Chronic haloperidol inactivates brain noradrenergic neurons

Rats were administered haloperidol (0.5 mg/kg/day) for 21 days. Twenty percent of locus coeruleus (LC) neurons recorded were not spontaneously active, while no such neuron was observed in control animals. A further 22% of neurons (spontaneously active) had rates greater than 2 standard deviations from the mean of LC control cells. These results reveal that haloperidol has profound effects on LC neurons that develop with prolonged administration, indicating a possible role of brain noradrenergic systems in clinical effects (and possible side-effects) of this neuroleptic.