Hematopoietic Toxicity of Linoleic Acid Anilide: Importance of Aniline

Abstract

The purpose of this study was to investigate the role of hydrolysis products of linoleic acid anilide (LAA), i.e., aniline and lin-oleic acid (LA), in the toxicity to the hemopoietic system, especially to the spleen. To achieve this, the parent compound (LAA) and its putative hydrolysis products, i.e., aniline or linoleic acid (LA), were given to male SD rats at equimolar doses (0.7 mmol/kg) in 0.25 ml mineral oil by gavage, daily, for 14 days. The controls received equal volumes of vehicle only. Five animals from each group were euthanized at Days 1, 7, and 28 following the last dose. At all time points, spleen weights increased in the LAA-and aniline-treated rats, but spleen to body weight ratios were increased only at Days 1 and 7 in these groups. No changes were observed in the LA-treated rats at any time point. RBC counts were decreased in the LAA and aniline groups at Days 1 and 7, whereas hemoglobin content was decreased by 20 and 13% in the LAA-and aniline-treated rats, respectively, only at Day 1. Methemoglobin content in the LAA and aniline groups also increased by 76 and 101%, respectively, at Day 1. Serum transaminases (AST and ALT) decreased in the LAA, aniline, and LA groups but the decreases were more consistent in the LA group. Serum IgA increased in the LAA and aniline groups only at Day 1. Splenic iron content was increased 381, 486, and 51% in the LAA-treated rats and 474, 491, and 58% in the aniline-treated rats at Days 1,7, and 28, respectively. Histopathological changes were confined to the spleen. At Day 1, spleens of both LAA-and aniline-treated rats showed severe vascular congestion and heavy iron deposition. In both groups, vascular congestion diminished by Day 7 and then disappeared by Day 28, although iron deposition within red pulp sinusoids appeared to be unchanged through Day 28. A mild increase in splenic fibrous tissue, which included the capsule, was observed in both LAA and aniline groups at Day 28 only. The similarity in toxic responses of LAA and aniline supports the concept that LAA is hydrolyzed and released aniline is the putative toxin. Further, iron accumulation in the spleens could also contribute to the toxicity through iron-mediated free radical reactions.