Comparing adiposity profiles in three mouse models with altered GH signaling

Area of Science:

• Endocrinology
• Metabolic Research
• Obesity Studies

Background:

• Growth hormone (GH) plays a critical role in regulating body composition and metabolism.
• Understanding GH's influence on adiposity is crucial for metabolic disease research.

Purpose of the Study:

• To investigate the specific role of growth hormone (GH) signaling in regulating adiposity and fat distribution.
• To explore the relationship between GH action, adiposity, and key metabolic hormones like leptin and adiponectin.

Main Methods:

• Utilized three genetically modified mouse lines with altered GH signaling: dwarf GH receptor knockout (GHR -/-), bovine GH antagonist (GHA), and giant bovine GH expressing (bGH).
• Assessed body fat percentage, fat distribution (subcutaneous), food consumption, and serum levels of leptin and adiponectin.

Main Results:

• GHR -/- and GHA mice exhibited increased body fat, primarily subcutaneous. Conversely, bGH mice showed reduced body fat.
• GHA mice had increased food consumption per body weight. Serum leptin was elevated in GHA and decreased in bGH mice.
• Adiponectin levels increased in GHR -/- and GHA mice but decreased in bGH mice, correlating positively with adiposity and negatively with GH function.

Conclusions:

• GH action profoundly influences adiposity, with suppressed signaling leading to increased fat mass and enhanced signaling reducing it.
• Adiponectin levels appear to be a key mediator in GH's effects on adiposity and potentially in GH-induced insulin resistance.
• These findings highlight distinct metabolic consequences of altered GH signaling and suggest a complex interplay with adiponectin.