D2 dopamine modulation of corticoaccumbens synaptic responses changes during adolescence

Area of Science:

• Neuroscience
• Neuropharmacology
• Adolescent Development

Background:

• Dopaminergic pathways from the ventral tegmental area (VTA) are crucial for motivation and reward, modulating nucleus accumbens (NA) function.
• Previous studies indicated D2 receptor agonists decrease corticoaccumbens synaptic responses in young rats' NA medium spiny neurons (MSNs).
• Dopamine system functions undergo significant changes during adolescence.

Purpose of the Study:

• To investigate the age-dependent effects of D2 receptor modulation on cortical inputs to NA MSNs.
• To compare D2 receptor-mediated synaptic plasticity in preadolescent versus adult rats.

Main Methods:

• Whole-cell recordings were performed on NA MSNs in brain slices from preadolescent and adult rats.
• The D2 receptor agonist quinpirole was used to assess synaptic responses to electrical cortical stimulation.
• The role of GABAergic neurotransmission was examined using the GABA-A antagonist picrotoxin.

Main Results:

• In preadolescent rats, quinpirole decreased the amplitude of corticoaccumbens synaptic responses.
• In adult rats, quinpirole increased both the amplitude of evoked synaptic responses and spontaneous synaptic event frequency.
• These D2-mediated effects in adults were significantly reduced by picrotoxin, indicating a D2-facilitated GABA component.

Conclusions:

• D2 receptor modulation of NA MSNs exhibits distinct patterns in preadolescent and adult rats.
• Adolescence is characterized by the emergence of a D2-facilitated GABAergic influence on corticoaccumbens pathways.
• These findings highlight critical developmental changes in dopamine signaling within the brain's reward circuitry.