title: Treadmill Exercise Improves Memory Function Depending on Circadian Rhythm Changes in Mice.
abstract: OBJECTIVE
  Exercise enhances memory function by increasing neurogenesis in the hippocampus, and circadian rhythms modulate synaptic plasticity in the hippocampus. The circadian rhythm-dependent effects of treadmill exercise on memory function in relation with neurogenesis were investigated using mice.
  
  
  METHODS
  The step-down avoidance test was used to evaluate short-term memory, the 8-arm maze test was used to test spatial learning ability, and 5-bromo-2'-deoxyuridine immunofluorescence was used to assess neurogenesis. Western blotting was also performed to assess levels of synaptic plasticity-associated proteins, such as brain-derived neurotrophic factor, tyrosine kinase receptor B, phosphorylated cAMP response element-binding protein, early growth response protein 1, postsynaptic density protein 95, and growth-associated protein 43. The mice in the treadmill exercise at zeitgeber 1 group started exercising 1 hour after sunrise, the mice in the treadmill exercise at zeitgeber 6 group started exercising 6 hours after sunrise, and the mice in the treadmill exercise at zeitgeber 13 group started exercising 1 hour after sunset. The mice in the exercise groups were forced to run on a motorized treadmill for 30 minutes once a day for 7 weeks.
  
  
  RESULTS
  Treadmill exercise improved short-term memory and spatial learning ability, and increased hippocampal neurogenesis and the expression of synaptic plasticity-associated proteins. These effects of treadmill exercise were stronger in mice that exercised during the day or in the evening than in mice that exercised at dawn.
  
  
  CONCLUSIONS
  Treadmill exercise improved memory function by increasing neurogenesis and the expression of synaptic plasticity-associated proteins. These results suggest that the memory-enhancing effect of treadmill exercise may depend on circadian rhythm changes.
authors.affiliation: Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Dong Sup
authors.identifier: 0000-0002-3540-3323
authors.initials: DS
authors.lastname: Hwang
authors.affiliation: Department of Kinesiology, Inha University, Incheon, Korea.
authors.forename: Hyo Bum
authors.identifier: 0000-0003-0451-4554
authors.initials: HB
authors.lastname: Kwak
authors.affiliation: Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Il Gyu
authors.identifier: 0000-0003-2696-6869
authors.initials: IG
authors.lastname: Ko
authors.affiliation: Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Sung Eun
authors.identifier: 0000-0003-3742-0271
authors.initials: SE
authors.lastname: Kim
authors.affiliation: Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Jun Jang
authors.identifier: 0000-0001-5594-5915
authors.initials: JJ
authors.lastname: Jin
authors.affiliation: Department of Physiology, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Eun Sang
authors.identifier: 0000-0001-6135-7183
authors.initials: ES
authors.lastname: Ji
authors.affiliation: Division of Leisure & Sports Science, Department of Exercise Prescription, Dongseo University, Busan, Korea.
authors.forename: Hyun Hee
authors.identifier: 0000-0002-8556-0044
authors.initials: HH
authors.lastname: Choi
authors.affiliation: Department of Medical Education and Medical Humanities, College of Medicine, Kyung Hee University, Seoul, Korea.
authors.forename: Oh Young
authors.identifier: 0000-0003-0817-2256
authors.initials: OY
authors.lastname: Kwon
keywords: Exercise Test; Learning; Memory, Short-term; Neurogenesis; Neuronal Plasticity