Cellular and behavioral effects of cranial irradiation of the subventricular zone in adult mice.
BACKGROUND
In mammals, new neurons are added to the olfactory bulb (OB) throughout life. Most of these new neurons, granule and periglomerular cells originate from the subventricular zone (SVZ) lining the lateral ventricles and migrate via the rostral migratory stream toward the OB. Thousands of new neurons appear each day, but the function of this ongoing neurogenesis remains unclear.


RESULTS
In this study, we irradiated adult mice to impair constitutive OB neurogenesis, and explored the functional impacts of this irradiation on the sense of smell. We found that focal irradiation of the SVZ greatly decreased the rate of production of new OB neurons, leaving other brain areas intact. This effect persisted for up to seven months after exposure to 15 Gray. Despite this robust impairment, the thresholds for detecting pure odorant molecules and short-term olfactory memory were not affected by irradiation. Similarly, the ability to distinguish between odorant molecules and the odorant-guided social behavior of irradiated mice were not affected by the decrease in the number of new neurons. Only long-term olfactory memory was found to be sensitive to SVZ irradiation.


CONCLUSIONS
These findings suggest that the continuous production of adult-generated neurons is involved in consolidating or restituting long-lasting olfactory traces.
Lazarini
Françoise
F
Institut Pasteur, Laboratory for Perception and Memory, Paris, France.
Mouthon
Marc-André
MA
Gheusi
Gilles
G
de Chaumont
Fabrice
F
Olivo-Marin
Jean-Christophe
JC
Lamarque
Stéphanie
S
Abrous
Djoher Nora
DN
Boussin
François D
FD
Lledo
Pierre-Marie
PM
D000818:Animals; D001522:Behavior, Animal / Q000528:radiation effects*; D002552:Cerebral Ventricles / Q000378:metabolism / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000378:metabolism; D009812:Odorants; D009830:Olfactory Bulb / Q000528:radiation effects; D009833:Olfactory Pathways / Q000528:radiation effects; D012903:Smell / Q000528:radiation effects*; D013997:Time Factors