An-Chih Chang

κ-Opioid receptor agonist suppression of HIV-1 expression in CD4+ lymphocytes

Synthetic kappa-opioid receptor (KOR) agonists have been shown to suppress HIV-1 expression in acutely infected macrophages. In the present study, we examined the effects of the KOR ligand trans-3,4-dichloro-N-methyl-N[2-(1-pyrolidinyl)cyclohexyl]benzeneaceamide methanesulfonate (U50,488) on HIV-1 expression in CD4+ lymphocytes, the main target cell of this virus. When U50,488 was added to activated CD4+ lymphocytes, HIV-1 expression was inhibited in a concentration- and time-dependent manner with maximal suppression (approximately 60%) at 10(-7) M U50,488. The KOR selective antagonist nor-binaltorphimine (nor-BNI) had no effect by itself on viral expression but blocked the antiviral property of U50,488, suggesting that U50,488 was acting via a KOR-related mechanism. Support for the involvement of KOR was provided by the findings that 34% of activated CD4+ lymphocytes were positive for KOR, using an immunofluorescence technique, and that seven additional synthetic KOR ligands also inhibited HIV-1 expression. The results of this study broaden understanding of the antiviral properties of KOR ligands to include cells outside of the nervous system and suggest a potential role for these agents in the treatment of HIV-1 infection.

A guinea pig ileum preparation devoid of functional κ receptors: A new in vitro pharmacologic assay for μ-opioid ligands

Abstract Guinea pig ileum longitudinal muscle/myenteric plexus preparations contain functional μ- and κ-opioid receptors. A preparation with blocked κ receptors was obtained by pretreating guinea pigs with 0.1–10.0 mg kg intraperitoneal doses of a new κ-selective affinity label, DIPPA (2-(3,4-dichlorophenyl)-N-methyl-N-[1S-1-(-3-isothiocyanatophenyl)-2-(-1-pyrrolidinyl) ethyl] acetamide). Determination of IC50 values for the μ-selective agonist DAMGO ([D-Ala2,MePhe4,Gly(ol)5]-enkephalin) and the κ-selective agonist U 69,593 ([5α,7α,8β]-(+)-N-methyl-N-[7-(1-pyrrolidinyl)-1-oxaspiro-(4,5)-dec-8-yl]) showed that 0.5 mg kg DIPPA at 48 h produced reliable, near-complete blockade of κ-opioid activity but a minimal shift for μ-opioid agonism. This new assay should be useful for studying mixed agonists/antagonists that produce strong κ-opioid receptor agonism, which prevents determination of μ-opioid receptor antagonism.