In vitro extracellular recording from nigral dopamine neurons following continuous d-amphetamine infusion

Single nigral dopamine neurons were extracellularly recorded in vitro after withdrawal from continuous d-amphetamine sulfate infusion (5.0 mg/kg per day for 7 days via subcutaneous osmotic minipumps). Seven days after withdrawal, the dopamine neurons were supersensitive to impulse-inhibition by dopamine. This increased sensitivity suggests a supersensitivity of soma/dendritic autoreceptors on these neurons, as we previously hypothesized based on a supersensitivity to intravenous apomorphine. In contrast to the day 7, the withdrawal day 1 was associated with a normosensitivity to dopamine, suggesting that the apomorphine subsensitivity observed in vivo on this day may be secondary to non-autoreceptor changes.