LOW-DOSE ALCOHOL REDIRECTS POSTPRANDIAL CHOLINERGIC-STIMULATED APICAL EXOCYTOSIS TO THE BASOLATERAL MEMBRANE IN PANCREATIC ACINAR CELLS, THE SUSCEPTIBILITY MECHANISM OF ALCOHOLIC PANCREATITIS
Bibliographic record
Abstract
Background: We previously demonstrated that alcohol (EtOH) pretreatment of pancreatic acini caused the basal plasma membrane (BPM) to become receptive to aberrant BPM exocytosis upon stimulation with submaximal CCK-8. These actions of alcohol on the acinar cell were due to induction of PM-bound Munc18c to dissociate into the cytosol, rendering the PM Syntaxin4 to interact with PM-SNAP-23 and granule-VAMP to form a complex capable of mediating basolateral exocytosis into the interstitial space, which we had postulated to be a mechanism of alcoholic pancreatitis. Rat pancreas however lacks CCK receptors and instead responds to cholinergic stimulation. Aim: We therefore examined whether 1- low EtOH concentration (20 mM) is able to alter submaximal cholinergic stimulation of rat pancreatic acinar cell secretion and exocytosis; 2- alcohol diet-fed rats are susceptible to develop pancreatitis upon low postprandial cholinergic stimulation. Methods: 1- Dispersed rat pancreatic acini were pretreated with non-stimulatory EtOH (20 mM-1 h) followed by stimulation with postprandial carbachol (3 uM-1 h), a dose stimulating only half maximal amylase secretion; 2- rats were fed with either a control or ethanol (36% of total calories intake replacement) liquid diet for 6 weeks and then challenged with low carbachol (5 ip injections of 0.5 uM/kg/h) stimulation.We then examined: a) PM levels of Munc18c and SNARE proteins, and Munc18c displacement into the cytosol by confocal microscopy and cell subfractionation; b) amylase release; c) real-time epifluorescent imaging of exocytosis using FM1-43; d) electron microscopy to visualize the distribution of granules within the cell; e) tissue hematoxylin and eosin (H&E) staining to examine morphologic changes of pancreatitis; f) serum amylase, lipase and ethanol concentrations as clinical parameters of pancreatitis. Results: 1- a) Whereas 20 mM EtOH has no effect on amylase secretion, pretreatment with 20 mM EtOH inhibited 3 uM carbachol stimulated secretion. b) Whereas 3 uM carbachol evokes apical exocytosis, pretreatment with 20 mM EtOH redirected exocytosis to the basal (by FM1-43 imaging) and lateral plasma membrane (by E.M.). c) While neither 20 mM EtOH nor 3 uM carbachol affected PM-Munc18c (confocal microscopy and subcellular fractionation), pretreatment of acini with 20 mM ETOH induced 3 uM carbachol to displace Munc18c from the BPM into the cytosol. 2-Alcohol diet-fed rats (serum ETOH levels of 20-30 mM) were normal and did not exhibit major morphologic defects in the pancreas. However, subsequent exposure to low-dose carbachol induced mild pancreatitis, observed as altered morphology (E.M and H&E) showing vacuolization in acinar cells, leukocyte infiltrate, hemorrhage and necrotic spots; along with clinical parameters of elevated serum levels of amylase and lipase. These morphologic changes correlated to Munc18c displacement from the BPM and its degradation in the cytosol. Conclusion: Postprandial EtOH renders acini PM-Munc18c conducive for postprandial cholinergic stimulation to displace into the cytosol, relieving Syntaxin4 to bind SNAP-23 and ZG VAMP proteins to promote basolateral exocytosis. We propose this to be a 'susceptibility' mechanism by which alcohol predisposes to human pancreatitis. (Funded by: Alcohol Beverage Medical Research Foundation and NIH -R21 AA015579-01).
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
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 teacher head, 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".