Ketamine alters the neurogenesis of rat cortical neural stem progenitor cells.
OBJECTIVE
High doses or prolonged exposure to ketamine increase neuronal apoptosis in the developing brain, although effects on neural stem progenitor cells remain unexplored. This study investigated dose- and time-dependent responses to ketamine on cell death and neurogenesis in cultured rat fetal cortical neural stem progenitor cells.


METHODS
Laboratory-based study.


METHODS
University research laboratory.


METHODS
Sprague-Dawley rats.


METHODS
Neural stem progenitor cells were isolated from the cortex of Sprague-Dawley rat fetuses on embryonic day 17. In dose-response experiments, cultured neural stem progenitor cells were exposed to different concentrations of ketamine (0-100 µM) for 24 hrs. In time-course experiments, neural stem progenitor cells cultures were exposed to 10 µM ketamine for different durations (0-48 hrs).


RESULTS
Apoptosis and necrosis in neural stem progenitor cells were assessed using activated caspase-3 immunostaining and lactate dehydrogenase assays, respectively. Proliferative changes in neural stem progenitor cells were detected using bromo-deoxyuridine incorporation and Ki67 immunostaining. Neuronal differentiation was assessed using Tuj-1 immunostaining. Cultured neural stem progenitor cells were resistant to apoptosis and necrosis following all concentrations and durations of ketamine exposure tested. Ketamine inhibited proliferation with decreased numbers of bromo-deoxyuridine-positive cells following ketamine exposure to 100 µM for 24 hrs (p<.005) or 10 µM for 48 hrs (p< .01), and reduced numbers of Ki67-positive cells following exposure to ketamine concentration>10 µM for 24 hrs (p<.001) or at 10 µM for 48 hrs (p<.01). Ketamine enhanced neuronal differentiation, with all ketamine concentrations increasing Tuj-1-positive neurons (p<.001) after 24-hrs of exposure. This also occurred with all exposures to 10 µM ketamine for >8 hrs (p<.001).


CONCLUSIONS
Clinically relevant concentrations of ketamine do not induce cell death in neural stem progenitor cells via apoptosis or necrosis. Ketamine alters the proliferation and increases the neuronal differentiation of neural stem progenitor cells isolated from the rat neocortex. These studies imply that ketamine exposure during fetal or neonatal life may alter neurogenesis and subsequent brain development.
Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN, USA.
Chaoxuan
C
Dong
Cynthia R
CR
Rovnaghi
K J S
KJ
Anand
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002540:Cerebral Cortex / Q000166:cytology / Q000254:growth & development; D004305:Dose-Response Relationship, Drug; D007649:Ketamine / Q000494:pharmacology*; D058953:Neural Stem Cells / Q000187:drug effects*; D055495:Neurogenesis / Q000187:drug effects*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*; D013997:Time Factors
D016194:Receptors, N-Methyl-D-Aspartate; D007649:Ketamine