title: Circadian rhythms and the effects of exogenous melatonin in the nine-banded armadillo, Dasypus novemcinctus: a mammal lacking a distinct pineal gland.
abstract: Circadian rhythms of body temperature, activity and oxygen consumption were recorded in the nine-banded armadillo, Dasypus novemcinctus, a mammal lacking a distinct pineal gland. The rhythms were entrained by light-dark cycles and appeared to be phase-coupled. Under constant illumination, the animals displayed free-running circadian rhythms with period lengths of slightly less than 24 hr. Melatonin implants caused a lengthening of the free-running period of activity and body temperature. The occurrence of a "normal" circadian rhythmicity in the armadillo indicates that the pineal organ is not necessary for the circadian organization of this animal whereas melatonin of non-pineal origin may have a role.
mesh_terms: D000818:Animals; D001135:Armadillos / Q000502:physiology*; D001833:Body Temperature Regulation; D002940:Circadian Rhythm; D004734:Energy Metabolism; D008550:Melatonin / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology; D010870:Pineal Gland / Q000502:physiology*; D004490:Xenarthra / Q000502:physiology*
chemical_list: D008550:Melatonin