Physiological Responses to Laparoscopic Sleeve Gastrectomy: Focusing on Ghrelin

Laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG) are to bariatric procedure. After both procedures, a changed secretion of hormones from the gastrointestinal tract is believed to affect appetite and glucose metabolism. Studies have shown that after LRYGB, there is a significant increased secretion of GLP-1 and PYY. In contrast, a decreased secretion of ghrelin is a characteristic finding after LSG opposite post-LRYGB, where secretion of ghrelin is reported to be increased, decreased or unchanged. Ghrelin is primarily secreted from the gastric mucosa in the fasting state and decreases in response to food intake. Ghrelin stimulates food intake through appetite-regulating centers in the hypothalamus. Administration of exogenous ghrelin has been reported to stimulate appetite. In addition, ghrelin has recently been suggested also to affect glucose metabolism by inhibition of glucose-stimulated insulin secretion. Therefore the markedly decreased secretion of ghrelin could be of particular important for the decreased appetite and improved glucose tolerance seen after LSG.