Abstract
Nonpeptidic δ-opioid agonists produce a number of behaviors, such as antidepressant-like effects, locomotor stimulation, antinociception, and convulsions. To consider this class of compounds as potential therapeutics for humans, the effects of δ-opioid agonists after repeated administration must be evaluated. Therefore, the present study investigated the effects of repeated δ-opioid agonist, SNC80 ([(+)-4-[(αR)-α-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-methoxyphenyl)-methyl]-N,N-diethylbenzamide), administration on its antidepressant-like effects in the forced swim test, locomotor activity, and convulsions in male Sprague-Dawley rats. Tolerance developed rapidly to the convulsive and locomotor-stimulating effects of SNC80 but not to the antidepressant-like effects. In addition, tolerance was evaluated at the level of the receptor-G protein interaction by measuring 5′-O-(3-[35S]thio)triphosphate binding in brains from rats that were pretreated with SNC80. With various exposure durations to SNC80, some brain regions demonstrated tolerance at different times, suggesting that adaptations in the δ-opioid system may occur during agonist exposure. Overall, the lack of observable tolerance to the antidepressant-like effects of SNC80 indicates that this class of compounds has potential as a novel antidepressant therapy.
Footnotes
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This work was supported by U. S. Public Health Service Grants DA00254, T32 GM07767, and T32 DA07267.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.105.088831.
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ABBREVIATIONS: (+)BW373U86, [(+)-4-[(αR)-α-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-hydroxyphenyl)methyl]-N,N-diethylbenzamide; SNC80, [(+)-4-[(αR)-α-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-methoxyphenyl)methyl]-N,N-diethylbenzamide; [35S]GTPγS, 5′-O-(3-[35S]thio)triphosphate; ANOVA, analysis of variance; NSB, nonspecific binding.
- Received April 29, 2005.
- Accepted July 12, 2005.
- The American Society for Pharmacology and Experimental Therapeutics
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