Chronic Effects of Different Non-esterified Fatty Acids on Pancreatic Islets of Rats

Abstract

The aim of this study was to examine the chronic effects of different non-esterified fatty acids (NEFA) on insulin secretion by pancreatic islets of normal Wistar rats in vitro. Pancreatic islets were isolated from normal Wistar rats, and were incubated with 0.2, 0.4, or 0.8 mmol/L palmitate (C16:0), stearate (C18:0), oleate (C18:1), or linoleate (C18:2) for 24 h, then the insulin secretion and pyruvate dehydrogenase (PDH) activity were examined. Neither islet insulin content nor islet DNA content differed among islets incubated with each kind of NEFA. Compared with control, linoleate significantly inhibited glucose-stimulated insulin secretion (GSIS) and PDH activity at each concentration (p < 0.05), while others inhibited GSIS and PDH activity significantly only at 0.4 and 0.8 mmol/L (p < 0.05). There was no significant difference in GSIS and PDH activity among islets pretreated by palmitate, stearate, and oleate at the same concentration (p > 0.05). However, linoleate decreased GSIS more than others at the same concentration (p < 0.05), while linoleate (0.4 or 0.8 mmol/L) inhibited PDH activity more than others at the same concentration (p < 0.05). Elevation of palmitate, stearate, oleate or linoleate decreases the beta-cell secretory response to glucose, through inhibiting PDH activity. Linoleate exerts more negative effect on GSIS than other NEFA.