BACKGROUND: It has been increasingly suggested that propofol protects against hypoxic-/ischemic-induced neuronal injury. As evidenced by hemorrhage-induced stroke, hemorrhage into the brain may also cause brain damage. Whether propofol protects against hemorrhage-induced brain damage remains unknown. Therefore, in this study, we investigated the effects of propofol on hemoglobin-induced cytotoxicity in cultured mouse cortical neurons.
METHODS: Neurons were prepared from the cortex of embryonic 15-day-old mice. Hemoglobin was used to induce cytotoxicity in the neurons. The neurons were then treated with propofol for 4 hours. Cytotoxicity was determined by lactate dehydrogenase release assay. Caspase-3 activation was examined by Western blot analysis. Finally, the free radical scavenger U83836E was used to examine the potential involvement of oxidative stress in propofol’s effects on hemoglobin-induced cytotoxicity.
RESULTS: We found that treatment with hemoglobin induced cytotoxicity in the neurons. Propofol enhanced hemoglobin-induced cytotoxicity. Specifically, there was a significant difference in the amount of lactate dehydrogenase release between hemoglobin plus saline (19.84% ± 5.38%) and hemoglobin plus propofol (35.79% ± 4.41%) in mouse cortical neurons (P = 0.00058, Wilcoxon Mann-Whitney U test, n = 8 in the control group or the treatment group). U83836E did not attenuate the enhancing effects of propofol on hemoglobin-induced cytotoxicity in the neurons, and propofol did not significantly affect caspase-3 activation induced by hemoglobin. These data suggested that caspase-3 activation and oxidative stress might not be the underlying mechanisms by which propofol enhanced hemoglobin-induced cytotoxicity. Moreover, these data suggested that the neuroprotective effects of propofol would be dependent on the condition of the brain injury, which will need to be confirmed in future studies.
CONCLUSIONS: These results from our current proof-of-concept study should promote more research in vitro and in vivo to develop better anesthesia care for patients with hemorrhagic stroke.
Published ahead of print January 14, 2016
From the *Key Laboratory of Protein Biochemistry and Developmental Biology of State Education Ministry, College of Life Sciences, Hunan Normal University, Changsha, Hunan, China; †Neuroprotection Research Laboratory, Massachusetts General Hospital, Charlestown, Massachusetts; Departments of ‡Radiology and §Neurology, Massachusetts General Hospital, Charlestown, Massachusetts; ‖Program in Neuroscience, Harvard Medical School, Boston, Massachusetts; ¶Department of Neurology, The Affiliated Hospital of Xuzhou Medical College, Xuzhou, Jiangsu, China; #Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts; and **Massachusetts General Hospital Biostatistics Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
Accepted for publication November 3, 2015.
Published ahead of print January 14, 2016
Funding: This research was supported by R01 GM088801 and R01 AG041274 from the National Institutes of Health, Bethesda, MD; the Investigator-initiated research grant from Alzheimer’s Association, Chicago, IL; and Cure Alzheimer’s Fund, Wellesley, MA (to ZX).
The authors declare no conflicts of interest.
The first two authors contributed equally to this study.
Anesthetic propofol was generously provided by the Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts.
Reprints will not be available from the authors.
Address correspondence to Zhongcong Xie, MD, PhD, Geriatric Anesthesia Research Unit, Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, 149, 13th St., Room 4310, Charlestown, MA 02129. Address e-mail to firstname.lastname@example.org; Shuanglin Xiang, PhD, Key Laboratory of Protein Chemistry and Developmental Biology of State Education Ministry, College of Life Science, Hunan Normal University, Changsha 410081, Hunan, China. Address e-mail to email@example.com.