Related Experiment Video
Updated: Oct 23, 2026
Operant Protocols for Assessing the Cost-benefit Analysis During Reinforced Decision Making by Rodents
Published on: September 10, 2018
The effects of dopamine D2 and D3 antagonists on spontaneous motor activity and morphine-induced hyperactivity in
C Manzanedo1, M A Aguilar, J Miñarro
1Area de Psicobiología, Facultad de Psicología, Universitat de Valencia, Spain.
Rationale:
Dopaminergic neurotransmission, in particular the mesolimbic pathway, is involved in spontaneous locomotor activity and in morphine-induced hyperactivity, since the drugs acting on DA receptors can modify the action of morphine and this effect could be dependent on the type of DA receptor affected.
Objective:
In this study, the action of U-99194A maleate, haloperidol, sulpiride and morphine (5, 10, 20, 40 mg/kg) on locomotor activity in male mice was evaluated. Likewise, the effects of these dopaminergic antagonists on morphine-induced hyperactivity were studied.
Methods:
Animals treated with U-99194A maleate (2.5, 5, 10, 20 mg/kg), haloperidol (0.075, 0.1 mg/kg), sulpiride (20, 40 mg/kg), or morphine (5, 10, 20, 40 mg/kg), and animals treated with these neuroleptics plus morphine were tested in an actimetre at different time points.
Results:
It was found that an increase in locomotor activity was produced between 0 and 30 min after the administration of 20 mg/kg U-99194A maleate and between 30 and 60 min after the administration of 20 and 40 mg/kg morphine. This dose of U-99194A maleate and the high dose of sulpiride reverts the hyperactivity induced by 20 mg/kg morphine. Haloperidol reversed the hyperactivity induced by all doses of morphine.
Conclusions:
Our results confirm that the action of DA D2 and D3 receptors could be dependent on the dopaminergic state, in this case modified by the action of morphine.
More Related Videos
Related Concept Videos
01:28Drugs Affecting GI Tract Motility: Dopamine Receptor Antagonists
01:29Drugs Affecting Neurotransmitter Synthesis
01:25Adrenergic Agonists: Indirect-Acting Agents
One mechanism involves depleting stored catecholamines by displacing them from synaptic vesicles. These agents, known as "displacers," are transported into vesicles at the expense of noradrenaline. Examples include amphetamine and tyramine, which lack a catechol moiety, resulting in prolonged action, improved oral bioavailability, and...
01:22Opioid Receptors: Overview
00:59Direct-Acting Cholinergic Agonists: Pharmacological Actions
01:23Drugs Acting on Autonomic Ganglia: Stimulants
Ganglionic stimulants activate NM nicotinic receptors in autonomic ganglia, falling into two categories: nicotine mimetics [e.g., lobeline, dimethylpiperazine, tetramethylammonium] and muscarinic receptor agonists [e.g., muscarine, methacholine]. The first category's action is rapid and blocked by nicotinic receptor antagonists, while the second category's action is delayed and blocked by atropine-like agents. Nicotine, an alkaloid, affects the heart rate by stimulating sympathetic or...