dizocilpine-maleate and pyrazolanthrone

Accumulating evidence indicates a pivotal role for neuroinflammation in ischemic and excitotoxic brain injury. Cytokine-induced neutrophil chemoattractant-1 (CINC-1) is a CXC chemokine implicated in the infiltration of inflammatory cells into the brain parenchyma. In this study, we investigated the effect of N-methyl-D-aspartate (NMDA)-induced neuronal injury on CINC-1 production in the organotypic cortico-striatal slice cultures. Treatment with 50 microM NMDA for 3 - 4 h caused devastating neuronal damage and increased CINC-1 production. Immunohistochemical analysis revealed that the CINC-1 immunoreactivity was predominantly detected in astrocytes. NMDA failed to induce CINC-1 production in enriched astrocyte cultures or neuron-depleted slice cultures, suggesting that NMDA acted on neuronal cells to induce astrocytic CINC-1 production. NMDA-induced CINC-1 mRNA expression was significantly inhibited by U0126, a mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK) kinase (MEK) inhibitor. These results suggest that NMDA-evoked neuronal injury induced astrocytic CINC-1 production via a MEK/ERK signaling pathway. Manipulation of this signaling pathway may serve as a target for suppressing neuroinflammation and, thereby, treating ischemic brain injury.

Topics: Animals; Anthracenes; Astrocytes; Butadienes; Cells, Cultured; Cerebral Cortex; Chemokine CXCL1; Corpus Striatum; Dizocilpine Maleate; Dose-Response Relationship, Drug; Enzyme Inhibitors; Enzyme-Linked Immunosorbent Assay; Imidazoles; Immunochemistry; Mitogen-Activated Protein Kinases; N-Methylaspartate; Neurons; Nitriles; Pyridines; Rats; Rats, Wistar; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors

The organotin trimethyltin (TMT) is known to cause neuronal degeneration in the central nervous system. A systemic injection of TMT produced neuronal damage in the cerebral frontal cortex of mice. To elucidate the mechanism(s) underlying the toxicity of TMT toward neurons, we prepared primary cultures of neurons from the cerebral cortex of mouse embryos for use in this study. Microscopic observations revealed that a continuous exposure to TMT produced neuronal damage with nuclear condensation in an incubation time-dependent manner up to 48 h. The neuronal damage induced by TMT was not blocked by N-methyl-D-aspartate receptor channel-blocker MK-801. The exposure to TMT produced an elevation of the phosphorylation level of c-Jun N-terminal kinase (JNK)(p46), but not JNK(p54), prior to neuronal death. Under the same conditions, a significant elevation was seen in the phosphorylation level of stress-activated protein kinase 1, which activates JNKs. Furthermore, TMT enhanced the expression and phosphorylation of c-Jun during a continuous exposure. The JNK inhibitor SP600125 was effective in significantly but only partially attenuating the TMT-induced nuclear condensation and accumulation of lactate dehydrogenase in the culture medium. Taken together, our data suggest that the neuronal damage induced by TMT was independent of excitotoxicity but that at least some of it was dependent on the JNK cascades in primary cultures of cortical neurons.

Topics: Animals; Anthracenes; Cell Survival; Cells, Cultured; Cerebral Cortex; Dizocilpine Maleate; Enzyme Activation; Fungicides, Industrial; Immunoblotting; Injections, Intraperitoneal; JNK Mitogen-Activated Protein Kinases; Male; MAP Kinase Kinase 4; Mice; Mice, Inbred Strains; N-Methylaspartate; Nerve Degeneration; Neurons; Phosphorylation; Time Factors; Trimethyltin Compounds

N-methyl-d-aspartate (NMDA) receptors and c-Jun N-terminal kinase (JNK) have been shown to be involved in morphine antinociceptive tolerance. However, whether chronic morphine-induced activation of the spinal JNK is NMDA receptor-dependent is unknown. The present study investigated the link between the spinal NMDA receptor NR2B subunit and the JNK activation during morphine antinociceptive tolerance in rats. Our results showed that chronic morphine treatment induced upregulation of the NR2B expression and activation of JNK in the spinal cord. Moreover, the increased NR2B-immunoreactivity (IR) and phosphorylated JNK-IR were observed mainly at the superficial dorsal horn laminae of the spinal cord; the spinal p-JNK was mainly expressed in astrocytes and NR2B in neurons. SP600125, a selective inhibitor of JNK, significantly attenuated morphine tolerance. MK-801, a noncompetitive NMDA receptor antagonist, not only suppressed morphine antinociceptive tolerance and the increase in NR2B, but also reduced the spinal JNK activation induced by chronic morphine treatment. These findings demonstrated for the first time that NMDA receptor-dependent activation of the spinal JNK contributes to morphine antinociceptive tolerance and that MK-801 attenuates morphine tolerance partly due to its inhibition on the spinal JNK activation.

Topics: Analgesics, Opioid; Animals; Anthracenes; Dizocilpine Maleate; Drug Tolerance; Enzyme Activation; JNK Mitogen-Activated Protein Kinases; Male; Morphine; Phosphorylation; Rats; Rats, Sprague-Dawley; Receptors, N-Methyl-D-Aspartate; Spinal Cord

EphBs receptors and ephrinBs ligands are present in the adult brain and peripheral tissue and play a critical role in modulating multiple aspects of physiology and pathophysiology. Ours and other studies have demonstrated that spinal ephrinBs/EphBs signaling was involved in the modulation of nociceptive information and central sensitization. However, the role of ephrinBs/EphBs signaling in peripheral sensitization is poorly understood. This study shows that intraplantar (i.pl.) injection of ephrinB1-Fc produces a dose- and time-dependent thermal and mechanical hyperalgesia and the increase of spinal Fos protein expression in mice, which can be partially prevented by pre-treatment with EphB1-Fc. EphrinB1-Fc-induced hyperalgesia is accompanied with the NMDA receptor-mediated increase of expression in peripheral and spinal phosphorylated mitogen-activated protein kinases (phospho-MAPKs) including p-p38, pERK and pJNK, and also is prevented or reversed by the inhibition of peripheral and spinal MAPKs. Furthermore, in formalin inflammation pain model, pre-inhibition of EphBs receptors by the injection of EphB1-Fc reduces pain behavior, which is accompanied by the decreased expression of peripheral p-p38, pERK and pJNK. These data provide evidence that ephrinBs may act as a prominent contributor to peripheral sensitization, and demonstrate that activation of peripheral ephrinBs/EphBs system induces hyperalgesia through a MAPKs-mediated mechanism.

Topics: Animals; Anthracenes; Butadienes; Dizocilpine Maleate; Ephrin-B1; Foot; Formaldehyde; Hot Temperature; Hyperalgesia; Injections, Spinal; Male; MAP Kinase Signaling System; Mice; Nitriles; p38 Mitogen-Activated Protein Kinases; Physical Stimulation; Protein Kinase Inhibitors; Proto-Oncogene Proteins c-fos; Receptors, Eph Family; Receptors, N-Methyl-D-Aspartate; Spinal Cord; Touch