New UCC-led study finds gut microbiome can influence pain thresholds in men and women

A new study carried out by the APC Microbiome Ireland SFI Research Centre has found that the gut microbiome has a role in driving differences in pain sensation between men and women.

The study, led by University College Cork’s (UCC) Dr Siobhain O’Mahony and Professor George Shorten and published in the journal Brain Behaviour and Immunity, found that specific bacteria in the gut are linked to higher pain and stress hormones in women at certain stages of the menstrual cycle and that hormonal contraceptive use is associated with changes to specific bacteria in the gut and gut permeability.

The gut microbiota are acknowledged as playing important roles in our health and disease. The microorganisms within the gut and the metabolites they produce can, directly and indirectly, affect peoples’ brains, including pain signalling pathways.

The study has allowed the investigation into whether the gut microbiota and critical signalling components influence pain thresholds and whether sex, menstrual cycle, and hormonal contraceptive use might also play roles in inter-sex differences in pain perception.

Researchers observed that the pain tolerance threshold/pain sensation threshold ratio was significantly lesser in women than men and that the amount of certain bacteria was linked with pain sensation thresholds and stress hormone levels in women only and during a specific stage of the menstrual cycle.

In comparison with men, women displayed overall stronger associations between microbiota metabolites, stress hormones and inflammatory factors in blood and pain levels. Further, hormonal contraceptive use was associated with increased gut permeability markers in blood and specific bacteria in the gut.

Investigator at APC Microbiome Ireland and Senior Lecturer and Principal Investigator in the Department of Anatomy and Neuroscience at UCC, Dr Siobhain O’Mahony, said: 

This study is one of the first to highlight the novel possibilities for individual microbiota-targeted therapies for gender-specific pain management.

“Our findings support the hypothesis that the gut microbiota may be one of the influencing factors determining the physiological inter-sex differences in pain perception.

“We plan to continue this exciting research to unravel the molecular mechanisms by which specific sex hormones and gut microbes modulate pain signaling pathways." 

President of the College of Anaesthesiologists at UCC Prof George Shorten said that the discovery of important associations between the gut microbiota and somatic pain is “novel and exciting”.