Metamorphosis is controlled by steroid hormones, which alter gene expression in target cells.
In response to hormonal cues, individual neurons may exhibit dendritic growth, dendritic regression or programmed cell death. These effects underlie the reorganization of neural circuits that produce different behaviors in the different life stages. Steroid hormones similarly influence the developing vertebrate nervous system, and steroid hormone receptors are evolutionarily conserved in insects and vertebrates. Our goal is to understand fundamental cellular and molecular mechanisms by which steroids alter neuronal phenotype. In Manduca , we address these issues at the level of individually identified neurons and at synaptic connections between identified pre- and postsynaptic neurons with known behavioral functions.