A new study claims that vagal de-afferentation using capsaicin, the component responsible for the burning sensation of chili peppers, can achieve weight loss, and reduce the risk of obesity-related diseases with fewer side effects when compared to bariatric surgical options.

Researchers at Brigham and Women's Hospital (BWH; Boston, MA, USA) wished to test the impact of disrupting vagal signaling by selective vagal de-afferentation using capsaicin on weight gain and fat content in diet-induced obese male Sprague–Dawley rats; the animals were maintained for 11 months on a high-caloric Western diet. Abdominal visceral fat content was assessed by magnetic resonance imaging (MRI) together with weight of fat pads at harvest. Glucose homeostasis was assessed by fasting blood glucose and HbA1C. Jejunal SGLT1 gene expression was assessed by qPCR and immune blotting, and function by glucose uptake in everted jejunal sleeves.

The results showed that at 11-months, the de-afferented rats weighed 7% less than the sham procedure cohort, and more importantly, they also had an 18% reduction in visceral abdominal fat. There were no changes in blood glucose or glycemic indexes. SGLT1 mRNA, protein, and function were unchanged across all cohorts at 11-months postoperatively. The study was published in the May 2012 issue of Digestive Diseases and Sciences.

“The reduction in visceral fat is particularly important. High visceral fat volume is a marker of obesity and obesity-related diseases, such as diabetes. Preferentially lost visceral fat after vagal de-afferentation highlights the potential for this procedure,” said lead author Ali Tavakkolizadeh, MD, of the BWH department of surgery.

Vagotomy is a surgical procedure that involves removing the vagus nerve, which sends information between the gut and the brain. Vagal de-afferentation also involves the vagus nerve, but rather than removing the nerve completely, capsaicin is used to destroy only the nerve fibers that transport signals from the gut to the brain, leaving intact the nerve fibers that send signals in the opposite direction, from the brain to the gut.

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