PT  - JOURNAL ARTICLE
AU  - Mahalakshmi Shankaran
AU  - Chelsea King
AU  - Jean Lee
AU  - Robert Busch
AU  - Mary Wolff
AU  - Marc K. Hellerstein
TI  - Discovery of Novel Hippocampal Neurogenic Agents by Using an in Vivo Stable Isotope Labeling Technique
AID  - 10.1124/jpet.106.110510
DP  - 2006 Dec 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 1172--1181
VI  - 319
IP  - 3
4099  - http://jpet.aspetjournals.org/content/319/3/1172.short
4100  - http://jpet.aspetjournals.org/content/319/3/1172.full
SO  - J Pharmacol Exp Ther2006 Dec 01; 319
AB  - Neurogenesis occurs in discrete regions of adult mammalian brain, including the subgranular zone of the hippocampus. Hippocampal neurogenesis is enhanced by different classes of antidepressants, but screening for neurogenic actions of novel antidepressants has been inefficient because of limitations of 5-bromo-2′-deoxyuridine labeling techniques. We describe an efficient in vivo method for measuring hippocampal neurogenesis involving incorporation of the stable isotope, 2H, into genomic DNA during labeling with 2H2O (heavy water). Male rodents received 8 to 10% 2H2O in drinking water; DNA was isolated from hippocampal progenitor cells or neurons. Label incorporation into progenitor cells of Swiss-Webster mice revealed subpopulation kinetics: 16% divided with t1/2 of 2.7 weeks; the remainder did not divide over 1 year. Progenitor cell proliferation rates in mice were strain-dependent. Chronic antidepressant treatment for 3 weeks, with 2H2O administered during the final week, increased progenitor cell proliferation across all the strains tested. Fluoxetine treatment increased 2H incorporation into DNA of gradient-enriched neurons or flow-sorted neuronal nuclei 4 weeks after 2H2O labeling, representing the survival and differentiation of newly divided cells into neurons. By screening 11 approved drugs for effects on progenitor cell proliferation, we detected previously unrecognized, dose-dependent enhancement of hippocampal progenitor cell proliferation by two statins and the anticonvulsant topiramate. We also confirmed stimulatory activity of other anticonvulsants and showed inhibition of progenitor cell proliferation by isotretinoin and prednisolone. In conclusion, stable isotope labeling is an efficient, high-throughput in vivo method for measuring hippocampal progenitor cell proliferation that can be used to screen for novel neurogenic drugs.