Long-term depression of a dopamine IPSC

Area of Science:

• Neuroscience
• Neuropharmacology

Background:

• Dopamine release in striatal and limbic areas is governed by ventral midbrain dopamine neuron firing patterns.
• Feedback inhibition via D2 receptor activation regulates dopamine neuron activity.

Purpose of the Study:

• To investigate stimulus-dependent long-term depression (LTD) of inhibitory postsynaptic currents (IPSCs) mediated by dopamine.
• To elucidate the role of D2 receptors and intracellular calcium in this LTD phenomenon.

Main Methods:

• Electrophysiological recordings of IPSCs.
• Extracellular recordings of neuron firing.
• Application of dopamine and receptor antagonists.
• Intracellular calcium chelation.

Main Results:

• A novel stimulus-dependent LTD of IPSCs mediated by dopamine was identified.
• This LTD required D2 receptor activation and postsynaptic intracellular calcium.
• Dopamine application mimicked LTD and prevented its induction, indicating agonist-dependent receptor activation.
• LTD induction reduced the duration of firing inhibition in dopamine neurons.

Conclusions:

• Dopamine-mediated LTD of IPSCs represents a novel form of synaptic plasticity.
• This plasticity mechanism, involving D2 receptors and calcium, can modulate dopamine neuron firing.
• Reduced inhibition may lead to increased burst firing and dopamine release in terminal regions.