In vivoevidence that genetic background controls impulse‐dependent dopamine release induced by amphetamine in the nucleus accumbens

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Abstract
Amphetamine is known to increase dopamine (DA) release by acting directly on dopamine transporters (DAT), primarily through a mechanism that is independent of impulse flow. We present evidence to show that impulse‐dependent increase in DA outflow in the nucleus accumbens (NAc) is produced by amphetamine depending on genetic background. Systemic amphetamine produced higher accumbal DA release in the widely exploited C57BL/6J background than in the DBA/2J. By contrast, intra‐accumbens perfusion using increasing doses of amphetamine dramatically increased DA outflow in the DBA/2J background, whereas very low DA outflow was evident in C57BL/6J mice. The fast sodium channel blocker tetrodotoxin infused through the microdialysis probe abolished accumbal DA release induced by systemic amphetamine only in the C57BL/6J background. Finally, medial prefrontal excitotoxic lesion abolished amphetamine‐induced mesoaccumbens DA release in C57BL/6J mice, without significantly affecting it in the DBA/2J background. These results represent the first functional evidence in anin vivostudy that amphetamine can increase DA release in the NAc mainly through an impulse‐dependent mechanism regulated by prefronto‐cortical glutamatergic transmission. Moreover, they point to a genetic control of impulse‐dependent DA release in the accumbens, providing an exploitable tool to investigate aetiological factors involved in psychopathology and drug addiction.

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