Early ketamine exposure results in cardiac enlargement and heart dysfunction in Xenopus embryos.
BACKGROUND
Ketamine is a commonly used clinical anesthetic and a popular recreational drug. However, with the exception of studies about the nervous system, studies about the effect of early ketamine exposure on embryos are rare. Xenopus laevis is a commonly used vertebrate model for assessing teratogenicity. Therefore, we treated Xenopus embryos with ketamine to evaluate its teratogenicity on embryos.


METHODS
Xenopus embryos were treated with ketamine from stages 8 to 21. Embryonic and cardiac morphology were analyzed using living embryo imaging and whole-mount RNA in situ hybridization (WMISH). Heart function was measured by heart rate and ventricular shortening fraction (VSF). The mRNA expression levels of several heart development-related genes were determined by reverse transcription quantitative polymerase chain reaction (RT-qPCR). The protein expression levels of XMLC2, phospho-histone H3 (pH3) and histone H3 were determined by western blot.


RESULTS
Ketamine caused concentration-dependent increases in mortality and shortening of body length. At a dose of 0.5 mg/ml, ketamine exposure resulted in cardiac enlargement as the primary manifestation of several malformations: gut defects, a curved axis and shortened body length. Cardiac cells underwent increased proliferation. Moreover, the heart rate and ventricular shortening fraction were decreased, findings indicative of heart dysfunction. XMLC2 expression levels were down-regulated at stages 28, 32/33, 35/36 and 46.


CONCLUSIONS
Ketamine exposure during early development has teratogenic effects on Xenopus embryos. The heart enlargement and decreased VSF may result from the down-regulation of XMLC2 mRNA and protein levels. These findings provide new insight into the potential fetal defects induced by ketamine exposure during early pregnancy.
Department of Anesthesiology, Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, Key Laboratory of Pediatrics in Chongqing, Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, Chongqing Key Laboratory of Translational Medical Research in Cognitive Development and Learning and Memory Disorders, Chongqing, 400014, PR China.
Ran
R
Guo
Department of Anesthesiology, Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, Key Laboratory of Pediatrics in Chongqing, Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, Chongqing Key Laboratory of Translational Medical Research in Cognitive Development and Learning and Memory Disorders, Chongqing, 400014, PR China.
Guangjian
G
Liu
Department of Anesthesiology, Children's Hospital of Chongqing Medical University, No.136, Zhongshan Er Lu, Yuzhong District, Chongqing City, 400014, PR China.
Min
M
Du
Department of Clinical laboratory, Children's Hospital of Chongqing Medical University, Chongqing, 400014, PR China.
Yu
Y
Shi
Department of Forensic Medicine, College of Basic Medicine, Chongqing Medical University, Chongqing, 400016, PR China.
Pu
P
Jiang
Department of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Boston, MA, 02115, USA.
Xiaoli
X
Liu
Department of Anesthesiology, Children's Hospital of Chongqing Medical University, Ministry of Education Key Laboratory of Child Development and Disorders, Key Laboratory of Pediatrics in Chongqing, Chongqing International Science and Technology Cooperation Center for Child Development and Disorders, Chongqing Key Laboratory of Translational Medical Research in Cognitive Development and Learning and Memory Disorders, Chongqing, 400014, PR China.
Lan
L
Liu
Department of Anesthesiology, Children's Hospital of Chongqing Medical University, No.136, Zhongshan Er Lu, Yuzhong District, Chongqing City, 400014, PR China.
Jianxia
J
Liu
Department of Anesthesiology, Children's Hospital of Chongqing Medical University, No.136, Zhongshan Er Lu, Yuzhong District, Chongqing City, 400014, PR China. xuyingxy3066@126.com.
Ying
Y
Xu
D000367:Age Factors; D000778:Anesthetics, Dissociative / Q000633:toxicity*; D000818:Animals; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004625:Embryo, Nonmammalian / Q000002:abnormalities* / Q000187:drug effects*; D005260:Female; D006321:Heart / Q000187:drug effects* / Q000196:embryology* / Q000254:growth & development; D007649:Ketamine / Q000633:toxicity*; D011247:Pregnancy; D014982:Xenopus laevis
D000778:Anesthetics, Dissociative; D007649:Ketamine
Drug exposure; Heart development; Ketamine; XMLC2; Xenopus laevis