selenoprotein mRNAs were expressed in the mouse brain. Most strikingly, neurons in olfactory bulb, hippocampus, cerebral cortex, and cerebellar cortex were exceptionally rich in selenoprotein gene expression, in particular in GPx4, SelK, SelM, SelW, and Sep15. Over half of the selenoprotein genes were also expressed in the choroid plexus. A unique expression pattern was observed for one of the highly expressed selenoprotein genes, SelP, which we suggest to provide neurons with Se. Cluster analysis of the expression data linked certain selenoproteins and selenocysteine machinery genes and suggested functional linkages among selenoproteins, such as that between SelM and Sep15. Overall, this study suggests that the main functions of selenium in mammals are confined to certain neurons in the brain.

Gene expression in mouse brain following chronic hypoxia: role of sarcospan in glial cell death

Hypoxia is a hallmark of respiratory, neurological, or hematological diseases as well as life at high altitude. For example, chronic constant hypoxia (CCH) occurs in chronic lung diseases or at high altitude, whereas chronic intermittent hypoxia (CIH) occurs in diseases such as sleep apnea or sickle cell disease. Despite the fact that such conditions are frequent, the cellular and molecular mechanisms underlying the effect of hypoxia, whether constant or intermittent, are not well understood. In this study, we first determined the effect of CCH and CIH on global gene expression in different regions of mouse brain using microarrays and then investigated the biological role of genes of interest. We found that: 1) in the cortical region, the expression level of 80 genes was significantly altered by CIH (16 up- and 64 downregulated), and this number increased to 137 genes following CCH (34 up- and 103 downregulated); 2) a similar number of gene alterations was identified in the hippocampal area, and the majority of the changes in this region were upregulations; 3) two genes (Sspn and Ttc27) were downregulated in both brain regions and following both treatments; and 4) RNA interference-mediated knockdown of Sspn increased cell death in hypoxia in a cell culture system. We conclude that CIH or CCH induced significant and distinguishable alterations in gene expression in cortex and hippocampus and that Sspn seems to play a critical role in inducing cell death under hypoxic conditions.

Limbic structures are prone to age‐related impairments in proteasome activity and neuronal ubiquitinated inclusions in SAMP10 mouse: a model of cerebral degeneration

Neurodegenerative diseases are characterized by ubiquitinated inclusions in selective brain regions. Here we investigated whether the dysfunction of the ubiquitin proteasome system might be involved in the pathogenesis and regional selectivity of neuronal ubiquitinated inclusions using the SAMP10 strain of mouse, an inbred model of age-related cerebral degeneration. By comparing SAMP10 mice at various ages with SAMR1 and C57BL mice as normal brain ageing controls, we studied morphological features and distribution of inclusions. We measured tissue proteasome activity in different brain regions of mice at various ages by fluorogenic substrate assays. We induced inclusions in cultured neurones by inhibiting the proteasome and analysed changes in the dendritic morphology. Inclusions were formed in association with lipofuscin in neuronal perikarya and occurred most frequently in the limbic-related forebrain structures. There were sparse inclusion-bearing neurones in the non-limbic forebrain. In aged SAMR1 and C57BL, there were far fewer inclusions in the limbic-related forebrain than in aged SAMP10. The proteasome activity in the limbic-related forebrain decreased much more rapidly and remarkably upon ageing (26% activity was detected in 17-month-old compared with 3-month-old mice) in SAMP10 than in SAMR1. The proteasome activity in the non-limbic forebrain did not change significantly with advancing age in either SAMP10 or SAMR1. Proteasomal inhibition enhanced the formation of ubiquitinated inclusions in cultured neurones. Neurones bearing inclusions had shortened neurites. We propose that the regional selectivity of proteasomal impairment is causally related to the selectivity of inclusion formation and associated dendritic degeneration in neurones of ageing SAMP10 mice.

Volatile of alkyd varnish inhibits the expression of neuronal growth associated protein-43 in mice

Background Studies have demonstrated that coating materials used commonly in the interior decoration contain volatile of alkyd varnish, which has obvious effects on the structure of endothelial cells of respiratory tract. Objective To observe the effects of volatile of alkyd varnish in the decoration materials on the expression of neuronal growth associated protein-43 (GAP-43) in mice, and to analyze the influencing mechanism of interior environmental pollutants for brain mechanism. Design A randomized grouping and controlled experiment. Setting College of Life Science, Liaoning Normal University. Materials This study was carried out in the College of Life Science, Liaoning Normal University between February and December 2006. Twenty one-month-old Kunming mice, weighing (20±2)g, male and female in half, were involved in this study. The involved mice were divided into 2 groups by random lot method: chronic poisoning group ( n =10) and control group ( n =10). Alkyd varnish used commonly for house decoration was purchased from Furnishing World of Liberation Plaza of Dalian City. Alkyd varnish used commonly for house decoration was purchased from Furnishing World of Liberation Plaza of Dalian City. Rabbit GAP-43 polyclonal antibody, ratβ-actin monoclonal antibody, goat anti-rat IgG-HRP and goat ant-rabbit IgG-HRP were purchased from Boster Company (Wuhan). ECL was purchased from Amersham Company (Britain), other related reagents were all purchased from Sigma Company and Promega Company (USA). All the other reagents were home-made analytical pure. Methods ▪Poisoning test The mice were poisoned by static inhalation poisoning method. Mice in the chronic poisoning group were placed in the 0.024 m 3 poisoning cabinet. Alkyd varnish (8 g, 3-time dosage of house decoration) was daily spread once on a 40 cm×21 cm kraft paper evenly. Mice were poisoned for 14 hours within 3 weeks successively. Mice in the control group were placed in the same environment without alkyd varnish, and the poisoning method was the same as that of chronic poisoning group. ▪Experimental evaluation: content of protein in the cortex, cerebellum and hippocampus of mice was measured separately by Bradford method. GAP-43 expression in the hippocampus and cortex was observed separately by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Main Outcome Measures Content of protein and expression of GAP-43 in different brain regions of mice. Results Twenty mice were involved in the final analysis. ▪Content of protein in the cerebellum and hippocampus of mice in the chronic poisoning group was decreased a little, separately ( P > 0.05). ▪ GAP-43 expression in the hippocampus of mice of the chronic poisoning group was significantly lower than that of the control group( P < 0.05). Conclusion Long-term action of volatile of alkyd varnish can inhibit the brain functions of mice by depressing the GAP-43 expression in hippocampus of mice.

Changes in AMPA subunit expression in the mouse brain after chronic treatment with the antidepressant maprotiline: a link between noradrenergic and glutamatergic function?

Potentiation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor function has been proposed as being useful in the treatment of depression, but thus far, little is known about the possible changes in AMPA receptor expression in the brain, after antidepressant treatment. The present study was carried out to study the expression of AMPA receptor subunits in different brain regions of mice that had been chronically injected with maprotiline. The latter is a modified tricyclic antidepressant that functions as a noradrenaline uptake inhibitor. Daily intraperitoneal injection with 10 mg/kg maprotiline for 30 days resulted in significantly increased GluR1 and GluR2/3 subunit expression in the nucleus accumbens and dorsal striatum as detected by immunohistochemistry; and significantly increased GluR1 and GluR2/3 expression in the hippocampus, as demonstrated by Western blot analysis. No change, or a decrease in GluR2 expression was detected in all the brain regions by both immunohistochemistry and Western blots. The increase in GluR1 and GluR2/3, but no increase in GluR2 subunits suggests that there could be an increase in calcium permeability of AMPA receptors in limbic/striatal brain regions after maprotiline treatment. This could lead to increased synaptic activity or plasticity in the hippocampus and striatum, and may underlie the therapeutic effect of maprotline, and possibly, other antidepressant drugs.

Induction of the immediate early genes egr-1 and c-fos by methamphetamine in mouse brain

Methamphetamine (METH) is one of the most commonly abused psychostimulant, and is known to induce dopaminergic neurotoxicity by generating oxidative stress and free radicals. In the present study we investigated the effects of METH on egr-1 and c-fos immediate early gene induction in different regions of mouse brain, at different doses and different time courses. We also measured the tissue levels of monoamines in order to correlate their changes with gene expression. A single injection of METH (40 mg/kg) significantly increased egr-1 and c-fos mRNA expression within 30 min in frontal cortex, nucleus accumbens, caudate putamen, septum and CA1 region of hippocampus. Time course studies showed that in most cases, both genes were expressed within 30 min and decreased after 60 min. METH produced a significant decrease in striatal dopamine level, reaching a very low level after 24 h. Striatal serotonin level significantly increased and returned to control levels after 2 h. These data show that METH induced egr-1 and c-fos mRNA expression in selective brain areas, which correlated with an alteration in monoamines.

Differential expression of cellular prion protein in mouse brain as detected with multiple anti-PrP monoclonal antibodies

The normal cellular prion protein (PrP C) plays an essential role in the development of prion diseases. Indirect evidence has suggested that different PrP C glycoforms may be expressed in different brain regions and perform distinct functions. However, due to a lack of monoclonal antibodies (Mabs) that are specific for mouse PrP C, the expression of PrP C in the mouse brain has not been studied in great detail. We used Mabs specific for either the N-terminus or the C-terminus of the mouse PrP C to study its expression in the mouse brain by immunoblotting and immunohistochemistry. Immunoblotting studies demonstrated that the expression of PrP C differed quantitatively as well as qualitatively in different regions of the brain. The anti-C-terminus Mabs reacted with all three molecular weight bands of PrP C; the anti-N-terminus Mabs only reacted with the 39–42 kDa PrP C. The results from immunohistochemical staining revealed the spatial distribution of PrP C in the mouse brain, which were consistent with that from immunoblotting. Although expression of PrP C has been reported to be required for long-term survival of Purkinje cells, we were unable to detect PrP C in the Purkinje cell layer in the cerebellum with multiple anti-PrP Mabs. Our findings suggest that PrP C variants, i.e. various glycoforms and truncated forms, might be specifically expressed in different regions of mouse brain and might have different functions.

Acute ibogaine injection induces expression of the immediate early genes, egr-1 and c- fos, in mouse brain

The aim of the present study was to evaluate if an acute injection of ibogaine (IBO) induces immediate early gene expression in different regions of mouse brain. Adult male C57 mice received a single injection of IBO and were perfused transcardially with 1% paraformaldehyde 30 min after the drug administration. A single injection of IBO produced a significant increase of egr-1 messenger RNA induction in nucleus accumbens (NAc), caudate–putamen (CPu), frontal cortex (FCx), septum, dentate gyrus (DG) and CA3 region of hippocampus, whereas c- fos gene was induced in CPu, FCx, DG, septum and CA1 region of hippocampus. This gene expression may be due, in part, to the stimulant properties of IBO, as we found with other psychostimulants.