title: Circadian variation of mouse aqueous humor protein.
abstract: OBJECTIVE
  The first aim was to document the 24 h pattern of total protein concentration in aqueous humor of the C57BL/6J mouse strain under various environmental light-dark conditions. The second aim was to determine the diurnal/nocturnal change of aqueous humor protein concentration in the CBA/CaJ mouse strain reported to show a unique absence of diurnal/nocturnal elevation of intraocular pressure (IOP).
  
  
  METHODS
  Mice of both strains were entrained to a daily 12 h diurnal/light (6 AM to 6 PM) and 12 h nocturnal/dark cycle. Total protein concentrations of aqueous humor were determined using specimens collected from C57BL/6J mice every 4 h under standard light-dark, acute constant dark, and acute constant light conditions. Aqueous humor protein concentrations in CBA/CaJ mice were determined at three diurnal times and three nocturnal times.
  
  
  RESULTS
  The C57BL/6J mouse strain showed a higher aqueous humor protein concentration during the diurnal period than during the nocturnal period under standard light-dark conditions. This pattern persisted under acute constant dark and was modulated under acute constant light. The CBA/CaJ mouse strain showed a similar diurnal/nocturnal decrease of total aqueous humor protein concentration.
  
  
  CONCLUSIONS
  Endogenous circadian variation of aqueous humor protein concentration occurs in the C57BL/6J mouse strain. The nocturnal concentration is significantly lower than the diurnal concentration. A similar diurnal/nocturnal decrease of aqueous humor protein concentration occurs in the CBA/CaJ mouse strain, indicating that this change of aqueous humor protein is unrelated to the diurnal/nocturnal pattern of IOP.
authors.affiliation: Department of Ophthalmology, University of California, San Diego, La Jolla, CA 92093-0946, USA.
authors.forename: Linda X
authors.initials: LX
authors.lastname: Zhou
authors.forename: John H K
authors.initials: JH
authors.lastname: Liu
mesh_terms: D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism*; D002940:Circadian Rhythm; D003624:Darkness; D005136:Eye Proteins / Q000378:metabolism*; D007429:Intraocular Pressure; D008027:Light; D051379:Mice; D008810:Mice, Inbred C57BL / Q000378:metabolism* / Q000502:physiology; D008808:Mice, Inbred CBA / Q000378:metabolism* / Q000502:physiology; D009994:Osmolar Concentration
chemical_list: D005136:Eye Proteins