Effects of the altered serotonergic signalling by neonatal treatment with 5,7-dihydroxytryptamine, ritanserin or clomipramine on the adrenocortical stress response and the glucocorticoid receptor binding in the hippocampus in adult rats.

The aim of the present study is to investigate the effect of neonatal alterations in 5-HT signalling on the regulation of endocrine stress response in adult rats. The neonatal blockade of 5-HT transmission by 5,7-DHT or ritanserin treatment did not alter the density of glucocorticoid receptor (GR) binding sites in the hippocampus, although a 5,7-DHT-induced lesion was clearly shown to decrease in 5-HT content by greater than 80% in the hippocampus. In addition, the animals pretreated with the blockade of 5-HT transmission during early life did not exhibit a hyperresponsiveness of the adrenocortical response to stress. On the other hand, the neonatal administration of the 5-HT uptake inhibitor, clomipramine, was shown to lower the stress responsiveness of the adrenocortical axis in adulthood.