The influence of chronic treatment with antidepressant neuroleptics on the central serotonin system.

Chronic administration of antidepressant neuroleptics chlorprothixene (CPX) and levomepromazine (LMZ) increases the sensitivity of one kind of serotonergic receptors in CNS-5-HT2 receptors (which are involved in such behavioral responses as head-twitches and hyperthermia in heat adapted rats), but do not change 5-HT1 receptor population (responsible for the rate of serotonin synthesis). These results confirm once more the hypothesis about the existence of at least two types of serotonin receptors in the CNS. They also indicate that antidepressant neuroleptics, which are potent serotonin 5-HT2 and alpha 1-adrenergic blocking agents, after chronic administration affect the serotonin system in a manner similar to that produced by chronic treatment with classical antidepressant drugs.