Developmental expression of 5-HT7 receptor mRNA in rat brain visual structures after neonatal enucleation.

Binocular enucleation is a useful experimental tool for studying mechanisms of neuronal plasticity. Serotonin (5-HT) is a neuromodulator that mediates a wide range of physiological functions by activating multiple receptors. We have performed an in situ hybridization study to analyse in detail the regional distribution of 5-HT7 receptor mRNA expression during postnatal development in different brain visual areas following neonatal binocular enucleation. We found that eye removal clearly induced 5-HT7 receptor mRNA expression in the stratum opticum of superior colliculus, this effect being especially evident at postnatal day 21 (P21). Similarly, there was a clear lesion-induced up-regulation of receptor mRNA expression in the primary visual cortex from P15 through P21. These results suggest a plastic role of 5-HT7 receptor during neurogenesis triggered by eye removal.