title: Aerobic exercise increases tear secretion in type 2 diabetic mice.
abstract: OBJECTIVE
  To investigate the effects of exercise on tear secretion in type 2 diabetic mice, and to investigate the effect of the adenosine monophosphate-activated protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR).
  
  
  METHODS
  Heterozygous controls (db/m; m Lepr(db)) and type 2 diabetic mice (db/db; Lepr(db)) either underwent forced treadmill exercise training 5 days a week or remained sedentary for 8 weeks. Tear secretion volume was measured by cotton threads for 30 seconds pre- and post intervention. The levels of oxidative stress markers (8-hydroxy-2'-deoxyguanosine [8-OHdG], propanoyl lysine [PRL], and hexanoyl lysine [HEL]) in tears were measured in the postintervention period. Furthermore, C57BL/6JJc1 mice, db/db mice, and db/m mice received a single intraperitoneal injection of AICAR or PBS each day for 5 days, and tear secretion volume was measured.
  
  
  RESULTS
  Exercise training for 8 weeks increased tear secretion volume in db/m and db/db mice. The levels of oxidative stress markers in tears were less in the exercise group than in the control group. In C57BL/6JJc1 mice, the tear secretion volumes in both the AICAR 125 mg/kg and AICAR 250 mg/kg groups were significantly larger than in the PBS group (P < 0.01 and P < 0.01, respectively). Additionally, in db/db mice, tear secretion volume in the AICAR 125 mg/kg group was also significantly larger than in the PBS group (P < 0.05).
  
  
  CONCLUSIONS
  Exercise training for 8 weeks and a daily injection of AICAR for 5 days increased tear secretion in mice. The results suggest that exercise may be a potential therapy to modulate tear secretion.
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Kokoro
authors.initials: K
authors.lastname: Sano
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Motoko
authors.initials: M
authors.lastname: Kawashima
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Ito
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan.
authors.forename: Takaaki
authors.initials: T
authors.lastname: Inaba
authors.affiliation: Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.
authors.forename: Kohkichi
authors.initials: K
authors.lastname: Morimoto
authors.affiliation: Health Science Laboratory, Keio Research Institute at Shonan-Fujisawa Campus, Keio University, Tokyo, Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Watanabe
authors.affiliation: Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan Health Science Laboratory, Keio Research Institute at Shonan-Fujisawa Campus, Keio University, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tsubota
mesh_terms: D000620:Aminoimidazole Carboxamide / Q000008:administration & dosage / Q000031:analogs & derivatives; D000818:Animals; D001786:Blood Glucose / Q000187:drug effects / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005260:Female; D007004:Hypoglycemic Agents / Q000008:administration & dosage; D007274:Injections, Intraperitoneal; D051379:Mice; D008810:Mice, Inbred C57BL; D018384:Oxidative Stress; D010805:Physical Conditioning, Animal / Q000502:physiology*; D012265:Ribonucleotides / Q000008:administration & dosage; D013666:Tears / Q000187:drug effects / Q000378:metabolism*
chemical_list: D001786:Blood Glucose; D007004:Hypoglycemic Agents; D012265:Ribonucleotides; D000620:Aminoimidazole Carboxamide; C031143:AICA ribonucleotide
keywords: AICAR; db/db mice; exercise; tear secretion