Evolution and physiology of the corticotropin-releasing factor (CRF) family of neuropeptides in vertebrates

Corticotropin-releasing factor (CRF), urotensin-I, urocortin and sauvagine belong to a family of related neuropeptides found throughout chordate taxa and likely stem from an ancestral peptide precursor early in metazoan ances try In vertebrates, current evidence suggests that CRF on one hand, and uro tensin-I, urocortin and sauvagine, on the other, form paralogous lineages. Urocortin and sauvagine appear to represent tetrapod orthologues of fish ur otensin-I. Sauvagine's unique structure may reflect the distinctly derived evolutionary history of the anura and the amphibia in general. The physiolo gical actions of these peptides are mediated by at least two receptor subty pes and a soluble binding protein. Although the earliest functions of these peptides may have been associated with osmoregulation and diuresis, a cons tellation of physiological effects associated with stress and anxiety, vaso regulation, thermoregulation, growth and metabolism, metamorphosis and repr oduction have been identified in various vertebrate species. The elaboratio n of neural circuitry for each of the two paralogous neuropeptide systems a ppears to have followed distinct pathways in the actinopterygian and sarcop terygian lineages of vertebrates. A comparision of the functional differenc es between these two lineages predicts additional functions of these peptid es. (C) 1999 Academic Press.