Hepatic interoception in health and disease

Area of Science:

• Neuroscience
• Hepatology
• Physiology

Background:

• The liver plays vital roles in metabolism, immunity, and detoxification, communicating bidirectionally with the brain.
• While the gut-brain axis is well-studied, neural communication pathways from the liver to the brain are less understood.
• Existing knowledge gaps exist regarding the specific sites and molecular mechanisms of peripheral sensory transduction in the liver.

Purpose of the Study:

• To investigate the neural and humoral pathways mediating communication between the liver and the brain.
• To identify function-specific sensory and motor components of vagal and spinal pathways accessing the hepatic parenchyma.
• To explore the role of liver-specific signals in regulating brain function and systemic responses.

Main Methods:

• Review of existing literature on liver-brain communication.
• Analysis of proposed neural sensory mechanisms and their limitations.
• Examination of evidence for glucose sensors in the hepatic portal vein.

Main Results:

• Details of peripheral transduction mechanisms for liver-brain neural signaling are generally lacking.
• Controversies exist regarding the selectivity of vagal access pathways and the extent of hepatocyte innervation.
• Significant evidence supports the role of hepatic portal vein glucose sensors in glucose homeostasis and systemic responses.

Conclusions:

• Understanding liver-brain neural and humoral pathways is crucial, especially given rising liver disease rates and their association with mental illness.
• Further research is needed to elucidate hepatocyte-specific signals and their transmission to the brain.
• The contribution of liver sensations to interoceptive self-awareness remains an unexplored area.