Three-Dimensional-Printed Electrochemical Multiwell Plates for Monitoring Food Intolerance from Intestinal Organoids.

Common symptoms of food intolerance are caused by chemical components within food that have a pharmacological activity to alter the motility of the gastrointestinal tract. Food intolerance is difficult to diagnose as it requires a long-term process of eliminating foods that are responsible for gastrointestinal symptoms. Enterochromaffin (EC) cells are key intestinal epithelium cells that respond to luminal chemical stimulants by releasing 5-HT. Changes in 5-HT levels have been shown to directly alter the motility of the intestinal tract. Therefore, a rapid approach for monitoring the impact of chemicals in food components on 5-HT levels can provide a personalized insight into food intolerance and help stratify diets. Within this study, we developed a three-dimensional (3D)-printed electrochemical multiwell plate to determine changes in 5-HT levels from intestinal organoids that were exposed to varying chemical components found in food. The carbon black/poly-lactic acid (CB/PLA) electrodes had a linear range in physiological concentrations of 5-HT (0.1-2 µM) with a limit of detection of 0.07 µM. The electrodes were stable for monitoring 5-HT overflow from intestinal organoids. Using the electrochemical multiwell plate containing intestinal organoids, increases in 5-HT were observed in the presence of 0.1 mM cinnamaldehyde and 10 mM quercetin but reduction in 5-HT levels was observed in 1 mM sorbitol when compared to control. These changes in the presence of chemicals commonly found in food were verified with ex vivo ileum tissue measurements using chromatography and amperometry with boron-doped diamond electrodes. Overall, our 3D electrochemical multiwell plate measurements with intestinal organoids highlight an approach that can be a high-throughput platform technology for rapid screening of food intolerance to provide personalized nutritional diet.

Effects of age and social isolation on murine hippocampal biochemistry and behavior.

Social isolation (SI) is a major health risk in older people leading to cognitive decline. This study examined how SI and age influence performance in the novel object recognition (NOR) and elevated plus maze (EPM) tasks in C57BL/6 mice aged 3 or 24 months. Mice were group-housed (groups of 2-3) or isolated for 2 weeks prior to experimentation. Following NOR and EPM testing hippocampal norepinephrine (NE), 5, hydroxytryptamine (5-HT), 5, hydroxyindole acetic acid (5-HIAA), corticosterone (CORT) and interleukin-6 (IL-6) were determined and serum collected for basal CORT analysis. A separate set of mice were exposed to the forced swim test (FST), sacrificed immediately and serum CORT determined. SI impaired performance in the NOR and the FST, reduced hippocampal 5-HT, increased hippocampal IL-6 and increased serum CORT post-FST in young mice. Aged mice either failed to respond significantly to SI (NOR, FST, hippocampal 5-HT, serum CORT post FST) or SI had synergistic effects with age (hippocampal NE, 5-HIAA:5-HT). In conclusion, the lack of response to SI in the aged mice may affect health by preventing them adapting to new stressors, while the synergistic effects of SI with age would increase allostatic load and enhance the deleterious effects of the ageing process.

Determination of tryptophan metabolism from biological tissues and fluids using high performance liquid chromatography with simultaneous dual electrochemical detection.

Serotonin and kynurenine are formed following metabolism of the essential amino acid tryptophan. Both molecules play important biological roles and the balance of how tryptophan metabolism varies to either the serotonin or kynurenine pathway may provide key insight into the inflammatory status of the biological region. At present complex chromatographic methods are utilised which predominately focus on either monitoring analytes in the serotonin or kynurenine pathway rather than both. Our study develops a simple yet robust methodology for the monitoring of tryptophan metabolism. We utilised isocratic reverse phase high-performance liquid chromatography with simultaneously dual electrochemical detection. This approach allowed for separation of co-eluted analytes and identification of analytes from both pathways within 14 minutes. For all analytes, limits of detection were <35 nM. No crosstalk was observed when dual simultaneous detection was conducted in a radial flow cell. Responses from the hippocampus, blood and ileum mucosa highlighted that each region had a varying ratio of serotonin to kynurenine pathway, indicating varied approaches to tryptophan metabolism. The developed method can monitor how the metabolism of tryptophan varies between the two pathways which can provide insight into the inflammatory state of reach region with age and disease.