Reprinted from, Journal of Neuroscience Methods, vol. 115, No 1, Kee, N., Sivalingam, S., Boonstra, R., Wojtowicz, J.M., The Utility of Ki-67 and BrdU as proliferative markers of adult neurogenesis, pp 97-105, 2002, with permission from Elsevier Science
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THE UTILITY OF Ki-67 AND BrdU AS PROLIFERATIVE MARKERS OF ADULT NEUROGENESIS
Kee, N., Sivalingam, S., Boonstra, R., Wojtowicz, J.M.,
Department of Physiology, University of Toronto,
Medical Sciences Building, Toronto, ON Canada M5S 1A8
Abstract:
Adult animals continue to produce new neurons in the dentate gyrus of hippocampus. Until now, the principal method of
studying neurogenesis has been to inject either tritiated thymidine or 5 -Bromo-2-deoxyuridine (BrdU) intraperitoneally followed by
autoradiographic or immunohistochemical detection methods respectively. However, such exogenous markers may produce toxic
effects. Our objective was to determine whether Ki-67, a nuclear protein expressed in all phases of the cell cycle except the resting
phase, can be used as an alternative, endogenous marker. Using immunohistochemistry, we examined Ki-67 and BrdU expression
pattern in rats. Ki-67 was expressed within the proliferative zone of the dentate gyrus and its expression pattern mimicked that of
BrdU when examined soon after exogenous BrdU administration. Quantitative comparison of BrdU and Ki-67-positive cells
showed 50% higher numbers of the latter when examined 24 h after the BrdU injection. This was expected, since BrdU can be
incorporated into DNA only during the S-phase of the mitotic process, whereas Ki-67 is expressed for its whole duration.
Experimental increases (by ischemia) or reductions (by radiation) in the number of mitotic cells produced parallel changes in BrdU
and Ki-67 signals. Thus, Ki-67 is an effective mitotic marker and has most of the benefits of BrdU and none of the costs. This study
provides evidence for Ki-67 to be used as a marker of proliferation in the initial phase of adult neurogenesis.
© 2002 Elsevier Science B.V. All rights reserved.
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