Aromatic L-amino acid decarboxylase is modulated by D1 dopamine receptors in rat retina
| Autor: | Zvani L. Rossetti, C. P. Silvia, Dimitrij Krajnc, Norton H. Neff, Maria Hadjiconstantinou |
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| Rok vydání: | 1990 |
| Předmět: |
Agonist
Male medicine.medical_specialty Light medicine.drug_class Biology Biochemistry Retina Receptors Dopamine Cellular and Molecular Neuroscience chemistry.chemical_compound Quinpirole Dopamine receptor D1 Dopamine Internal medicine medicine Animals Aromatic L-amino acid decarboxylase SCH-23390 Dose-Response Relationship Drug Receptors Dopamine D1 Rats Inbred Strains Benzazepines Rats Apomorphine Kinetics Endocrinology chemistry Dopamine receptor Aromatic-L-Amino-Acid Decarboxylases Dopamine Antagonists 2 3 4 5-Tetrahydro-7 8-dihydroxy-1-phenyl-1H-3-benzazepine medicine.drug |
| Zdroj: | Journal of neurochemistry. 54(3) |
| ISSN: | 0022-3042 |
| Popis: | Aromatic L-amino acid decarboxylase (AAAD) activity of rat retina increases when animals are placed in a lighted environment from the dark. The increase of activity can be inhibited by administering the selective dopamine D1 receptor agonist SKF 38393, but not the selective D2 agonist quinpirole, or apomorphine. Conversely, in the dark, enzyme activity can be enhanced by administering the selective D1 antagonist SCH 23390 or haloperidol, but not the selective D2 antagonist (-)-sulpiride. Furthermore, in animals exposed to room light for 3 h, the D1 agonist SKF 38393 reduced retinal AAAD activity, and this effect was prevented by prior administration of SCH 23390. In contrast, quinpirole had little or no effect when administered to animals in the light. Kinetic analysis indicated that the apparent Vmax for the enzyme increases with little change in the apparent Km for the substrate 3,4-dihydroxyphenylalanine or the cofactor pyridoxal-5'-phosphate. We suggest that dopamine released in the dark tonically occupies D1 receptors and suppresses AAAD activity. When the room light is turned on, D1 receptors are vacated and selective D1 agonists can either prevent the rise of AAAD or reverse light-enhanced AAAD activity. |
| Databáze: | OpenAIRE |
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