Dopamine D4 receptor signaling in the rat paraventricular hypothalamic nucleus: Evidence of natural coupling involving immediate early gene induction and mitogen activated protein kinase phosphorylation
| Autor: | Michael W. Decker, Arthur L. Nikkel, Jorge D. Brioni, Stephani Otte, Brenda Martino, Robert B. Moreland, Pramila Bhatia, Robert S. Bitner, Andrew O. Stewart, Eve H. Barlow |
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| Rok vydání: | 2006 |
| Předmět: |
Male
medicine.medical_specialty Time Factors Receptor expression Gene Expression Cell Count Biology Piperazines Rats Sprague-Dawley Cellular and Molecular Neuroscience Dopamine receptor D1 Dopamine receptor D3 Dopamine Internal medicine Dopamine receptor D2 medicine Aminoacetonitrile Animals Drug Interactions Enzyme Inhibitors Phosphorylation Extracellular Signal-Regulated MAP Kinases Pharmacology Dose-Response Relationship Drug Receptors Dopamine D4 Dopaminergic Genes fos Immunohistochemistry Rats Endocrinology Dopamine receptor Benzamides Benzimidazoles Signal transduction Paraventricular Hypothalamic Nucleus Signal Transduction medicine.drug |
| Zdroj: | Neuropharmacology. 50:521-531 |
| ISSN: | 0028-3908 |
| Popis: | The dopamine D4 receptor has been investigated for its potential role in several CNS disorders, notably schizophrenia and more recently, erectile dysfunction. Whereas studies have investigated dopamine D4 receptor-mediated signaling in vitro, there have been few, if any, attempts to identify dopamine D4 receptor signal transduction pathways in vivo. In the present studies, the selective dopamine D4 agonist PD168077 induces c-Fos expression and extracellular signal regulated kinase (ERK) phosphorylation in the hypothalamic paraventricular nucleus (PVN), a site known to regulate proerectile activity. The selective dopamine D4 receptor antagonist A-381393 blocked both c-Fos expression and ERK1/2 phosphorylation produced by PD168077. In addition, PD168077-induced ERK1/2 phosphorylation was prevented by SL327, an inhibitor of ERK1/2 phosphorylation. Interestingly, treatment with A-381393 alone significantly reduced the amount of Fos immunoreactivity as compared to basal expression observed in vehicle-treated controls. Dopamine D4 receptor and c-Fos coexpression in the PVN was observed using double immunohistochemical labeling, suggesting that PD168077-induced signaling may result from direct dopamine D4 receptor activation. Our results demonstrate functional dopamine D4 receptor expression and natural coupling in the PVN linked to signal transduction pathways that include immediate early gene and MAP kinase activation. Further, the ability of the selective dopamine D4 antagonist A-381393 alone to reduce c-Fos expression below control levels may imply the presence of a tonic dopamine D4 receptor activation under basal conditions in vivo. These findings provide additional evidence that the PVN may be a site of dopamine D4 receptor-mediated proerectile activity. |
| Databáze: | OpenAIRE |
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