Postsynaptic localization and up-regulation of serotonin 5-HT1D receptors in rat brain

Serotonin lesioning studies were performed to determine the synaptic localization of the 5-HT1D receptor. Four days following p-chloroamphetamine (PCA; 5 mg/kg x 4) [3H]paroxetine-labeled uptake sites (a marker for 5-HT terminals) were reduced to 18% of control values in the cortex and 29% of control values in the striatum, while the number of 5-HT1D receptors remained unchanged. Fourteen days following PCA administration an up-regulation of cortical 5-HT1D receptors was observed. These findings indicate that 5-HT1D receptors are localized postsynaptically in the cortex and striatum, and that denervation of endogenous serotonergic input produces a compensatory up-regulation in the cortex.