Lung response to oil vapor exposure in rats
The lung response to inhalation exposure to oil vapor particles was investigated in a rat model.  Adult male Sprague-Dawley rats were exposed by whole-body inhalation to air or an aerosol containing oil vapor particles at concentrations of 300 ppm, 6 hours/day for 1 day (shot-term) or 300 ppm, 6 hours/day, 4 days/week for 4 weeks (long-term).  The control and oil vapor exposed rats were euthanized at post-exposure time intervals of 1 and 28 days and lung toxicity determined.  Analysis of bronchoalveolar lavage parameters of toxicity such as lactate dehydrogenase activity, oxidant generation, and inflammation did not reveal any significant lung toxicity in the oil vapor exposed rats.  Approximately 50 genes each were found significantly differentially expressed in both the short- and long-term exposure groups of the rats at the one-day post-exposure time interval. The data obtained from the present study demonstrated that oil vapor inhalation exposure, under the exposure conditions employed in the present study, did not result in any significant lung toxicity in the rats despite the gene expression changes detected. Overall design: The rats were exposed by whole-body inhalation to filtered air or oil vapor particles (300 ppm, 6 hours/day for 1 day or 300 ppm, 6 hours/day, 4 days/week for 4 weeks). At post exposure time intervals of 1 and 28 days, the air and oil vapor exposed rats were euthanized and lung samples (n=6) were used to determine gene expression profiles by RNA sequencing.