The Activation of NMDA Receptor–ERK Pathway in the Central Amygdala is Required for the Expression of Morphine-Conditioned Place Preference in the Rat

Reinforcing effects of addictive drugs can be evaluated with the conditioned place preference (CPP) test which involves both the action of drugs and environmental cues. However, the encoded neural circuits and underlying signaling mechanism are not fully understood. In this study, we have used morphine-CPP model in the rat and characterized the role of N-methyl-d-aspartate (NMDA) receptor and the phosphorylation of extracellular signal-regulated kinase (ERK) in the central nuclei of amygdala (CeA) in the expression of morphine-induced CPP. We have found that morphine repeated pairing treatment causes a significant preference for compartment paired with morphine after 1 day or 7 days post-training, which is associated with increased ERK1/2 phosphorylation (p-ERK1/2, a measure of ERK activity) in the CeA. More than 80% of the positive p-ERK1/2 neurons express NMDA receptor subunit NR1 by double immunofluorescence studies. The infusion of either MEK inhibitor U0126 or NMDA receptor antagonist MK-801 in the CeA not only suppresses the activation of ERK1/2 in the CeA but also abolishes the expression of CPP. These results suggest that the activation of the NMDA receptor–ERK signaling pathway in the CeA is required for the expression of morphine-induced place preference in the rat.     

Glutamate–Dopamine Crosstalk in the Rat Prefrontal Cortex is Modulated by Alpha7 Nicotinic Receptors and Potentiated by PNU-120596

The aim of this study was to explore the modulation by α7 nicotinic receptors (nAChRs) of dopamine and glutamate release in the rat prefrontal cortex where these receptors are implicated in attentional processes and are therapeutic targets for cognitive deficits. The presence of presynaptic α7 nAChRs on glutamate terminals is supported by the ability of the subtype-selective agonist Compound A to evoke [³H]D-aspartate release from synaptosomes: This response was potentiated by the selective allosteric potentiator PNU-120596 and blocked by αbungarotoxin. Compound A also evoked dopamine overflow in the prefrontal cortex in vivo, and this was potentiated by PNU-120596. α7 nAChR-evoked [³H]dopamine release from tissue prisms in vitro was blocked by antagonists of NMDA and AMPA receptors. These data are consistent with a model in which α7 nAChRs present on glutamate terminals increase glutamate release that (1) contributes to presynaptic facilitation and synaptic plasticity and (2) co-ordinately enhances dopamine release from neighbouring boutons.     

Changes in the Permeability and Expression of Markers of the Structural and Functional Integrity of the Blood–Brain Barrier under Early Postnatal Hypoxia in vivo

Pathologies associated with perinatal exposure of the CNS to damaging factors, including hypoxia, are a serious problem. However, the mechanisms by which they influence the development of brain damage have been insufficiently studied. The purpose of this study is to analyze the BBB permeability and expression of markers of its structural and functional integrity in animals with hypoxia (rats subjected to hypoxia at the age of P7) at the early (1 hour after the hypoxia) and delayed (P28) periods of their development. In sections of the rat brains, we immunohistochemically evaluated the expression of HIF-1 and Rac1; the Evans blue dye content was measured by the photometric method in the brain homogenates. In animals subjected to hypoxia, BBB permeability increased, CD31 expression was reduced, RAC1 expression increased, HIF-1-positive cells were retained in the hippocampus mainly at the early stage of development; CD31 and RAC1 expression was suppressed during the delayed period of development. The most-pronounced brain damage at the age of P7 corresponds to changes in the structural and functional integrity and permeability of the BBB; the recovery of a neurological deficit and the permeability of the BBB (at the age of P28) under damage to the brain corresponds to the period of reparative angiogenesis, as well as manifestations of HIF-1 effects in endothelial cells and astrocytes in the cortex and limbic system.     

Lack of NMDA–AMPA interaction in antidepressant-like effect of CGP 37849, an antagonist of NMDA receptor,in the forced swim test

The NMDA receptor antagonist, CGP 37849-induced reduction in immobility time in the forced swim test in mice was not antagonized by pre-treatment with the AMPA receptor antagonist NBQX. This is the first demonstration of the antidepressant effect of the NMDA antagonist not being dependent on the AMPA transmission.     

Immunohistochemical Localization of α2-Adrenergic Receptors in the Neonatal Rat Cochlea and the Vestibular Labyrinth

The α₂-adrenergic receptors (α₂-ARs), which mediate physiological responses to noradrenaline and adrenaline, are encoded by three different genes but all are coupled to the G_i/G_o subfamily of G proteins. The present study investigated the localization of three subtypes, i.e., α_2a-, α_2b-, and α_2c-ARs, in cochlea and vestibular labyrinth in rat in the early postnatal period by immunohistochemistry. The results showed that α₂-ARs were widely distributed in regions, including the organ of Corti, spiral ganglion neurons, stria vascularis, crista ampullaris, Scarpa's ganglion, utricle, and Reissner's membrane. Furthermore, the cellular locations of α₂-ARs between different cell subtypes as well as receptor subtypes and different observed time points also had diversity. α_2a-AR mainly targeted to nuclei at postnatal ages (P)3. While at P(8), only ganglion neurons maintained this character whereas other cell types expressed α_2a-AR mainly in plasma membrane. The α_2b- and α_2c-ARs exhibited predominantly in plasma membrane. Compared with P(8), α_2c-AR was not present at stria vascularis at P(3). Overall, our observations indicated that there was region-specific regulation of α₂-ARs development in cochlea and vestibular labyrinth. In addition, the extensive expressions of α₂-ARs established a significant foundation for the exploration of the function of α₂-ARs in cochlea and vestibular labyrinth.     

Exposure–Response Relationship of the Synthetic Epothilone Sagopilone in a Peripheral Neurotoxicity Rat Model

Since peripheral sensory neuropathy is the major, clinically relevant side effect of sagopilone we investigated the general and peripheral neurotoxicity of sagopilone administered intravenously with different doses (1.2 and 2.4 mg/kg) and schedules in 48 Wistar rats and we performed in parallel a pharmacokinetic/pharmacodynamic (PK/PD) study. A trend toward a different peripheral neurotoxicity could be assessed after 2 weeks of treatment (bolus > 30-min infusion > 3-h infusion) with both doses of sagopilone. Although sagopilone concentrations in peripheral nerve tissue above 100 ng/g were associated with a reduction in nerve conduction velocity (NCV), a clear dose-dependence of this reduction on the level of systemic exposure to sagopilone was not observed. The PK/PD evaluation revealed no consistent effect of the infusion duration on serum PK parameters or the PD read-out NCV. Sagopilone concentrations in brain, sciatic nerve, liver, and kidney were higher after bolus compared to infusion, but there were no influence of infusion duration on these concentrations. No correlation between sagopilone concentrations in any organ/tissue with NCV changes was detected. This study evidences that the PD of sagopilone is not the main determinant of the onset and severity of sagopilone-induced peripheral neurotoxicity in the investigated clinically-relevant dose range, thus indicating that further investigation might identify neuronal-specific mechanisms of action able to drive a focused strategy to prevent peripheral neurotoxicity without reducing the anticancer effectiveness of the epothilones.     

Blockade of the NMDA and AMPA/kainate receptors in the dorsal raphe nucleus prevents the 5-HT₃ receptor agonist m-chlorophenylbiguanide-induced suppression of REM sleep in the rat

The effects of the selective 5-HT₃ receptor agonist m-chlorophenylbiguanide (m-CPBG), and of the NMDA (N-methyl-D-aspartate) and AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionate)/kainate antagonists AP-5 [(±)-2-amino-5-phosphono-pentanoic acid] and CNQX (6-cyano-7-nitroquinoxaline-2,3-dione), respectively, were studied in adult male Wistar rats implanted for chronic sleep recordings. The compounds were microinjected directly into the dorsal raphe nucleus (DRN) during the light period of the 12-h light/12-h dark cycle. Infusion of m-CPBG (2 and 4 mM) into the DRN induced a significant reduction of rapid-eye-movement sleep (REMS) and of the number of REM periods. Local infusion of AP-5 (0.5-1 mM) and CNQX (2 mM) significantly increased slow wave sleep (SWS). Pretreatment with AP-5 (0.5 mM) or CNQX (0.5 mM) antagonized the m-CPBG-induced suppression of REMS. It is proposed that the reduction of REMS after microinjection of m-CPBG into de DRN is related to the activation of glutamatergic interneurons that express the 5-HT₃ receptor and make synaptic contacts with serotonergic cells. The resultant increase of serotonin release at postsynaptic sites involved in the induction of REMS would provoke the suppression of the behavioral state. Our findings provide, in addition, new details concerning the pharmacology of DRN serotonergic neurons in the rat that may become relevant to the development of drugs for enhancing cortical and subcortical serotonergic neurotransmission.     

The Role of TNF-α and its Receptors in the Production of β-1,4 Galactosyltransferase I and V mRNAs by Rat Primary Astrocytes

Glycosylation is one of the most important post-translational modifications. It is clear that the single step of β-1,4-galactosylation is performed by a family of β-1, 4-galactosyltransferases (β-1,4-GalTs), and that each member of this family may play a distinct role in different tissues and cells. β-1,4-GalT I and V are involved in the biosynthesis of N-linked oligosaccharides. β-1,4-GalT I and V mRNAs are present in control astrocytes and affected by TNF-α and lipopolysaccharide (LPS) stimuli. In this study, we examined the regulatory mechanisms of tumor necrosis factor-α (TNF-α)-affected production of β-1,4-GalT I and V mRNAs. We show here that cultured astrocytes express TNF-α receptor 1 (TNFR1) and increased slightly after exposure to LPS. TNF-α and TNFR2 are not detected in control astrocytes and upregulated significantly with LPS stimulation and that activation of these receptors by TNF-α affects expressions of β-1,4-GalT I and V mRNAs. In addition, we observed that not only exogenous TNF-α but also TNF-α produced by astrocytes affected β-1,4-GalT I and V mRNAs production in astrocytes. These results suggest that an autocrine loop involving TNF-α contributes to the production of β-1,4-GalT I and V mRNA in response to inflammation. Chunlin Xia is the co-first author.     

Anacardic Acids from Cashew Nuts Prevent Behavioral Changes and Oxidative Stress Induced by Rotenone in a Rat Model of Parkinson’s Disease

Anacardic acids (AAs) are alkyl phenols mainly presenting in cashew nuts. The antioxidant effects of these compounds have been an area of interest in recent research, with findings suggesting potential therapeutic use for certain diseases. Nevertheless, none of these studies were performed in order to test the hypothesis of whether anacardic acids are capable of preventing behavioral changes and oxidative stress induced by the pesticide rotenone in experimental model of Parkinson’s disease. In our research, adult male rats were treated orally with AAs (1, 3, 10, 25, 50, or 100 mg/kg/day) 1 h before rotenone (3 mg/kg; s.c.) for five consecutive days. The behavioral testing strategies, including tests for general locomotor activity (open field), motor coordination (rotarod), and spatial memory performance (elevated T-maze), were carried out. Lipoperoxidation levels and total superoxide dismutase (t-SOD) activity, as well as cytoplasmic and mitochondrial SOD gene expression, were assessed in the substantia nigra (SN), striatum, and cerebral cortex. The results showed that AAs dose-dependently prevented the rotenone-induced learning and motor impairment from 10 mg/kg/day. AAs also precluded rotenone-induced lipoperoxidation in all doses, acting directly on the mitochondria, and improved the t-SOD activity in the doses 25–100 mg/kg/day. AAs per se (100 mg/kg/day) increased SOD gene expression and t-SOD activity. Our findings indicate that the oral administration of AAs prevents rotenone-induced behavioral changes and oxidative stress, in part due to a modulatory action on the mitochondria and SOD gene expression. These data suggest that AAs have promising neuroprotective action against degenerative changes in Parkinson’s disease.     

Changes in the Administrative Prevalence of Autism Spectrum Disorders: Contribution of Special Education and Health from 2002–2008

This study examined changes in the administrative prevalence of autism spectrum disorders (ASD) in Utah children from 2002 to 2008 by record source (school and health), age (four, six, and eight), and special education classification. Prevalence increased 100% with 1 in 77 children aged eight identified with ASD by 2008. Across study years and age groups rates were higher when health and school data were combined with a greater proportion of cases ascertained from health. The proportion of children with both a health ASD diagnosis and a special education autism classification did not significantly change. Most children with an ASD health diagnosis did not have an autism special education classification. Findings highlight the growing health and educational impact of ASD.     

A Lipoxin A<Subscript>4</Subscript> Analog Ameliorates Blood–Brain Barrier Dysfunction and Reduces MMP-9 Expression in a Rat Model of Focal Cerebral Ischemia–Reperfusion Injury

LXA₄ methyl ester (LXA₄ME), a lipoxin A₄ analog, reduces ischemic insult in the rat models of transient or permanent cerebral ischemic injury. We investigated whether LXA₄ME could ameliorate blood–brain barrier (BBB) dysfunction after stroke by reducing matrix metalloproteinase (MMP)-9 expression. Adult male rats were subjected to 2-h middle cerebral artery occlusion (MCAO) followed by 24-h reperfusion. Brain infarctions were detected by triphenyltetrazolium chloride (TTC) staining. BBB dysfunction was determined by examining brain edema and Evans Blue extravasation. Temporal expression of MMP-9 was determined by zymography and Western blot. The presence of tissue inhibitors of metalloproteinase-1 (TIMP-1) was also determined by Western blot in tissue protein sample. Brain edema and Evans Blue leakage were significantly reduced after stroke in the LXA₄ME group and were associated with reduced brain infarct volumes. MMP-9 activity and expression were inhibited by LXA₄ME after stroke. In addition, LXA₄ME significantly increased TIMP-1 protein levels. Our results indicate that LXA₄ME reduces brain injury by improving BBB function in a rat model of MCAO, and that a relationship exists between BBB permeability and MMP-9 expression following ischemic insult. Furthermore, these results suggest that LXA₄ME-mediated reduction of MMP-9 following stroke are attributed to increased TIMP-1 expression.     

Global–Local Precedence in the Perception of Facial Age and Emotional Expression by Children with Autism and Other Developmental Disabilities

Global information processing and perception of facial age and emotional expression was studied in children with autism, language disorders, mental retardation, and a clinical control group. Children were given a global–local task and asked to recognize age and emotion in human and canine faces. Children with autism made fewer global responses and more errors when recognizing human and canine emotions and canine age than children without autism. Significant relationships were found between global information processing and the recognition of human and canine emotions and canine age. Results are discussed with respect to the relationship between global information processing and face perception and neural structures underlying these abilities.     

Coenzyme Q10 Influences on the Levels of TNF-α and IL-10 and the Ratio of Bax/Bcl2 in a Menopausal Rat Model Following Lumbar Spinal Cord Injury

The roles of the immune response and apoptosis as potential mediators of secondary damage in spinal cord injury (SCI) are being investigated. Research is also being done to determine the effects of female gonadal steroids, which decrease during menopause, and antioxidants, such as coenzyme Q10 (CoQ10) on SCI. We hypothesized that in the absence of female gonadal steroids, which provide protection following an SCI, CoQ10 could modulate the expression of cytokines, such as tumor necrosis factor (TNF)-α and interleukin (IL)-10, besides aquaporin-4 (AQP4) water channels in the CNS, which participate in neuroinflammation, as well as the Bax and Bcl2 proteins that are involved in apoptosis at the site of injury. The spinal cord was compressed at the level of the T10 vertebrae and rats were treated by 10 mg/kg/day CoQ10 for 3 weeks after surgery. The TNF-α and IL-10 expressions were studied using an ELISA. Western blot was used to investigate the Bax/Bcl-2 ratio, AQP4. The level of TNF-α significantly decreased following the administration of CoQ10 compared with the level of IL-10. When the treatment group was compared with the OVX-SCI group, the ratio of Bax/Bcl2 significantly decreased in the groups (P?<?0.01). Based on our findings, CoQ10 could be used to compensate for the absence of the neuroprotection effects provided by female gonadal steroids via reducing the inappropriate effects of the two main pathways of secondary damage in SCI apoptosis.