Beneficial Dog Bacteria Up-Regulate Oxytocin and Lower Risk of Obesity

Abstract

Cohabitation with pet dogs imparts diverse health benefits to humans including a slim physique. It is known that neuropeptide hormone oxytocin fundamental in human-canine social bonds regulates appetite and body weight. It was recently shown in mice that consuming Lactobacillus reuteri ATCC 6475 from human breast milk lowers body weight and up-regulates oxytocin levels in blood. Here we test the hypothesis that bacteria from dog saliva may similarly modulate recipient host body weight. We find that a Lactobacillus spp isolate from dog saliva led to lower body weight when fed to C57BL/6 wild type mice. Mice consuming the canineborne L. reuteri also had elevated oxytocin levels in blood plasma, and exhibited body weight in an oxytocin-dependent manner. Interestingly, killed (lysed) canine bacteria were sufficient to achieve the physiological effects. Taken together, these studies provide evidence that dog bacteria modulate oxytocin levels and body weight in recipient mice, and thus may help reduce risk of obesity in individuals cohabitating with pet dogs.