The effects of antipsychotic drugs on the mRNA levels of serotonin 5HT(2A) and 5HT(2C) receptors

We have looked for both global and regional changes in rat brain mRNA levels encoding serotonin 5HT(2A) and 5HT(2C) receptors following acute and chronic administration of antipsychotic drugs. In whole brain clozapine (30 mg/kg/day) elicited a transient rise in 5HT(2C) mRNA levels after 4 days and chlorpromazine (15 mg/kg/day) elicited a decrease of 20% in 5HT(2A) mRNA levels after 32 days. Regionally, 32 days treatment with haloperidol (3 mg/kg/day), sulpiride (100 mg/kg/day) or clozapine (10 mg/kg/day) resulted in a drop of approximate to 30-40% in 5HT(2C) mRNA levels in both cortex and cerebellum, and decreases (or non-significant trends) of 15-40% in 5HT(2A) mRNA levels in hippocampus, brainstem and mid brain. 4 days treatment with clozapine resulted in a 40% rise of 5HT(2C) mRNA in the mid brain and a 24% rise of 5HT(2A) mRNA in the nucleus accumbens which were not found after 32 days of treatment. These results demonstrate common chronic effects of typical and atypical drugs but unique short term effects of clozapine. (C) 1997 Elsevier Science B.V.