New research suggests the gut is linked to differences in pain tolerance

25 Jul 2022

APC Microbiome Ireland researcher Dr Siobhain O’Mahony. Image: Gerard McCarthy

It is hoped that further research at APC Microbiome Ireland could lead to more effective, gender-specific pain treatments.

New research suggests that specific bacteria in the gut microbiome can lead to differences in pain sensation between men and women.

The study was conducted by a team at APC Microbiome Ireland, the Science Foundation Ireland (SFI) research centre based at University College Cork (UCC) and Teagasc.

While several factors have been identified as potentially playing a role in gender differences when it comes to feeling pain, the underlying factors are not yet fully understood.

The APC Microbiome research looked at whether gut bacteria and critical signalling components have an influence on pain thresholds. It also investigated if the menstrual cycle and hormonal contraceptive use might also play roles for gender differences in pain perception.

In the study, published in Brain, Behavior and Immunity, the APC researchers found the ratio of electrical pain tolerance threshold to pain sensation threshold was significantly lesser in women than men.

The research also suggested that the amount of certain bacteria was linked with pain sensation thresholds and stress hormone levels in women during a specific stage of the menstrual cycle.

In the study, women displayed stronger associations than men between microbiota, stress hormones and inflammatory factors in blood and pain levels. The research also found that hormonal contraceptive use was associated with increased gut permeability markers in blood and specific bacteria in the gut.

It is hoped that further research could lead to more effective, gender-specific pain treatments.

One of the lead researchers, Dr Siobhain O’Mahony of APC Microbiome, said the study is one of the first to highlight the possibility of “individual microbiota targeted therapies”.

“Our research highlights the need to design innovative gender-specific interventions perhaps for all disorders related to the gut microbiota,” O’Mahony added. “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 signalling pathways.”

President of the College of Anaesthesiologists at UCC, Prof George Shorten, said the findings of the study are “novel and exciting” as the associations could improve our understanding of pain states.

“The implication is that maintenance or manipulation of the gut microbiota could positively influence pain perception, thereby offering new intervention targets,” Shorten said. “These might include prebiotic or probiotic administration, timing or choice of antibiotics, diet, and fasting protocols for those undergoing surgery.”

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Leigh Mc Gowran is a journalist with Silicon Republic