Sleeve gastrectomy and Roux-en-Y gastric bypass alter the gut-brain communication

Area of Science:

• Neuroscience
• Gastroenterology
• Surgical Research

Background:

• Vagal innervation is crucial for gastrointestinal function.
• Bariatric surgeries like VSG and RYGB can impact visceral innervation.
• Understanding the effects of these surgeries on the vagus nerve is essential for patient outcomes.

Purpose of the Study:

• To investigate the anatomical integrity of vagal innervation after VSG and RYGB.
• To assess the impact of these bariatric procedures on vagal neuron survival and hindbrain afferent reorganization.
• To determine if these surgeries induce neuroinflammation in central vagal structures.

Main Methods:

• Used retrograde tracer (fast blue) injected into the stomach to label vagal neurons in nodose ganglion (NG) and dorsal motor nucleus of the vagus (DMV).
• Quantified microglia activation using Iba1 staining in hindbrain sections.
• Studied vagal afferent reorganization with isolectin 4 (IB4) staining and analyzed immunofluorescence density.

Main Results:

• RYGB significantly reduced the number of vagal neurons in NG and DMV compared to controls.
• VSG did not affect vagal neuron numbers but increased vagal afferent density in the nucleus tractus solitarius (NTS).
• RYGB decreased vagal afferent density in the NTS and significantly activated microglia in the NTS and DMV.

Conclusions:

• RYGB, unlike VSG, triggers neuroinflammation in central vagal structures (NTS and DMV).
• RYGB remodels gut-brain communication by reducing vagal neuron populations and altering afferent projections.
• VSG impacts vagal afferent organization without causing significant neuroinflammation in the studied vagal nuclei.