The invention provides a novel family of biologically active neuropeptides and the nucleic aid molecules coding for same. The peptides are derived for the C-terminus of the teneurin family peptides (Ten M1-4). These novel peptides, referred to as teneurin C-terminal associated peptides (TCAPs) are active in neuronal communication and are implicated in a number of neuropathologies. They are particularly useful in modulating stress responses and anxiety and in the treatment of cancer.