Flow cytometric analysis of BrdU incorporation as a high-throughput method for measuring adult neurogenesis in the mouse.
BACKGROUND
The generation of new neurons occurs throughout adulthood in discrete brain regions, and may be regulated by neuropsychiatric diseases and therapeutic drug treatments. Most current methods that study this process measure the labeling of newborn cells by 5-bromo-2-deoxyuridine (BrdU) using immunohistochemical methods followed by the microscopic counting of BrdU positive cells. This method is time consuming and labor intensive, typically taking several weeks to analyze.


METHODS
Therefore, we characterized a method to measure BrdU incorporation in the adult mouse hippocampus in vivo by using flow cytometry, which normally allows analysis of data within a single day.


RESULTS
The present study compared multiple BrdU dosing and loading protocols to determine a dosing strategy that produced the best signal to noise ratio. BrdU incorporation was also compared across different brain regions. The method was sensitive to a number of experimental disease manipulations. Induction of type-1 diabetes and depletion of norepinephrine reduced hippocampal cell proliferation. In contrast, chronic administration of electroconvulsive shock, a somatic treatment for depression, as well as chronic treatment with the antidepressant fluoxetine elevated hippocampal cell proliferation. This increase in cell proliferation with fluoxetine was detected as early as 14 days into treatment. Moreover, comparing measures of cell proliferation obtained by immunohistochemical and flow cytometric methods within the same animals were convergent and significantly correlated to each other. Flow cytometry was also sufficiently sensitive to quantify the survival of newly born cells.


CONCLUSIONS
These experiments validate the utility of flow cytometry in analyzing hippocampal cell proliferation and survival in a reliable and high-throughput fashion. The speedy analysis afforded by flow cytometry lends itself to be utilized in novel drug discovery and physiology.
Balu
Darrick T
DT
Department of Pharmacology, University of Pennsylvania, Philadelphia, PA 19104, USA.
Hodes
Georgia E
GE
Hill
Tiffany E
TE
Ho
Nancy
N
Rahman
Zia
Z
Bender
Corey N
CN
Ring
Robert H
RH
Dwyer
Jason M
JM
Rosenzweig-Lipson
Sharon
S
Hughes
Zoe A
ZA
Schechter
Lee E
LE
Lucki
Irwin
I
D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology; D001596:Benzylamines / Q000633:toxicity; D001921:Brain / Q000378:metabolism; D001973:Bromodeoxyuridine / Q000032:analysis* / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003921:Diabetes Mellitus, Experimental / Q000139:chemically induced*; D005434:Flow Cytometry / Q000379:methods*; D005473:Fluoxetine / Q000494:pharmacology; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D007150:Immunohistochemistry; D051379:Mice; D008810:Mice, Inbred C57BL; D008815:Mice, Inbred Strains; D055495:Neurogenesis / Q000502:physiology*; D009474:Neurons / Q000187:drug effects; D009498:Neurotoxins / Q000633:toxicity; D009638:Norepinephrine / Q000378:metabolism; D016548:Prosencephalon / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology; D013234:Stem Cells / Q000187:drug effects; D013997:Time Factors
D000928:Antidepressive Agents; D001596:Benzylamines; D001973:Bromodeoxyuridine; D005473:Fluoxetine; D009498:Neurotoxins; D009638:Norepinephrine; D017367:Selective Serotonin Reuptake Inhibitors; C012102:DSP 4