Related Experiment Video
Updated: Jul 4, 2026

Operant Protocols for Assessing the Cost-benefit Analysis During Reinforced Decision Making by Rodents
Published on: September 10, 2018
Trial-selective effects of U50,488H, a kappa-opioid receptor agonist, on consummatory successive negative contrast
Michael D Wood1, Jacob N Norris, Alan M Daniel
1Department of Psychology, Texas Christian University, Box 298920, Fort Worth, TX 76133, USA.
Abstract:
A series of experiments studied the effects of the kappa-opioid receptor agonist U50,488H on consummatory successive negative contrast (cSNC) in rats. In cSNC, previous experience with a 32% sucrose solution leads to greater rejection of 4% sucrose than exclusive experience with 4% sucrose. Experiments 1 and 2 revealed that U50,488H failed to influence cSNC when administered before the first downshifted trial, but either attenuated (1mg/kg) or enhanced (3 and 10mg/kg) cSNC when administered before the second downshift trial. Experiment 3 showed that U50,488H administered immediately after the first downshift trial had no effect on cSNC at the 1mg/kg dose, but tended to increase cSNC at the 3mg/kg dose. However, Experiment 4 suggested that the apparent enhancement of cSNC after 3mg/kg U50 administered posttrial 11 may have reflected the development of a conditioned taste aversion. The trial-selective attenuating effect of the low dose may reflect an anxiolytic-like property of U50,488H.
Related Concept Videos
Opioid Receptors: Overview
Analgesia and Pain Management
Opioid Analgesics: Synthetic and Semisynthetic Opioids
Desensitization and Tachyphylaxis
Several...
Drug-Receptor Interaction: Agonist
Agonists can bind to receptors in different ways. Some agonists bind directly to the receptor's active site, mimicking the endogenous ligand's action.

