New chemical entities that humans and animals are likely to be exposed to are
tested using various in vitro and in vivo toxicological assays to understand the
potential for harm. The increasing power of in silico analysis in combination with in
vitro techniques is being exploited for the ability to predict in vivo outcomes such as
toxicity, thereby reducing the requirement for animal testing. Previous studies in our
laboratory have found that dietary phenobarbital treatment of rats results in
dysregulation of the hepatic miRNAome, including prominent alteration of the
expression of the miR-200a/b/429 cluster and miR-182/96 cluster. In this thesis I
explore the use of a cell culture system, rat hepatocyte-like B13/H cells, to
interrogate the underlying mechanisms of phenobarbital-mediated toxicity. Through
this model I explore the function of phenobarbital-dysregulated microRNAs to
determine their roles as markers of phenobarbital treatment in the rat. We find that
the B13/H cells provide a useful system for studying the phenobarbital response in
vitro, and how these responses relate to the effects of oral exposure to phenobarbital
in vivo in the rat. In this respect, the B13/H cells appear representative of the rat
response to phenobarbital, which is different to that of the mouse. With a focus on
the phenobarbital-mediated dysregulation of the miR-182/96 cluster, I have explored
the consequences of phenobarbital treatment on the B13/H cell model and related
this to the in vivo effects. The data suggest that these microRNAs appear to control
phenobarbital-mediated perturbation of glycolysis, cell transformation and
methylation patterns.