Agonist-induced μ opioid receptor phosphorylation and functional desensitization in rat thalamus
| Autor: | Hong Bing Deng, Wei Guang, Hongyan Wang, Jia Bei Wang, Yunkai Yu |
|---|---|
| Rok vydání: | 2001 |
| Předmět: |
Male
Narcotics Agonist medicine.medical_specialty Time Factors medicine.drug_class Narcotic Antagonists Receptors Opioid mu Striatum Biology Drug Administration Schedule Rats Sprague-Dawley Adenylyl cyclase chemistry.chemical_compound Organ Culture Techniques Thalamus Opioid receptor Cerebellum Internal medicine medicine Animals Phosphorylation Receptor Molecular Biology Dose-Response Relationship Drug Morphine Naloxone General Neuroscience Drug Tolerance Enkephalin Ala(2)-MePhe(4)-Gly(5) Immunohistochemistry Rats Analgesics Opioid Neostriatum DAMGO Endocrinology chemistry Neurology (clinical) μ-opioid receptor Adenylyl Cyclases Developmental Biology |
| Zdroj: | Brain Research. 898:204-214 |
| ISSN: | 0006-8993 |
| DOI: | 10.1016/s0006-8993(01)02179-5 |
| Popis: | By metabolically labeling tissue slices from striatum and thalamus with [32P]orthophosphoric acid and immunoprecipitating the receptor with mu receptor-specific antiserum, we found that the endogenous mu receptor in the brain tissue did undergo phosphorylation. The phosphorylation occurred at basal level (no drug treatment) and was enhanced with DAMGO-treatment. The enhancement of the phosphorylation was blocked by naloxone. Morphine stimulation also increased the phosphorylation, but the amount of enhancement was less than that caused by DAMGO-treatment. Mu receptor phosphorylation in the thalamus was much greater than the striatum, while no phosphorylation of the mu receptor in the cerebellum was detected, even with DAMGO treatment. The extent of mu receptor phosphorylation identified in the thalamus, striatum and cerebellum is consistent with the previous studies of mu receptor distribution. The time course and dose-response studies demonstrated that mu receptor phosphorylation was a rapid event, exhibited a positive dose-dependent response, and was similar to that observed in the cloned mu receptor in CHO cells. Furthermore, we correlated the change of mu receptor phosphorylation with the desensitization of the mu receptor function, specifically, inhibition of adenylyl cyclase activity in the thalamus of morphine-tolerant rats. We found that in the thalamus of rats chronically treated with morphine, the enhancement of mu receptor phosphorylation in basal and DAMGO-treated samples paralleled the desensitization of DAMGO-mediated inhibition of adenylyl cyclase. Our results suggest that mu receptor phosphorylation in vivo may play an important role in the modulation of mu receptor function following both acute exposure to morphine and during the development of morphine tolerance. |
| Databáze: | OpenAIRE |
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