New Effects of Haloperidol

The dopaminergic system regulates essential physiological functions, including the reward system, motivation, learning, and motor control. Disruptions in its function can, therefore, have profound and multifaceted effects on human health. While the mechanisms of action for many drugs aimed at stabilizing dopaminergic activity are wellunderstood, the effects of these drugs on the free dopamine available for receptor binding remain largely unexplored. This study examined the impact of a single injection of haloperidol (1 mg/kg), a D2 receptor antagonist and antipsychotic medication used in the treatment of schizophrenia, on extracellular dopamine concentrations in the nucleus accumbens, utilizing fast-scan cyclic voltammetry. Our results demonstrate that haloperidol administration increased extracellular dopamine levels threefold (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$p=0.012$</tex>) for at least one-hour post-injection. Furthermore, we observed that haloperidol affected the timing of peak dopamine levels, which increased by 1.3 times (<tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$p=0.023$</tex>), indicating potential secondary inhibitory processes within the ventral tegmental area - nucleus accumbens pathway. To provide context for these findings, fast-scan cyclic voltammetry data from dopamine transporter knock-out rats, which exhibit impaired dopamine reuptake and chronically elevated dopamine levels, are also presented.