A novel method to detect in vivo oxidant production reveals increased susceptibility to high‐fat diet induced penile oxidative stress in GSNOR knockout mice (LB688)

Excessive production of reactive oxygen species (ROS) has consistently been described as a cause of erectile dysfunction. However, direct measurement of ROS in the penis has remained elusive due to the short half life of ROS and limited accessibility to appropriate tissue beds in humans or animals. Binding of nitric oxide to a cysteine thiol is termed S‐nitrosylation, which can mediate function of many proteins. S‐nitrosylated glutathione reductase (GSNOR) is a major mediator of de‐nitrosylation, which can impact reactive oxygen/nitrogen homeostasis. The objective of this study was to optimize a new technique to measure in vivo ROS production in the mouse penis, and to investigate the effect of a high‐fat diet on penile ROS production in wild type (WT) and GSNOR knockout (KO) mice. WT and GSNOR KO mice were fed a standard chow or high‐fat diet for 3 or 6 weeks (n=3/group). A linear microdialysis probe (3mm membrane, 20kDa cutoff) was inserted into the shaft of the penis of mice under ketamine/xylazine anesthesia, allowing sampling of extracellular fluid. To measure extracellular ROS, probes were perfused with saline containing 100 µM Amplex Ultrared and 1 U/ml horseradish peroxidase. Dialysate fluorescence was measured at the outlet with a Turner Designs (TD‐700) fluorometer at 510Ex/590Em. Mean hydrogen peroxide (H2O2) concentrations were: WT (chow = 0.664, 3wk HFD = 0.666, 6wk HFD = 1.202 µM), GSNOR KO (chow = 0.735, 3wk HFD = 1.349, 6wk = 1.389 µM). Following 3 weeks of HFD, mean penile H2O2 was increased 103% in GSNOR KO vs. WT mice. It can be concluded that lack of GSNOR accelerates the development of oxidative stress in the penis in response to a high‐fat diet. Grant Funding Source : Supported by a trainee grant from the Sexual Medicine Society of North America