In Vivo Electrochemical Detection of Serotonin in Murine Anorectum

Lower bowel dysfunction affects around 20 % of the population. Although there are multiple risk factors for lower bowel dysfunction, the major contributors are the natural ageing process and dementia. Serotonin (5-HT) is released from enterochromaffin cells within the mucosal epithelium and plays a key role in driving motility. Ex vivo studies have shown changes in 5-HT levels within the anorectum could explain changes associated with lower bowel dysfunction. Our study aimed to develop an in vivo anorectum sensor that could monitor changes in 5-HT levels with age and Alzheimer's.
The electrochemical sensor was made using a dual extruder 3D printer using multiwall carbon nanotubes/polylactic acid (MWCNT/PLA) to make the electrodes. To make the reference electrode, the electrode was painted with silver paint. The electrochemical sensor was made in a diameter that could be inserted into the anus to monitor levels of 5-HT from the anorectum.
The electrochemical sensor was fully characterised initially using redox probes and then for sensitivity and selectivity for 5-HT measurements within the anorectum. Measurements were made in mice aged between 12 to 18 months old and in APP/PS1 mice (model for Alzheimer’s disease). We have successfully characterised and detected serotonin in the murine anorectum in vivo and showed changes with age. This study may provide invaluable insight into how changes in serotonin signalling may contribute to lower bowel dysfunction.