Genetic pathways in the developmental specification of hypothalamic neuropeptide and midbrain catecholamine systems.

The neuropeptide concept concerns the diverse and broad physiological functions of neuropeptides in behavioral adaptation. Neuropeptides like vasopressin and corticotropin-releasing hormone can coordinate multiple brain functions due to the anatomical organization of the neurons producing them. The cell bodies are focally positioned in the hypothalamus and send long-reaching efferents to limbic and brainstem areas. Likewise, midbrain dopamine systems coordinate emotional behaviors and movement control by specific connectivity of neurons in the midbrain to limbic and striatal centers, respectively. The fundament of the functions of these signalling molecules is laid out during development when transmitter identity and connectivity are specified. This is a highly controlled process involving multiple transcription factors and growth factors acting together in genetic pathways. Here, the genetic pathways enrolling in developing vasopressin, corticotropin-releasing hormone, and midbrain dopamine neurons are discussed.