Thyroidectomy stimulates glucagon-like peptide-1 secretion and attenuates hepatic steatosis in high-fat fed rats

Area of Science:

• Metabolic research
• Endocrinology
• Obesity research

Background:

• Thyroid hormones (THs) influence metabolism, but their precise role in obesity treatment remains unclear.
• Understanding the mechanisms of TH action is crucial for developing effective obesity interventions.

Purpose of the Study:

• To investigate the metabolic effects of surgically induced hypothyroidism in high-fat diet (HFD) fed rats.
• To elucidate the detailed mechanisms underlying these metabolic changes.

Main Methods:

• Surgical thyroidectomy (Thx) was performed on HFD-fed Sprague Dawley (SD) rats.
• Evaluated body weight, food and water intake, insulin response, lipid profiles, and gene expression.
• Measured circulating and intestinal glucagon-like peptide-1 (GLP-1) levels.

Main Results:

• Hypothyroid rats exhibited decreased body weight, food, and water intake.
• Total cholesterol, HDL, and LDL increased, while serum and hepatic triglycerides decreased.
• Circulating and small intestine GLP-1 expression significantly increased.
• Hepatic expression of lipogenic genes decreased, while beta-catenin and glutamine synthetase were upregulated.
• Gluconeogenic genes (G6P, PCK) expression in the liver was reduced.

Conclusions:

• Surgery-induced hypothyroidism in HFD rats leads to reduced appetite and body weight.
• Increased GLP-1 appears to play a role in mediating these effects, potentially reducing hepatic steatosis.
• These findings suggest hypothyroidism's impact on metabolic regulation and offer insights into potential therapeutic strategies for obesity.