Study of metabolic impact, gene expression alterations and carcinogenesis after surgical intervention for morbid obesity: an experimental study

BACKGROUND: Sleeve gastrectomy (SG) is a gaining ground operation amongst the ones applied for treatment of morbid obesity, consisting of removing the gastric fundus and transforming the stomach into a narrow gastric tube. Though SG is a food limiting operation, the removal of the gastric fundus where ghrelin is mainly produced may indicate a hormonal impact of the procedure. The aim of this experimental study is to create a functional model of SG and to present the long-term weight loss results and the metabolic and hormonal impacts of the procedure. METHODS: For this experimental study male, adult, diet induced obese Wistar rats were used and divided randomly into groups, one submitted to SG and the other to a sham operation. Fasting blood samples were taken before the operation and at the end of the experiment (glucose, plasma lipids, leptin and acylated and des-acyl ghrelin levels were measured). Tissue samples were obtained during the operation and at the end of the experiment, and ghrelin expression was measured with RT-PCR. RESULTS: All animals survived throughout the experiment. After the operation both groups started to lose weight with maximum weight loss on the seventh postoperative day (POD) for the sham-operated group and on the 15th POD for the SG group. Thereafter, both groups started to regain weight but with different rates. By the fourth postoperative week (POW), the average weight of the sham group did not differ statistically significantly compared to the preoperative weight, while after the eighth POW, rats' average weight was statistically significantly increased compared to the preoperative value. On the other hand, average weight of the SG group was lower postoperatively until the end of the study compared to the preoperative average weight. Statistically significant weight loss was achieved comparing the weight progress of the SG group and the sham operation group. Serum leptin levels were significantly reduced in the SG group but not in the sham operation group. Serum acylated ghrelin was not significantly affected in both groups, but a significant decrease was documented in serum des-acyl ghrelin in the SG group. RT-PCR analysis of the gastric fundus documented a significant decrease in the expression of ghrelin in the SG group. No significant pathologies were documented in the animals after examining all tissue samples at the end of the experiment. CONCLUSIONS: SG is a safe operation with promising long term results concerning weight loss. SG affects the serum levels of leptin and des-acyl ghrelin but not the levels of acylated ghrelin in this animal model. Gastric ghrelin secretion seems to be affected after SG. Hepatic ghrelin production is insignificant. Though hormonal changes did occur, the results of weight loss cannot be attributed solely to the hormonal changes and restriction seems to be the dominant mechanism of weight loss