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We showed previously that cAMP response element-binding protein (CREB) within the nucleus accumbens (NAc) of rats regulates immobility in the forced swim test (FST), an assay used to study depression. Because CREB regulates expression of dynorphin (which acts at kappa-opioid receptors) in NAc neurons, these findings raised the possibility that(More)
The opioid antagonist activities of two bivalent ligands, BNI and nor-BNI, have been evaluated in smooth muscle preparations and in mice. Both ligands are highly potent and selective as kappa opioid receptor antagonists, with relatively feeble blocking activity at mu and delta opioid receptors. BNI and nor-BNI represent the first highly selective kappa(More)
Progress in opioid research relies heavily on ligands as probes to evaluate selectivity of action. The design of such ligands using naltrexone as a precursor has afforded a number of highly selective antagonists. These include the kappa opioid receptor antagonist, norBNI, and delta opioid receptor antagonists, NTI and NTB. The unifying concept in the(More)
The effects of opioid agonists with selectivity for kappa, mu and delta types of opioid receptors on the K+-stimulated release of [3H]dopamine (DA) from striatum and cortex of rat and guinea pig loaded previously with the monoamine have been studied. The kappa agonist U50488H did not affect base-line release of [3H]DA measured in 5 mM K+, but produced a(More)
In view of recent pharmacological studies suggesting the existence of delta-kappa opioid receptor heterodimers/oligomers in the spinal cord, we have synthesized and evaluated (intrathecally in mice) a series of bivalent ligands (KDN series) containing kappa and delta antagonist pharmacophores. Pharmacological and binding data have provided evidence for the(More)
RATIONALE Elevations in cAMP response element binding protein (CREB) function within the mesolimbic system of rats reduce cocaine reward in place conditioning studies and increase immobility in the forced swim test. Each of these behavioral adaptations can be interpreted as a depressive-like effect (i.e., anhedonia, despair) that may reflect reduced(More)
There has been much speculation regarding the functional relevance of G protein-coupled receptor heterodimers, primarily because demonstrating their existence in vivo has proven to be a considerable challenge. Here we show that the opioid agonist ligand 6'-guanidinonaltrindole (6'-GNTI) has the unique property of selectively activating only opioid receptor(More)
Antagonists selective for either kappa- [e.g. nor-binaltorphimine (nor-BNI)] and mu- (e.g. beta-funaltrexamine) opioid receptors have previously been shown to reduce both kappa- and mu-opioid-induced feeding. In the present studies, the anorectic effects of GNTI, a newly synthesized antagonist selective for kappa-opioid receptors, were studied in rats. GNTI(More)
The profile of action of beta-funaltrexamine (beta-FNA), the fumaramate methyl ester derivative of naltrexone, on antinociceptive tests in vivo was investigated. Beta-FNA demonstrated antinociceptive actions that were of short duration and that appeared to be mediated by kappa receptor interaction. In contrast, the antagonist actions of beta-FNA were of(More)