Expression of neuropeptide- and hormone-encoding genes in the Ciona intestinalis larval brain

► We identified candidates of brain genes in the Ciona larva by microarray analysis. ► Eleven peptide genes including hypothalamic peptides such as GnRH and VP were found. ► Most of the peptide genes were expressed in the ventral region of the brain. ► As to several peptide genes, their corresponding receptors were also expressed in the brain. ► These results indicate that the ventral brain region is homologous to hypothalamus.