Quantitative changes in adipocyte plasma membrane in response to nutritional manipulations

Area of Science:

• Cell Biology
• Physiology
• Nutritional Science

Background:

• Adipocyte size and plasma membrane quantity are crucial for metabolic regulation.
• Nutritional status significantly impacts adipocyte morphology and function.

Purpose of the Study:

• To investigate the relationship between adipocyte size and plasma membrane quantity.
• To determine the effects of nutritional manipulations (high-fat diet, fasting) on this relationship.

Main Methods:

• Developed a method using 125I-labeled diazotized diiodosulfanilic acid to quantify plasma membrane protein.
• Studied rats aged 50-125 days fed standard, low-fat, or high-fat diets.
• Investigated effects of up to 3-day fasting on adipocyte volume and plasma membrane quantity.

Main Results:

• Adipocyte plasma membrane quantity increased linearly with adipocyte volume, irrespective of growth rate (age or diet).
• Fasting reduced adipocyte volume but resulted in more plasma membrane per cell than predicted by the linear relationship in fed rats.
• High-fat diet or fasting did not alter the protein and lipid composition of the adipocyte plasma membrane.

Conclusions:

• Plasma membrane quantity scales linearly with adipocyte volume in rats under normal and high-fat feeding conditions.
• Fasting leads to a dissociation between adipocyte volume and plasma membrane quantity, suggesting adaptive membrane regulation.
• Adipocyte plasma membrane composition remains stable despite significant changes in cell size and nutritional state.