title: A physiological model of a circannual oscillator.
abstract: Recent evidence based on studies in hypothalamo-pituitary disconnected Soay sheep suggests that the generation of circannual rhythms may be local to specific tissues or physiological systems. Now, the authors present a physiological model of a circannual rhythm generator centered in the pituitary gland based on the interaction between melatonin-responsive cells in the pars tuberalis that act to decode photoperiod, and lactotroph cells of the adjacent pars distalis that secrete prolactin. The model produces a self-sustained, circannual rhythm in endocrine output that the authors explore by mathematical modeling. The circannual oscillation requires a delayed negative feedback mechanism. The authors highlight specific features of the pituitary dynamics as a guide to future research on circannual rhythms.
authors.affiliation: Centre for Integrative Physiology, University of Edinburgh, Edinburgh, UK.
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Macgregor
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Lincoln
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D008954:Models, Biological; D010903:Pituitary Gland, Anterior / Q000378:metabolism / Q000502:physiology; D011388:Prolactin / Q000378:metabolism
chemical_list: D011388:Prolactin