Microchip vagal pacing reduces food intake and body mass

Morbid obesity is an increasing problem worldwide. In many patients pharmacotherapy is ineffective and these cases are treated by surgery. Different types of gastroplasty and gastric bypasses have been described. However, all of these ablative surgical methods are irreversible and often replace obesity by other disorders. Neuromodulation of vagal activity is a method of inducing significant changes in stomach motility. We developed a pre-programmed microchip able to pace vagal afferent activity by changing current parameters. The aim of our study was to evaluate long-term effects of vagal neuromodulation on food intake and body mass in rabbits.

Twenty-seven healthy male adult New Zealand white rabbits were included into the study and divided into three groups: A, B and C, 9 animals each. Microchips were implanted by laparotomy access. Anesthesia was obtained by continuous intravenous infusion of propofol. Microchips were fixed in the preperitoneal pocket and two electrodes were positioned on the posterior vagus in group A by forward, and in group B by backward pacing. Control group C was sham operated by laparotomy and only vagal nerves preparation was performed. The following parameters were estimated: daily solid food and liquids intake, amount of feces, body mass and heart rate.

Within four weeks after operation body mass in group B had decreased up to 12% (P = 0.029), whereas in group A and C changed to -3% and +2%, respectively. An 87% solid food intake was observed in group A, 60% in group B (P < 0.01), and 143% in group C, compared to preoperative period. No significant differences were observed between groups A, B and C for liquids intake. Total feces weight changes corresponded to solid food intake. Heart rate decreased intraoperatively to 78% and 74% in groups A and B, respectively.

Microchip mediated functional gastroplasty significantly reduces food intake and body mass. Obtained results encourage using similar treatment in morbid obesity human patients. However, further studies are required.