Selective sigma receptor agonist and antagonist affect dopamine neuronal activity

Area of Science:

• Neuroscience
• Pharmacology

Background:

• Dopamine (DA) neurons in the substantia nigra are crucial for motor control.
• Sigma receptors are implicated in various neurological functions, but their interaction with dopamine systems requires further elucidation.

Purpose of the Study:

• To investigate the effects of a selective sigma receptor agonist and antagonist on dopamine neuron activity.
• To explore the relationship between sigma receptors and the dopamine system in the substantia nigra.

Main Methods:

• Extracellular recordings were employed to monitor the firing rate of dopamine neurons.
• Administration of the sigma receptor agonist (+)-[3H]3-(3-hydroxyphenyl)-N-(1-propyl)piperidine ((+)-3-PPP) and antagonist BMY 14802.
• Dose-response analysis was conducted for (+)-3-PPP, with and without BMY 14802 pretreatment.

Main Results:

• Intravenous administration of (+)-3-PPP caused a dose-dependent decrease in DA neuron firing rate.
• The inhibitory effects of (+)-3-PPP on DA neurons were fully reversible upon administration of BMY 14802.
• Pretreatment with BMY 14802 shifted the dose-response curve of (+)-3-PPP to the right, indicating competitive antagonism.

Conclusions:

• These findings demonstrate a significant interaction between sigma receptors and the dopamine system.
• The results support a model for studying agonist/antagonist interactions at sigma receptors within the context of dopaminergic neurotransmission.