Inositol 1,4,5-trisphosphate formation, cytoplasmic calcium dynamics, and alpha-amylase secretion of pancreatic acini isolated from aged and chronically alcohol-fed rats.
METHODS
Three-month-old female Wistar rats were fed with 20% alcohol in their drinking fluid over 6-17 mo using an interrupted feeding regimen. At different times, pancreatic acini were isolated by mild collagenase digestion. The concentrations of inositol-1,4,5-trisphosphate (1,4,5-IP3) were determined by a specific radioreceptor assay, before and at different times after stimulation with varying concentrations of CCK-8. CCK-induced dynamics of cytoplasmic calcium ([Ca2+]c) was investigated in acinar cells by confocal laser raster microscopy. Acinar alpha-amylase (Aml) secretion was measured as enzyme activity in the medium compared to the total activity in the suspension.


RESULTS
In 12-13-mo-old rats, the CCK-stimulated 1,4,5-IP3 formation in acini was found to be decreased compared to young rats (age 4 mo). In rats of the same age fed with ethanol from the age of 3 mo on, 1,4,5-IP3 concentrations in acini were higher and reached values comparable to those in young rats. Correspondingly, the CCK-induced [Ca2+]c dynamics in acini isolated from 9-mo-old rats was impaired compared to that of young rats but normal in aged, chronically alcohol-fed rats. Aml secretion under CCK stimulation, however, which was decreased in aged rats, was additionally impaired after alcohol feeding.


CONCLUSIONS
Chronic alcohol feeding modifies 1,4,5-IP3 formation, the [Ca2+]c dynamics of, and the Aml secretion of rat pancreatic acini in response to CCK stimulation. Obviously, the age-related impairment of 1,4,5-IP3 formation and [Ca2+]c dynamics is improved. In contrast, the decrease in Aml secretion of acini isolated from aged rats is more pronounced after long-term alcohol-feeding.
Siegmund
E
E
Institute of Clinical Chemistry and Pathobiochemistry, Faculty of Medicine, University of Rostock, Germany. eva.siegmund@med.uni-rostock.de
Pommerenke
H
H
Jonas
L
L
Nizze
H
H
Höllerich
I
I
Röhring
A
A
Schuff-Werner
P
P
D000375:Aging / Q000378:metabolism*; D000437:Alcoholism / Q000201:enzymology / Q000378:metabolism*; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D003593:Cytoplasm / Q000378:metabolism; D005260:Female; D066298:In Vitro Techniques; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis*; D010179:Pancreas / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012844:Sincalide / Q000494:pharmacology; D000516:alpha-Amylases / Q000378:metabolism*
D015544:Inositol 1,4,5-Trisphosphate; D000516:alpha-Amylases; D012844:Sincalide