“Non-serotonergic” lateral superior olivary neurons of the neonatal mouse contain serotonin

In mutant mice which have high serotonin (5-HT) levels perinatally, neurons in the lateral superior olive (LSO, which are not serotonergic), contain 5-HT transiently in the neonatal period of development. We determined that the same phenomenon occurs in non-genetically altered mice: LSO neurons were 5-HT-immunoreactive at postnatal days 1 and 8. These findings suggest accumulation of 5-HT in by LSO neurons during postnatal development.