Apoptosis-related genes induced in response to ketamine during early life stages of zebrafish

Toxicol Lett. 2017 Sep 5;279:1-8. doi: 10.1016/j.toxlet.2017.07.888. Epub 2017 Jul 14.

Abstract

Increasing evidence supports that ketamine, a widely used anaesthetic, potentiates apoptosis during development through the mitochondrial pathway of apoptosis. Defects in the apoptotic machinery can cause or contribute to the developmental abnormalities previously described in ketamine-exposed zebrafish. The involvement of the apoptotic machinery in ketamine-induced teratogenicity was addressed by assessing the apoptotic signals at 8 and 24 hpf following 20min exposure to ketamine at three stages of early zebrafish embryo development (256 cell, 50% epiboly and 1-4 somites stages). Exposure at the 256-cell stage to ketamine induced an up-regulation of casp8 and pcna at 8 hpf while changes in pcna at the mRNA level were observed at 24 hpf. After the 50% epiboly stage exposure, the mRNA levels of casp9 were increased at 8 and 24 hpf while aifm1 was affected at 24 hpf. Both tp53 and pcna expressions were increased at 8 hpf. After exposure during the 1-4 somites stage, no meaningful changes on transcript levels were observed. The distribution of apoptotic cells and the caspase-like enzymatic activities of caspase-3 and -9 were not affected by ketamine exposure. It is proposed that ketamine exposure at the 256-cell stage induced a cooperative mechanism between proliferation and cellular death while following exposure at the 50% epiboly, a p53-dependent and -independent caspase activation may occur. Finally, at the 1-4 somites stage, the defence mechanisms are already fully in place to protect against ketamine-insult. Thus, ketamine teratogenicity seems to be dependent on the functional mechanisms present in each developmental stage.

Keywords: Apoptosis; Development; Gene expression; Ketamine; Proliferation; Zebrafish.

MeSH terms

  • Anesthetics, Dissociative / toxicity*
  • Animals
  • Apoptosis / drug effects*
  • Apoptosis / genetics
  • Apoptosis Regulatory Proteins / genetics*
  • Apoptosis Regulatory Proteins / metabolism
  • Blastula / drug effects*
  • Blastula / metabolism
  • Blastula / pathology
  • Cell Proliferation / drug effects
  • Dose-Response Relationship, Drug
  • Gene Expression Regulation, Developmental / drug effects*
  • Ketamine / toxicity*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Risk Assessment
  • Teratogens / toxicity*
  • Time Factors
  • Tumor Suppressor Protein p53 / genetics
  • Tumor Suppressor Protein p53 / metabolism
  • Zebrafish / embryology
  • Zebrafish / genetics*
  • Zebrafish / metabolism
  • Zebrafish Proteins / genetics*
  • Zebrafish Proteins / metabolism

Substances

  • Anesthetics, Dissociative
  • Apoptosis Regulatory Proteins
  • RNA, Messenger
  • Teratogens
  • Tumor Suppressor Protein p53
  • Zebrafish Proteins
  • Ketamine