Visceral pain is a prevalent symptom affecting >20% of the global population. Notably, chronic visceral pain is typically accompanied by concomitant symptoms such as abdominal distension, diarrhoea and/or constipation. Nociceptors (i.e., the nervous system’s pain-sensing neurons) have been recognised as “bidirectional signalling machines” that, in addition to transmitting noxious signals to the spinal cord, can modulate peripheral tissue physiology. Hence, abnormal activation of gut nociceptors might not only be linked to the development of chronic pain but also to its associated symptoms.

First, I will discuss the mechanisms underlying chronic visceral pain. We recently identified a peripheral mechanism behind food-induced abdominal pain following a bacterial infection that involves intestinal neuro-immune interactions. Now, we expanded these findings and discovered that psychological stress can also lead to food-evoked visceral pain by interfering with the gut immune system.

Secondly, I will delve into the biological function of nociceptors as a protective entity. We found that activation of nociceptors by harmful irritants triggers the epithelium to secrete electrolytes/water into the lumen, therefore contributing to expelling these irritants from the body. This highlights the protective role of (gut) nociceptors beyond their usual ‘ouch’ response and suggests that an aberrant activation could ultimately cause diarrhoea.

More information:

• https://www.phar.cam.ac.uk/staff/dr-javier-aguilera-lizarraga