Clin Psychopharmacol Neurosci.  2023 Nov;21(4):686-692. 10.9758/cpn.22.1016.

Changes of Locomotor Activity by Dopamine D2, D3 Agonist Quinpirole in Mice Using Home-cage Monitoring System

• Park J
• Moon E
• Lim HJ
• Kim K
• Hong YR
• Lee JH

• KMID: 2548814
• DOI: http://doi.org/10.9758/cpn.22.1016

Abstract

Objective
As dopamine is closely linked to locomotor activities, animal studies on locomotor activities using dopaminergic agents were widely done. However, most of animal studies were performed for a short period that there is a lack of longitudinal study on the effects of dopaminergic agents on locomotor activities. This study aimed to examine the longterm effect of a dopamine D2, D3 agonist quinpirole on locomotor activities in mice using a home-cage monitoring system.
Methods
The locomotor activities of Institute Cancer Research mice were measured by infrared motion detectors in home-cages under the 12-hour dark and 12-hour light condition for three days after the quinpirole injection. Quinpirole was injected at a concentration of 0.5 mg/kg intraperitoneally in the beginning of the dark phase. The locomotor activities before and after the quinpirole administration were compared by the Wilcoxon signed-rank test and one-way repeated measures ANOVA.
Results
After the quinpirole administration, the 24-hour total locomotor activity did not change (p = 0.169), but activities were significantly increased in the 12-hour dark phase sum (p = 0.013) and decreased in the 12-hour light phase sum (p = 0.009). Significant increases in the activities were observed in the dark-light difference (p = 0.005) and dark-light ratio (p = 0.005) as well.
Conclusion
This study suggests that quinpirole injection entrains the circadian rest-activity rhythm of locomotor activities. Therefore, quinpirole can be a drug that mediates locomotor activity as a dopamine agonist as well as a modulator of the circadian rhythms.

Keyword

Quinpirole; Dopamine; Infrared detector; Locomotion; Circadian rhythms