Insulin binding and action on bovine adipocytes.

Area of Science:

• Animal science
• Endocrinology
• Cell biology

Background:

• Insulin's role in glucose metabolism is critical.
• Previous research suggested bovine adipocytes might not respond to insulin.

Purpose of the Study:

• To investigate insulin binding and response in bovine adipocytes.
• To clarify conflicting reports on bovine adipocyte insulin sensitivity.

Main Methods:

• Incubation of bovine adipose tissue with insulin.
• Measurement of glucose uptake and pyruvate kinase activity.
• Assessment of [125I]iodoinsulin binding and internalization.

Main Results:

• Insulin stimulated glucose uptake and pyruvate kinase activity in prolonged incubations (EC50 ~0.5 ng/ml).
• Specific insulin binding to adipocytes was observed, exceeding that in rats.
• Bovine adipocytes internalized insulin, leading to receptor downregulation.

Conclusions:

• Bovine adipocytes possess functional insulin receptors and respond to insulin.
• These findings contradict previous reports and highlight insulin's role in bovine adipose tissue.