Mc. Picinato et al., Soybean- and olive-oils-enriched diets increase insulin secretion to glucose stimulus in isolated pancreatic rat islets, PHYSL BEHAV, 65(2), 1998, pp. 289-294
Islets isolated from rats fed a lipid-enriched diet have shown an impairmen
t of insulin secretion, but there is no available data comparing the effect
of diet containing different dietary fat. This may be important in prevent
ing or facilitating the establishment of diabetes. In this study, the effec
t of diets enriched (10%) with different fatty acids on insulin secretion b
y isolated pancreatic islets was investigated. The sources of the fatty aci
ds tested were: saturated long chain from animal fat (AF), polyunsaturated
from soybean oil (SO), and monounsaturated from olive oil (OL). The results
were compared with those from rats receiving a diet enriched (10%) with a
balanced mixture of fatty acids (the same proportion of AF, SO, and OL). Th
e effect of fat-rich diets on insulin release was tested in vivo by giving
a glucose load (glucose tolerance test-GTT) and in vitro in perfused islets
. The mechanism involved was also examined by measuring Ca-45(2+) and Rb-86
(+) fluxes, GLUT-2 content, and glucose oxidation in isolated islets. A sig
nificant increase of insulin secretion and glucose oxidation without any al
teration of the ionic movements were detected in islets from SO and OL rats
. GLUT-2 content was increased in islets of the OL group but diminished in
AF rats. The results led us to postulate that soybean and olive oils may in
crease the response of insulin secretion to glucose stimulus in pancreatic
islets. (C) 1998 Elsevier Science Inc.