Mechanisms of catecholamine effects on ketogenesis

Area of Science:

• Metabolic regulation
• Endocrinology

Background:

• Ketogenesis is a metabolic process producing ketone bodies.
• Regulation occurs at multiple sites, including lipolysis and hepatic processing of fatty acids.

Purpose of the Study:

• To investigate the control sites of ketogenesis.
• To determine the role of catecholamines in regulating ketogenesis in humans and rats.

Main Methods:

• Infusion studies in humans with epinephrine, norepinephrine, somatostatin, and dopamine.
• Studies using perfused liver or hepatocytes.
• Infusion studies in rats.

Main Results:

• In humans, epinephrine and norepinephrine increase plasma nonesterified fatty acids (NEFA), glycerol, and ketone bodies.
• Catecholamine effects on ketogenesis are minimal in perfused liver/hepatocytes.
• Rat studies showed decreased ketogenesis with catecholamine infusion.
• Somatostatin potentiates catecholamine-induced lipolysis and ketogenesis.

Conclusions:

• Catecholamine-induced ketogenesis in humans is primarily driven by increased NEFA substrate supply from adipose tissue.
• Species differences exist in the regulation of ketogenesis.
• The liver's direct response to catecholamines for ketogenesis is limited.