title: Differential susceptibility of BALB/c, C57BL/6N, and CF1 mice to photoperiod changes.
abstract: OBJECTIVE
  Circadian disturbances common to modern lifestyles have been associated with mood disorders. Animal models that mimic such rhythm disturbances are useful in translational research to explore factors contributing to depressive disorders. This study aimed to verify the susceptibility of BALB/c, C57BL/6N, and CF1 mice to photoperiod changes.
  
  
  METHODS
  Thermochron iButtons implanted in the mouse abdomen were used to characterize temperature rhythms. Mice were maintained under a 12:12 h light-dark (LD) cycle for 15 days, followed by a 10:10 h LD cycle for 10 days. Cosinor analysis, Rayleigh z test, periodograms, and Fourier analysis were used to analyze rhythm parameters. Paired Student's t test was used to compare temperature amplitude, period, and power of the first harmonic between normal and shortened cycles.
  
  
  RESULTS
  The shortened LD cycle significantly changed temperature acrophases and rhythm amplitude in all mouse strains, but only BALB/c showed altered period.
  
  
  CONCLUSIONS
  These findings suggest that BALB/c, the preferred strain for stress-induced models of depression, should also be favored for exploring the relationship between circadian rhythms and mood. Temperature rhythm proved to be a useful parameter for characterizing rhythm disruption in mice. Although disruption of temperature rhythm has been successfully documented in untethered mice, an evaluation of desynchronization of other rhythms is warranted.
authors: Ethnopharmacology Laboratory, Department of Pharmacology, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors: Luísa K
authors: LK
authors: Pilz
authors: Chronobiology Laboratory, Department of Psychiatry and Legal Medicine, UFRGS, Porto Alegre, RS, Brazil.
authors: Caroline L
authors: CL
authors: Quiles
authors: Department of Basic Health Sciences, Universidade Federal de Ciências da Saúde de Porto Alegre, Porto Alegre, RS, Brazil.
authors: Eliane
authors: E
authors: Dallegrave
authors: Chronobiology Laboratory, Department of Psychiatry and Legal Medicine, UFRGS, Porto Alegre, RS, Brazil.
authors: Rosa
authors: R
authors: Levandovski
authors: Chronobiology Laboratory, Department of Psychiatry and Legal Medicine, UFRGS, Porto Alegre, RS, Brazil.
authors: Maria Paz L
authors: MP
authors: Hidalgo
authors: Ethnopharmacology Laboratory, Department of Pharmacology, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors: Elaine
authors: E
authors: Elisabetsky
mesh_terms: D000818:Animals; D001831:Body Temperature / Q000502:physiology*; D021081:Chronobiology Disorders / Q000503:physiopathology; D002940:Circadian Rhythm / Q000502:physiology*; D004195:Disease Models, Animal; D008297:Male; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D019964:Mood Disorders / Q000503:physiopathology; D009043:Motor Activity / Q000502:physiology; D017440:Photoperiod; D012016:Reference Values; D013045:Species Specificity; D013315:Stress, Psychological / Q000503:physiopathology; D013997:Time Factors