REPEATED TREATMENT WITH ELECTROCONVULSIVE SHOCK INCREASES NUMBERS OF SEROTONIN-1A RECEPTORS IN THE RAT HIPPOCAMPUS

The effect of repeated treatment with electroconvulsive shock (ECS) on central serotonin1A (5-HT1A) receptor function was studied in the rat frontal cortex, hippocampus and midbrain plus pons. After repeated tr eatment with ECS the density of [H-3]8-hydroxy-2-(di-n-propylamino)tet ralin ([H-3]8-OH-DPAT) binding sites (5-HT1A receptor) was increased i n the hippocampus but not in the frontal cortex and the midbrain plus pons, while 5-HT metabolism was not changed in the hippocampus but was enhanced in the frontal cortex and the midbrain plus pons. In additio n, lesioning of 5-HT terminals with p-chloroamphetamine (PCA) did not change the up-regulation of [H-3]8-OH-DPAT binding sites by ECS. 5-HT1 A receptor-mediated behavior (forepaw treading) was enhanced by repeat ed treatment with ECS. These results suggested that repeated treatment with ECS caused the up-regulation of post-synaptic 5-HT1A receptors i n the hippocampus and this effect occurred at the post-synaptic level rather than being triggered by a change in the pre-synaptic 5-HT activ ity.