Voluntary wheel running in mice increases the rate of neurogenesis without affecting anxiety-related behaviour in single tests.
BACKGROUND
The role played by adult neurogenesis in anxiety is not clear. A recent study revealed a surprising positive correlation between increased anxiety and elevated neurogenesis following chronic voluntary wheel running and multiple behavioural testing in mice, suggesting that adult hippocampal neurogenesis is involved in the genesis of anxiety. To exclude the possible confounding effect of multiple testing that may have occurred in the aforementioned study, we assessed (1) the effects of mouse voluntary wheel running (14 vs. 28 days) on anxiety in just one behavioural test; the open field, and (2), using different markers, proliferation, differentiation, survival and maturation of newly born neurons in the dentate gyrus immediately afterwards. Effects of wheel running on anxiety-related behaviour were confirmed in a separate batch of animals tested in another test of anxiety, the light/dark box test.


RESULTS
Running altered measures of locomotion and exploration, but not anxiety-related behaviour in either test. 14 days running significantly increased proliferation, and differentiation and survival were increased after both running durations. 28 day running mice also exhibited an increased rate of maturation. Furthermore, there was a significant positive correlation between the amount of proliferation, but not maturation, and anxiety measures in the open field of the 28 day running mice.


CONCLUSIONS
Overall, this evidence suggests that without repeated testing, newly born mature neurons may not be involved in the genesis of anxiety per se.
Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg/Munich, Germany.
Lillian
L
Garrett
D Chichung
DC
Lie
Martin
M
Hrabé de Angelis
Wolfgang
W
Wurst
Sabine M
SM
Hölter
D000704:Analysis of Variance; D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D064026:Calbindins; D002452:Cell Count; D002454:Cell Differentiation / Q000502:physiology; D049109:Cell Proliferation; D003623:Dark Adaptation / Q000502:physiology; D018891:Dentate Gyrus / Q000166:cytology / Q000502:physiology; D000089622:Doublecortin Domain Proteins; D005106:Exploratory Behavior / Q000502:physiology; D019394:Ki-67 Antigen / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009043:Motor Activity / Q000502:physiology; D055495:Neurogenesis / Q000502:physiology*; D009479:Neuropeptides / Q000378:metabolism; D010805:Physical Conditioning, Animal; D012044:Regression Analysis; D012420:Running / Q000502:physiology*; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D013997:Time Factors
D064026:Calbindins; D000089622:Doublecortin Domain Proteins; D019394:Ki-67 Antigen; D008869:Microtubule-Associated Proteins; D009479:Neuropeptides; D064030:S100 Calcium Binding Protein G; D001973:Bromodeoxyuridine