Serotonin receptor activation enhances neurite outgrowth of thalamic neurones in rodents

Serotonin (5-HT) has been shown to influence the development of the rodent barrel field by affecting the patterning of thalamic axons in the somatic s ensory cortex. To determine whether this is a direct effect on thalamocorti cal neurones, we analyzed primary thalamic cultures taken from E15 mouse em bryos. We show that 5-HT enhances neurite outgrowth of thalamic neurones. T he sodium channel blocker, TTX, blocks these effects, whereas the selective 5-HT1B agonist CGS-12066A maleate reproduced 5-HT's effect. Using PCR and immunocytochemistry, we found that 5-HT1B receptors are already expressed b y thalamic neurones at E15, and that this expression is maintained in vitro . These results suggest that 5-HT-1B receptor activation directly affects t he growth of thalamocortical axons. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.