Gene expression analysis of liver and kidney following methapyrilene treatment in male Sprague-Dawley rats

This study was performed to gain insight into the hepatotoxicity of methapyrilene. Gene expression changes in the kidney (non-target tissue for toxicity) were compared to those in the liver (target tissue for toxicity) to attribute gene expression changes to relevant biological processes (i.e. toxic response, non-specific acute response, pharmacological response, etc…). Keywords: Time course, tissue comparison, liver toxicity, hepatotoxicity Male Sprague-Dawley rats were treated with methapyrilene at two different doses (10 mg/kg/day and 100 mg/kg/day) for 1, 3, and 7 days. Livers and kidneys were removed 24 hours after the last dose and flash frozen in liquid nitrogen. Five hundred nanograms (500 ng) of total RNA was amplified and labeled using the Agilent Low RNA Input Fluorescent Linear Amplification Kit according to the manufacturer’s protocol. For each two color comparison, 750 ng each of Cy3- and Cy5-labeled cRNA were mixed and fragmented using the Agilent In Situ Hybridization Kit protocol. Hybridizations were performed for 17 hours in a rotating hybridization oven according to the Agilent 60-mer oligo microarray processing protocol prior to washing and scanning with an Agilent Scanner. Data was obtained using the Agilent Feature Extraction software (v. 7.1) using defaults for all parameters. Equal amounts of RNA was pooled from all of the animals in each group (n=4). Each treated group was hybridized against its pooled time-matched and tissue-matched control group in quadruplicate (2 replicates + 2 fluor reversals).