Influences of transcutaneous neuromodulation on fecal microbiota and short chain fatty acids in patients with functional constipation.

Fecal microbiota richness and diversity were both increased in FC patients compared to healthy controls at baseline.

• Fourteen FC patients were recruited and compared to healthy controls
• Both richness and diversity metrics were elevated in FC patients before TN treatment
• Samples were collected before and after 4-week TN treatment
• This finding was observed at baseline prior to any intervention

Branched-chain SCFAs were elevated in FC patients compared to healthy controls at baseline.

• Fecal metabolomic differences between FC patients and healthy controls were observed at baseline
• Specifically elevated branched-chain SCFAs included isobutyric, isovaleric, and valeric acids in FC patients
• Blood and fecal samples were collected to assess fecal microbiome and SCFAs
• These differences were present prior to TN treatment

TN treatment did not significantly alter SCFA levels in FC patients.

• SCFA levels were assessed before and after 4 weeks of TN treatment
• No significant changes in SCFAs were detected following TN treatment
• Despite lack of SCFA changes, constipation symptoms were improved
• Plasma 5-HT was increased despite unchanged SCFAs

TN treatment improved constipation symptoms and increased plasma 5-HT levels in FC patients.

• FC-related symptoms were evaluated by questionnaires before and after 4-week TN treatment
• Plasma 5-HT expression levels were significantly increased after TN treatment
• The study involved 14 FC patients undergoing 4 weeks of transcutaneous neuromodulation
• Both symptomatic and biochemical improvements were observed

A significant correlation between Blautia-serotonin and plasma 5-HT was present in FC patients before TN treatment but disappeared after treatment.

• Before TN treatment, correlation between Blautia-serotonin and 5-HT was r = 0.574, P = 0.035
• After TN treatment, the correlation was no longer significant: r = 0.160, P = 0.584
• This change in correlation suggested a potential interaction between 5-HT changes caused by TN and dynamic changes of intestinal microbiota
• The correlation was assessed in the 14 FC patients at both timepoints