Acetogenesis does not replace ketogenesis in fasting piglets infused with hexanoate

Area of Science:

• Biochemistry
• Physiology
• Animal Science

Background:

• Acetate's physiological role is unclear in piglets, which are poorly ketogenic.
• Ketogenesis is a major metabolic pathway in many mammals, but its counterpart, acetogenesis, is less understood.
• Piglets exhibit higher plasma acetate levels than ketone bodies, contrasting with patterns seen in rats.

Purpose of the Study:

• To investigate the physiological relevance of acetate in piglets.
• To determine if endogenous acetogenesis increases with mitochondrial fatty acid beta-oxidation.
• To explore the analogy between acetogenesis and ketogenesis in vivo.

Main Methods:

• Continuous infusion of sodium [3H]acetate tracer in fasted piglets.
• Measurement of acetate rate of appearance (Ra) using isotopic tracers.
• Comparison of acetate Ra with and without concurrent hexanoate infusion.

Main Results:

• Plasma acetate concentrations in piglets were significantly higher than ketone bodies.
• Acetate Ra in fasted piglets was 34 +/- 4 micromol/min/kg body weight.
• Hexanoate oxidation negatively impacted acetate Ra, and circulating acetate levels did not significantly change in newborn, suckled, or fasted piglets.

Conclusions:

• Acetate is abundant in piglet blood, supporting its potential physiological importance.
• The lack of increased acetogenesis with fatty acid oxidation challenges the direct analogy to ketogenesis.
• Further research is needed to fully elucidate the role of acetate metabolism in piglets.