Differential effects of chronic antidepressant treatment on 5-HT1C receptor binding sites in Wistar rat brain.

The effects of chronic clomipramine, imipramine and clorgyline on 5-HT1C receptors were studied in discrete brain regions, in male Wistar rats, using [3H]mesulergine to label the receptor binding sites. Clorgyline treatment significantly reduced [3H]mesulergine binding (Bmax values) in both the hypothalamus and striatum compared to saline-treated animals. There were no differences in the maximum number of [3H]mesulergine binding sites following clorgyline in the hippocampus, frontal cortex or brainstem. Neither clomipramine or imipramine treatment resulted in any significant changes in 5-HT1C receptor number in the brain regions examined here. Furthermore, the Kd values (receptor affinity) for [3H]mesulergine binding were not significantly different comparing treatment groups to control animals. The significant changes in discrete brain regions following chlorgyline treatment suggest that 5-HT1C receptors may be involved in the clinical efficacy for the treatment of depression and other neuropsychiatric disorders.