Chronic alcohol feeding potentiates hormone-induced calcium signalling in hepatocytes
| Autor: | Jan B. Hoek, Victoria L. Prince, Amit Agarwal, Anil Noronha Antony, Mauricette Hilly, Paula J. Bartlett, Laurent Combettes, Lawrence D. Gaspers |
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| Rok vydání: | 2017 |
| Předmět: |
0301 basic medicine
medicine.medical_specialty Ethanol Phospholipase C Physiology chemistry.chemical_element Calcium Inositol trisphosphate receptor Calcium in biology 03 medical and health sciences chemistry.chemical_compound 030104 developmental biology medicine.anatomical_structure Endocrinology chemistry Internal medicine Hepatocyte medicine Inositol Calcium signaling |
| Zdroj: | The Journal of Physiology. 595:3143-3164 |
| ISSN: | 0022-3751 |
| Popis: | Key points Chronic alcohol consumption causes a spectrum of liver diseases, but the pathogenic mechanisms driving the onset and progression of disease are not clearly defined. We show that chronic alcohol feeding sensitizes rat hepatocytes to Ca2+-mobilizing hormones resulting in a leftward shift in the concentration–response relationship and the transition from oscillatory to more sustained and prolonged Ca2+ increases. Our data demonstrate that alcohol-dependent adaptation in the Ca2+ signalling pathway occurs at the level of hormone-induced inositol 1,4,5 trisphosphate (IP3) production and does not involve changes in the sensitivity of the IP3 receptor or size of internal Ca2+ stores. We suggest that prolonged and aberrant hormone-evoked Ca2+ increases may stimulate the production of mitochondrial reactive oxygen species and contribute to alcohol-induced hepatocyte injury. Abstract ‘Adaptive’ responses of the liver to chronic alcohol consumption may underlie the development of cell and tissue injury. Alcohol administration can perturb multiple signalling pathways including phosphoinositide-dependent cytosolic calcium ([Ca2+]i) increases, which can adversely affect mitochondrial Ca2+ levels, reactive oxygen species production and energy metabolism. Our data indicate that chronic alcohol feeding induces a leftward shift in the dose–response for Ca2+-mobilizing hormones resulting in more sustained and prolonged [Ca2+]i increases in both cultured hepatocytes and hepatocytes within the intact perfused liver. Ca2+ increases were initiated at lower hormone concentrations, and intercellular calcium wave propagation rates were faster in alcoholics compared to controls. Acute alcohol treatment (25 mm) completely inhibited hormone-induced calcium increases in control livers, but not after chronic alcohol-feeding, suggesting desensitization to the inhibitory actions of ethanol. Hormone-induced inositol 1,4,5 trisphosphate (IP3) accumulation and phospholipase C (PLC) activity were significantly potentiated in hepatocytes from alcohol-fed rats compared to controls. Removal of extracellular calcium, or chelation of intracellular calcium did not normalize the differences in hormone-stimulated PLC activity, indicating calcium-dependent PLCs are not upregulated by alcohol. We propose that the liver ‘adapts’ to chronic alcohol exposure by increasing hormone-dependent IP3 formation, leading to aberrant calcium increases, which may contribute to hepatocyte injury. |
| Databáze: | OpenAIRE |
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