Volume 91, Issue 2, February (2004), pp. 227-234 © The Author 2004
doi:10.1079/BJN20031044

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Dietary-induced changes in the fatty acid profile of rat pancreatic membranes are associated with modifications in acinar cell function and signalling

Maria D. Yago¹, Ricardo J. Diaz¹, Rolando Ramirez¹, Maria A. Martinez¹, Mariano Mañas¹, Emilio Martinez-Victoria^1
1Institute of Nutrition and Food Technology, Department of Physiology, University of Granada, C/ Ramon y Cajal 4, 18071 , Granada, Spain

 (Received 6 May 2003–Revised 27 September 2003–Accepted 8 October 2003)

The effects of dietary lipids on the fatty acid composition of rat pancreatic membranes and acinar cell function were investigated. Weaning rats were fed for 8 weeks on one of two diets which contained 100 g virgin olive oil (OO) or sunflowerseed oil (SO)/kg. Pancreatic plasma membranes were isolated and fatty acids determined. Amylase secretion and cytosolic concentrations of Ca²⁺ and Mg²⁺ were measured in pancreatic acini. Membrane fatty acids were profoundly affected by the diets; the rats fed OO had higher levels of 18 : 1n-9 (42·86 (sem 1·99) %) and total MUFA compared with the animals fed SO (25·37 (sem 1·11) %). Reciprocally, the SO diet resulted in greater levels of total and n-6 PUFA than the OO diet. The most striking effect was observed for 18 : 2n-6 (SO 17·88 (sem 1·32) %; OO 4·45 (sem 0·60) %), although the levels of 20 : 4n-6 were also different. The proportion of total saturated fatty acids was similar in both groups, and there was only a slight, not significant (P=0·098), effect on the unsaturation index. Compared with the OO group, acinar cells from the rats fed SO secreted more amylase at rest but less in response to cholecystokinin octapeptide, and this was paralleled by reduced Ca²⁺ responses to the secretagogue. The results confirm that rat pancreatic cell membranes are strongly influenced by the type of dietary fat consumed and this is accompanied by a modulation of the secretory activity of pancreatic acinar cells that involves, at least in part, Ca²⁺ signalling.

Keywords:
Dietary fat, Pancreatic acini, Membrane fatty acids, Cholecystokinin, Calcium signalling

Abbreviations:
BSA, bovine serum albumin, CCK-8, cholecystokinin octapeptide, cPLA2, cytosolic Ca²⁺-dependent phospholipase A₂, IP3, inositol trisphosphate, PLC, phospholipase C, PSS, physiological salt solution, SFA, saturated fatty acids, UI, unsaturation index