Related Experiment Video
Updated: Aug 11, 2026

A Conditioned Place Preference Protocol for Measuring Incubation of Craving in Rats
Published on: November 6, 2018
Nalbuphine is effective in decreasing the rewarding effect induced by morphine in rats
Pao-Luh Tao1, Kai-Wen Liang, Wen-Yi Sung
1Department of Pharmacology, National Defense Medical Center, 161, Min-Chuan East Road, Sec. 6, Taipei 114, Taiwan, ROC.
Abstract:
Nalbuphine, a kappa-opioid agonist and mu-opioid partial agonist, has been widely used as an analgesic or an adjuvant with morphine in clinics. In rats, it attenuates tolerance and physical dependence caused by morphine, when co-administered. In this study, we investigated the effect of nalbuphine on morphine reward. Using the conditioned place preference (CPP) paradigm in rats, we demonstrated that co-administration of nalbuphine (1mg/kg, i.p.) with morphine (5mg/kg, i.p.) during conditioning could completely block the CPP induced by morphine. However, in experiments examining locomotor activity in rats, nalbuphine showed no effect on the development of behavioral sensitization induced by reported morphine administration. In microdialysis experiments, morphine induced a significant increase in the dopamine metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid in the shell region of the nucleus accumbens. Co-administration of nalbuphine blocked the increase in dopamine metabolites induced by morphine. These results may be due to the attenuating effect of nalbuphine on the dopaminergic activity of mesolimbic pathways. All of these results suggest nalbuphine could have a great potential as a pharmacotherapy for opiate abuse.
Related Concept Videos
Opioid Analgesics: Synthetic and Semisynthetic Opioids
Opioid Analgesics: Morphine and Other Natural Cogeners
Analgesia and Pain Management
Opioid Receptors: Overview
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.
Drugs Affecting Neurotransmitter Release or Uptake

