Suprachiasmatic Nucleus - Circadian Rhythms of Endothermic and Ectothermic Vertebrates

Circadian Rhythms of Endothermic and Ectothermic Vertebrates

Information about the direct neuronal regulation of metabolic processes and circadian rhythm-controlled behaviors is not well known among either endothermic or ectothermic vertebrates, although extensive research has been done on the SCN in model animals such as the mammalian mouse and ectothermic reptiles, particularly lizards. The SCN is known to be involved not only in photoreception through innervation from the retinohypothalamic tract, but also in thermoregulation of vertebrates capable of homeostasis, as well as regulating locomotion and other behavioral outputs of the circadian clock within ectothermic vertebrates. The behavioral differences between both classes of vertebrates, when compared to the respective structures and properties of the SCN and various other nuclei proximate to the hypothalamus, provide insight into how these behaviors are the consequence of differing circadian regulation. Ultimately, many neuroethological studies must be done to completely ascertain the direct and indirect roles of the SCN on circadian-regulated behaviors of vertebrates.