The involvement of Cry1 and Cry2 genes in the regulation of the circadian body temperature rhythm in mice.
The criptochrome genes (Cry1 and Cry2) are involved in the molecular mechanism that controls the circadian clock, and mice lacking these genes (Cry1(-/-)/Cry2(-/-)) are behaviorally arrhythmic. It has been speculated that the circadian clock modulates the characteristics of thermoregulation, resulting in body temperature (T(b)) rhythm. However, there is no direct evidence proving this speculation. We show here that T(b) and heat production in Cry1(-/-)/Cry2(-/-) mice are arrhythmic under constant darkness. In contrast, both rhythms occur under a light-dark cycle and/or periodical food restriction linked with spontaneous activity and/or eating, although they are not robust as those in wild-type mice. The relationship between heat production and T(b) in Cry1(-/-)/Cry2(-/-) mice is linear and identical under any conditions, indicating that their T(b) rhythm is determined by heat production rhythm associated with activity and eating. However, T(b) in wild-type mice is maintained at a relatively higher level in the active phase than the inactive phase regardless of the heat production level. These results indicate that the thermoregulatory responses are modulated according to the circadian phase, and the Cry genes are involved in this mechanism.
Department of Integrative Physiology, School of Human Sciences, Waseda University, Mikajima 2-579-15, Tokorozawa, Saitama 359-1192, Japan. k-nagashima@waseda.jp
Kei
K
Nagashima
Kenta
K
Matsue
Masahiro
M
Konishi
Chisato
C
Iidaka
Koyomi
K
Miyazaki
Norio
N
Ishida
Kazuyuki
K
Kanosue
D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology*; D056931:Cryptochromes; D005420:Flavoproteins / Q000502:physiology*; D015870:Gene Expression; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D017440:Photoperiod; D022722:Thermogenesis / Q000502:physiology
C538963:CRY1 protein, human; C538966:CRY2 protein, human; C538964:Cry1 protein, mouse; C538967:Cry2 protein, mouse; D056931:Cryptochromes; D005420:Flavoproteins