Madison Brockman, Jaspreet K. Rishi, Kelsey Timme, Aileen F. Keating

Department of Animal Science, Iowa State University, Ames IA 50011


Abstract Text:

During obesity, intestinal integrity is compromised, thus elevated systemic lipopolysaccharide (LPS), known as metabolic endotoxemia, is observed. Toll-like receptor 4 (TLR4) is bound by LPS, and LPS is detoxified by Acyloxyacyl Hydrolase (AOAH). Lean (n = 20) and obese (n = 20) female mice were equally divided and received either corn oil as vehicle control or dimethylbenz[a]anthracene (DMBA; 1 mg/kg) for 7d. There were four experimental groups: Lean control (LC; n = 10), lean DMBA (LD; n = 10), obese control (OC; n = 10) and obese DMBA (OD; n = 10). Protein was isolated from three randomly selected livers and western blotting performed to detect TLR4 and AOAH protein. Appropriately sized bands were identified and densitometric analysis was performed utilizing ImageJ software.  Ponceau S staining was performed to confirm equal protein loading and to normalize specific proteins of interest. The abundance of TLR4 and AOAH protein were analyzed using a two-way ANOVA test with multiple comparisons in GraphPad Prism. Statistical significance was considered at P < 0.05, with a tendency for biologically meaningful change if P < 0.10.  Obesity increased (P < 0.05) hepatic TLR4 protein with no impacts of DMBA exposure on TLR4 level. In addition, AOAH was reduced in livers of obese female mice. In lean mice, exposure to DMBA decreased (P < 0.05) AOAH abundance but this response was absent in the livers of obese mice. Thus, basally, obesity increases hepatic TLR4 but reduces AOAH. In lean mice, a differential impact of DMBA exposure on hepatic AOAH protein abundance exists between lean and obese mice. These findings could translate to altered hepatic function to result in a compromised ovarian-hepatic axis in females. Funded by R01ES030341 from NIEHS and Iowa State University incentive funds.