Behavioral aspects of serotonin-dopamine interaction in the monkey

Area of Science:

• Neuroscience
• Pharmacology
• Behavioral Science

Background:

• Serotonin (5-hydroxytryptamine; 5-HT) plays a crucial role in modulating neurotransmitter systems.
• Dopamine pathways are implicated in motor control and psychiatric disorders.
• Understanding 5-HT interactions with dopamine is key to developing effective treatments.

Purpose of the Study:

• To investigate the effects of 5-HT antagonists and uptake inhibitors on behaviors induced by amphetamine and haloperidol in monkeys.
• To explore the potential of these agents in managing drug-induced movement disorders.
• To establish a primate model for tardive dyskinesia.

Main Methods:

• Administered amphetamine and haloperidol to cynomolgus monkeys (cercopithecus aethiops).
• Pretreated subjects with 5-HT antagonists (cyproheptadine, mianserin) and 5-HT uptake inhibitors (paroxetine, CGP 6085 A).
• Observed and quantified behavioral responses, including locomotor activity, reactivity, and specific movement patterns.

Main Results:

• 5-HT antagonists enhanced amphetamine effects and reduced haloperidol-induced parkinsonism and dystonia.
• 5-HT uptake inhibitors decreased amphetamine-induced repetitive movements and worsened haloperidol effects.
• 5-HT uptake inhibitors induced oral hyperkinesia, a potential model for tardive dyskinesia.

Conclusions:

• Findings suggest 5-HT inhibits dopamine functions.
• 5-HT antagonists may offer benefits against acute extrapyramidal side effects of neuroleptics.
• 5-HT uptake inhibitors in monkeys provide a relevant model for studying tardive dyskinesia.