Synaptic and non-synaptic striatal dopamine D2 receptors: possible implications in normal and pathological behaviour

Area of Science:

• Neuroscience
• Receptor Pharmacology
• Behavioral Science

Background:

• The central nervous system exhibits multi-level organization, from molecular to neuronal systems.
• Dopamine D2 receptors in the striatal complex are crucial for understanding the link between receptor function and behavior, particularly in extrapyramidal and limbic systems.

Purpose of the Study:

• To investigate the role of dopamine D2 receptor organization and function within the striatal complex.
• To examine how alterations in dopamine signaling affect receptor activation and subsequent behavior, focusing on conditions like amphetamine exposure and Parkinson's disease.

Main Methods:

• Distinguishing between striosomal and matrix compartments within the striatal complex.
• Analyzing dopamine D2 receptor density in different striatal compartments.
• Examining the impact of dopamine overflow and degeneration on receptor localization and function.

Main Results:

• The matrix compartment of the striatum has a higher density of dopamine D2 receptors compared to the striosomes.
• Under normal conditions, dopamine occupies most D2 receptors, making postsynaptic function sensitive to antagonists.
• Drug-induced dopamine overflow and L-DOPA therapy in Parkinson's disease can lead to non-synaptic receptor activation and loss of normal spatial-temporal organization.

Conclusions:

• Dopamine D2 receptor distribution and occupancy are critical for normal brain function.
• Disruptions in dopamine signaling and receptor localization, as seen in Parkinson's disease and with certain drugs, can lead to aberrant receptor activation and behavioral deficits.