TNF(alpha) modulation of visceral and spinal sensory processing

Area of Science:

• Neuroscience
• Immunology
• Gastroenterology

Background:

• Cytokine tumor necrosis factor-alpha (TNF(alpha)) is linked to infection responses like fever, fatigue, and malaise.
• These responses indicate central nervous system (CNS) modulation by the immune system.
• TNF(alpha)'s role in CNS control of gastrointestinal function and visceral malaise is under investigation.

Purpose of the Study:

• To investigate the role of TNF(alpha) in the central nervous system (CNS) control of gastrointestinal function.
• To elucidate the mechanisms by which TNF(alpha) influences visceral malaise and related behaviors.

Main Methods:

• Demonstrated TNF(alpha)-induced gastric stasis via dose-dependent interaction with brainstem vago-vagal neurocircuitry.
• Utilized immunohistochemical studies to identify TNF receptor (TNFR1) expression.
• Examined the effects of TNF(alpha) on sensory and efferent elements of the vago-vagal reflex circuit.

Main Results:

• TNF(alpha) induces dose-dependent gastric stasis by engaging vago-vagal neurocircuitry.
• Activation of solitary tract (NST) and area postrema (AP) neurons by TNF(alpha), leading to gastroinhibition via dorsal motor neurons of the vagus (DMN).
• Transient low-dose TNF(alpha) potentiates NST responses, suggesting presynaptic modulation of glutamate release.

Conclusions:

• Constitutive expression of TNFR1 on central vagal and spinal trigeminal afferents, dorsal root ganglia, and spinal cord dorsal horn suggests a mechanism for TNF(alpha)-mediated effects.
• These receptors may explain gastrointestinal dysfunction and tactile hypersensitivity during inflammation or infection.
• TNFR1 may be crucial in chronic pain conditions like allodynia and hyper-reflexia post-injury.