| Autor: |
Dang, Vu C., Williams, John T. |
| Zdroj: |
Molecular Pharmacology; October 2005, Vol. 68 Issue: 4 p1127-1132, 6p |
| Abstrakt: |
Morphine has been widely accepted as the opioid agonist that sustains signaling because it does not cause receptor desensitization or internalization. This notion has led to the hypothesis that long-term morphine treatment initiates downstream adaptations that underlie tolerance and dependence. This study uses whole-cell recordings from neurons in the locus ceruleus to measure the potassium current induced by morphine. The results show that morphine does cause short-term desensitization. The desensitization induced by morphine was slower and smaller then that induced by [MET]5-enkephalin (ME). After a brief application of a saturating concentration of ME, the current induced by morphine was smaller, and desensitization was not observed. In tissue taken from morphine-treated animals, the peak current induced by morphine was the same as in untreated animals, but morphine-induced desensitization was facilitated. The results suggest that morphine, like other agonists, can initiate receptor desensitization to decrease signaling. |
| Databáze: |
Supplemental Index |
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