LEPR and endothelial dysfunction: Zucker obese and Zucker diabetic fatty rats, which have improper encoding of the leptin receptor gene (manifesting as an impaired satiety reflex, with significant obesity), show progressive impairment of acetylcholine-induced relaxation of coronary microvessels (preceding changes in the aorta), as demonstrated by Oltman et al. There is an improvement when vessels of such rats are incubated with Tiron (a nonspecific free radical scavenger), suggesting reactive oxygen species as a mechanism of endothelial dysfunction [21].