Dopamine enhancement of dextrorphan-induced skin antinociception in response to needle pinpricks in rats

Yu Yu Li, Chong Chi Chiu, Jhi Joung Wang, Yu Wen Chen, Ching Hsia Hung

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Background: Dextrorphan with long-acting local anesthetic effects did not cause system toxicity as fast as bupivacaine, while catecholamines (i.e., epinephrine) with the vasoconstrictive characteristics enhanced the effects of local anesthetic drugs. The objective of the experiment was to examine the synergistic effect of local dopamine (a catecholamine) injection on cutaneous antinociception of dextrorphan. Methods: The panniculus reflex in response to skin stimulation with a needle was used as the primary endpoint when dextrorphan (1.50, 2.61, 5.46, 10.20 and 20.40 μmol) alone, dopamine (16.20, 32.40, 51.60, 60.00 and 81.60 μmol) alone, or dopamine + dextrorphan (a ratio of ED50 vs. ED50) was injected subcutaneously on the rat's back. We used an isobolographic modelling approach to determine whether a synergistic effect would be observed. Results: We showed that dextrorphan, dopamine, or the mixture of dopamine and dextrorphan produced dose-related skin antinociception. The potency (ED50, 50% effective dose) for cutaneous antinociception was dextrorphan [6.02 (5.93–6.14) μmol] greater than dopamine [48.91 (48.80–49.06) μmol] (p < 0.01). The duration of nociceptive inhibition induced by dopamine was longer than that induced by dextrorphan (p < 0.01) based on their equipotent doses (ED25, ED50, and ED75). Enhancement and prolongation of skin antinociception occurred after co-administration of dopamine with dextrorphan. Conclusions: When compared to dopamine, dextrorphan was more potent and had a shorter duration of skin nociceptive block. Dopamine produced a synergistic effect on dextrorphan-mediated antinociception, and prolonged dextrorphan′s antinociceptive duration.

Original languageEnglish
Pages (from-to)732-737
Number of pages6
JournalPharmacological Reports
Issue number4
Publication statusPublished - 2019 Aug

All Science Journal Classification (ASJC) codes

  • Pharmacology

Fingerprint Dive into the research topics of 'Dopamine enhancement of dextrorphan-induced skin antinociception in response to needle pinpricks in rats'. Together they form a unique fingerprint.

Cite this