Intraluminal Nutrients Modulate Intracellular Calcium Activity in the Enteric Nervous System of Adult Mice
Bibliographic record
Abstract
Background It has long been hypothesized that enteric neurons are able to detect nutrients present in the intestinal lumen, but direct evidence in intact preparations of the intestine is lacking. Understanding how enteric neurons react to changes in dietary constituents will open new avenues for discoveries on the relation between nutrition, modulation of gut function, and health. Aim To measure neuronal activity in the enteric nervous system in response to luminal nutrients. Methods We have designed chambers allowing us to visualize, record and quantify intracellular calcium activity in 3D live‐cell confocal recordings of neurons from intact, whole thickness segments of mouse intestine. Twenty mice expressing the genetically encoded calcium reporter Gcamp6 under the control of the pan‐neuronal Wnt1 promoter were used to record intracellular calcium activity in neurons from the jejunum and colon, while perfusing different nutrients through the lumen. Krebs solution was perfused as control and Ensure®, 10% Intralipid® or 20mM Glucose were used as stimuli. 3D videos of calcium fluorescence in the neuronal network were acquired with a Nikon A1R confocal microscope and calcium dynamics were analyzed using the Imaris software (Bitplane). Results are expressed as relative changes in fluorescence intensity (ΔF/F) ± SEM among the neuronal populations studied. Results Perfusion of the intestine with Ensure® (liquid meal replacement) increased the fluorescence intensity in reactive neurons by 670 ± 270% in the jejunum and 403 ± 62% in the colon. Peak amplitude was measured on average 5–6 minutes after the initiation of the nutrient perfusion. Perfusion with 10% Intralipid® (lipid emulsion) increased the fluorescence intensity in reactive neurons by 300 ± 180% in the jejunum and 150 ± 15% in the colon. On the other hand, perfusion of the intestine with Glucose (20mM in Krebs solution) lowered baseline fluorescence intensity in a population of neurons by −91 ± 3% in the jejunum and −80 ± 3% in the colon. The percentage of neurons reacting to intraluminal stimuli was dependent on the stimulus and was different between the jejunum and the colon, indicating that subpopulations of neurons might differentially react to different nutrient stimuli. Conclusions We report the existence of slow intracellular calcium changes in the neurons in the intestine that vary depending on the nutrient content of the intestinal lumen. The origin and functional consequences of these changes in intracellular calcium activity as well as the identity of responding neurons are currently under investigation. Support or Funding Information Funding sources: Canadian institutes of Health Research, Alberta Innovates, Human Frontier Science Program. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".