A physiological model of a circannual oscillator

J Biol Rhythms. 2008 Jun;23(3):252-64. doi: 10.1177/0748730408316796.

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.

MeSH terms

  • Animals
  • Circadian Rhythm*
  • Models, Biological*
  • Pituitary Gland, Anterior / metabolism
  • Pituitary Gland, Anterior / physiology
  • Prolactin / metabolism

Substances

  • Prolactin