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Updated: Aug 8, 2026

Roux-en-Y Gastric Bypass Operation in Rats
Published on: June 11, 2012
Effect of gastric bypass on spontaneous growth hormone and ghrelin release profiles
Marcio C Mancini1, Ana P A C Costa, Maria Edna de Melo
1Obesity and Metabolic Syndrome Unit, Endocrinology Service, Hospital das Clínicas, São Paulo University School of Medicine, São Paulo, Brazil. mmancini@usp.br
Objective:
The purpose of this study was to analyze growth hormone (GH) concentrations in obese women before and after Roux-en-Y gastric bypass (RYGBP) and how resulting changes in weight, fat mass, ghrelin levels, and insulin sensitivity affect GH secretion.
Research Methods And Procedures:
Blood was sampled at 20-minute intervals for 24 hours in 10 non-diabetic premenopausal severely obese women before and 6 months after RYGBP. GH concentrations were measured in all samples, and serum ghrelin was collected at five time-points.
Results:
After a 27% BMI drop (55.9 +/- 6.2 to 40.7 +/- 5.8 kg/m2), blunted GH profiles underwent partial recovery. Basal, postprandial, and mean ghrelin concentrations were not changed. A negative correlation was found between mean GH levels and insulin and homeostasis model assessment (p < 0.01). BMI accounted for 54% of GH variation.
Discussion:
Partial recovery of GH secretion after RYGBP-induced weight loss suggests that a blunted secretion is not a causal factor of obesity but a consequence of the obese state and does not seem to be ghrelin-level dependent.
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