Benoit-Marand Marianne, O'Donnell Patricio
Center for Neuropharmacology & Neuroscience, Albany Medical College, 47 New Scotland Ave., Albany, NY 12208, USA.
Eur J Neurosci. 2008 Mar;27(6):1364-72. doi: 10.1111/j.1460-9568.2008.06107.x. Epub 2008 Mar 7.
Dopaminergic afferents from the ventral tegmental area (VTA) modulate information processing in the nucleus accumbens (NA), a brain region critical for motivation and reward mechanisms. In NA medium spiny neurons (MSNs) from young rats, D(2) agonists have been shown to decrease the amplitude of corticoaccumbens synaptic responses. As several dopamine-related functions change during adolescence, we assessed the D(2) modulation of cortical inputs with whole-cell recordings in slices obtained from adult and preadolescent rats. The D(2) agonist quinpirole (5 microM) decreased synaptic response of NA MSNs to electrical cortical stimulation in slices from preadolescent rats. In slices from adult rats, however, quinpirole increased both the amplitude of evoked synaptic responses and the frequency of spontaneous synaptic events. These effects were blocked by the GABA-A antagonist picrotoxin (50 microM), revealing a D(2)-mediated decrease These results suggest that D(2) receptors modulate NA neurons differently in young and adult rats, due to the emergence of a D(2)-facilitated GABA component in corticoaccumbens responses during adolescence.
来自腹侧被盖区（VTA）的多巴胺能传入纤维调节伏隔核（NA）中的信息处理，伏隔核是对动机和奖励机制至关重要的脑区。在幼鼠的NA中型多棘神经元（MSN）中，D（2）激动剂已被证明可降低皮质-伏隔核突触反应的幅度。由于几种与多巴胺相关的功能在青春期会发生变化，我们用全细胞膜片钳记录技术评估了从成年大鼠和青春期前大鼠获取的脑片中皮质输入的D（2）调节情况。D（2）激动剂喹吡罗（5微摩尔）降低了青春期前大鼠脑片中NA MSN对皮质电刺激的突触反应。然而，在成年大鼠脑片中，喹吡罗增加了诱发突触反应的幅度和自发突触事件的频率。这些效应被GABA-A拮抗剂印防己毒素（50微摩尔）阻断，揭示了一种D（2）介导的降低。这些结果表明，由于青春期皮质-伏隔核反应中出现了D（2）促进的GABA成分，D（2）受体对幼鼠和成年大鼠的NA神经元的调节方式不同。
