Hormones play pivotal roles in our well-being, and even more so in times of stress or disease. They determine body composition and govern reproductive processes. Hormonal compounds tend to be evolutionarily very old compounds, but only coevolved receptor systems make up powerful biological signals. We will discuss what makes some metabolites good building materials for hormones and how information may be encoded, using these scaffolds. Starting with hormone biosynthesis and regulated release from secreting cells, we will look at different stages of the whole hormone signaling process: the distribution of the hormonal "message-in-a-bottle" throughout the body, the passing of some hormones through membranes, and pre-receptor metabolism. Binding to different classes of receptors is not the end of hormone signaling, but the beginning of a second phase of signaling via second messengers, before hormonal messages are switched off again. Studying hormone biochemistry will produce exciting new findings in the future.
