Abstract
The effects of κ-opioid agonist treatment on κ-opioid receptor density and on dynorphin A levels in the rat brain were studied. Rats were treated with the selective κ-opioid agonist U-69593 or vehicle for 5 d. Dynorphin A levels and κ-opioid receptor binding were measured on day 8 (3 d after the last injection) or 22 (17 d after the last injection). On day 8, κ-opioid receptor density was increased in the hypothalamus of rats treated with U-69593; there were no changes in the frontal cortex or caudate putamen. In contrast, there was an increase in dynorphin A levels in the frontal cortex and no changes in hypothalamus and caudate putamen in response to U-69593. On day 22, Bmax was decreased in frontal cortex and caudate putamen of U-69593-treated rats, whereas dynorphin A levels were increased in the caudate putamen and in the frontal cortex. These findings suggest that κ-opioid receptor agonist treatment has long-term, continually changing effects on the κ-opioid system.
Original language | English (US) |
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Pages (from-to) | 307-314 |
Number of pages | 8 |
Journal | Journal of Molecular Neuroscience |
Volume | 24 |
Issue number | 2 |
DOIs | |
State | Published - Sep 2004 |
Keywords
- κ-receptor
- Dynorphin A
- Opioids
- Rat
- U-69593
ASJC Scopus subject areas
- Neuroscience(all)
- Biochemistry
- Genetics