Lung toxicity assessment using bronchoalveolar lavage fluid and pleural lavage fluid cytology by intratracheal treatment in rats.

Usefulness of bronchoalveolar lavage fluid (BALF) and pleural cavity lavage fluid (PLF) as an experimental material was evaluated for the assessment of pulmonary toxicity of chemicals in rats. From the viewpoint of safety, isoflurane can be used for euthanasia/anesthesia because there was no difference in biological properties of BALF between diethyl ether and isoflurane. Here, we also recognized phosphate buffered saline (PBS) and distilled water equally as a solvent/vehicle for negative control. PLF is also provided as a useful target material as well as BALF for assessing chemical lung toxicity. To evaluate the method, we used zinc chloride as a model chemical and obtained the expected and satisfied results. We may conclude that the intratracheal treatment and combination usage of BALF and PLF as a target material is a good method for assessment of chemical pulmonary (lung and plural cavity) toxicity in rats.

Gastric mucosal changes induced by polyethylene glycol 400 administered by gavage in rats.

Polyethylene glycol 400 (PEG 400) is widely used with a variety of pharmaceutical formulations, and is often added to dosing formulations in preclinical toxicity studies. The aim of the present study was to characterize the effects of PEG 400 on the rat gastrointestinal tract. Three dosage levels (5, 50 or 100 v/v%) of PEG 400 were administered at a volume of 5 ml/kg/day by gavage for 15 days to the rats (5 males and 5 females in each group). At the end of the treatment, the whole lengths of gastrointestinal tracts were examined pathologically. Although there were no gross abnormalities at necropsy, the histopathological examination revealed several changes localized to the stomach mucosa, but not in the intestine. The changes consisted of infiltration of eosinophils and globule leukocytes, increased in the height of the entire mucosal layer, elongation of the surface mucous epithelial and mucous neck cell layers with increased intracellular mucous in the glandular stomach, and the spongiosis (intercellular edema) of the squamous epithelium in the forestomach. These changes near the limiting ridge tended to increase in severity and extent in a dose-dependent manner. These results suggest that repeated oral administration of concentrated PEG 400 can easily induce the mucosal changes in the stomach of the rats.