Pharmacological selectivity of CTAP in a warm water tail-withdrawal antinociception assay in rats

Caren L Steinmiller, Alice Young

Research output: Contribution to journalArticle


Rationale To facilitate in vivo characterization of the mu antagonist Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH2 (CTAP), the present study characterized CTAP selectivity in vivo. Objectives CTAP, the classical antagonist naltrexone, the kappa-selective antagonist nor-binaltorphimine (BNI), and the delta-selective antagonist naltrindole were compared as antagonists of representative mu, kappa, and delta agonists in a warm water tail-withdrawal assay. Materials and methods Male Sprague–Dawley rats were pretreated with CTAP (0.01 to 10.0 μg, i.c.v.), naltrexone (0.1 to 10 mg/kg s.c.; 0.1 to 10 μg i.c.v.), nor-BNI (1 mg/kg s.c.), or naltrindole (0.01 to 1 μg, i.c.v.) and tested with cumulative doses of agonist in 50 or 55°C tail-withdrawal assays. Results At 55°C, morphine and DAMGO produced dose-dependent antinociceptive effects that were antagonized by CTAP or naltrexone (s.c. or i.c.v.) in a surmountable, dose-dependent manner. Neither kappa agonists (bremazocine, spiradoline, U69,59
Original languageEnglish
Pages (from-to)497-507
StatePublished - 2008


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