L‐glutamine and palmitate catabolism in pancreatic islets from rats depleted in long‐chain polyunsaturated ω3 fatty acids

Abstract

The catabolism of D-glucose was recently found to be impaired in pancreatic islets from rats depleted in long-chain polyunsaturated omega3 fatty acids. The specificity of this alteration was now investigated by characterizing the oxidative fate of endogenous nutrients in islets preincubated with either L-[U-14C]glutamine or [U-14C]palmitate and then incubated variously in the absence of D-glucose, presence of the hexose or presence of metabolic poisons. Relative to their radioactive content after preincubation, the production of 14CO2 by islets prelabelled with [U-14C]glutamine was higher in omega3-depleted rats than control animals. The enhancing action of D-glucose upon such production was impaired, however, in the omega3-depleted rats. The net uptake of 14C-palmitate and absolute value for 14CO2 output were both increased in omega3-depleted rats, whilst the ratio between 14CO2 output and islet radioactive content was decreased in the same animals. The inhibition of 14CO2 production by metabolic poisons was comparable in all cases. These results are consistent with recent findings on such items as the availability of endogenous amino acids and uptake of unesterified fatty acids in extrapancreatic sites of the omega3-depleted rats. They also support the view that the alteration of D-glucose metabolism in the islets of the latter animals may be attributable, in part at least, to alteration of glucokinase kinetics by high intracellular acyl-CoA levels.

Long‐chain fatty acyl‐coenzyme A‐induced inhibition of glucokinase in pancreatic islets from rats depleted in long‐chain polyunsaturated ω3 fatty acids

“…[1][2][3] The relative magnitude of the increase in D- [5-3 H]glucose utilization by islets exposed to a rise in the extracellular concentration of the hexose is indeed less pronounced in v3-depleted rats than in control animals. 1 Moreover, at all concentrations of D-glucose, the ratio between D-[U-…”

In vivomonitoring of intracellular Ca2+dynamics in the pancreatic β-cells of zebrafish embryos

“…In mammalian β-cells, excitation occurs not only in response to glucose but also to various other stimuli. [46][47][48][49] To test whether amino acids and free fatty acids contribute to [Ca 2+ ] i signalling of zebrafish pancreatic islets, perfusion experiments with L-glutamine and palmitic acid on extracted islets were carried out. Whole islets extracted from 5 dpf zebrafish larvae showed increase in GCaMP6s FIU/FIU baseline intensity when 20 mM L-glutamine or 1 mM palmitic acid alone and no glucose was applied in the perfusion system ( Figure 5(A,B)).…”

Direct effects of eicosapentaenoic and docosahexaenoic acids on phospholipid and triglyceride fatty acid pattern, glucose metabolism, 86rubidium net uptake and insulin release in BRIN-BD11 cells

“…The long-term effects of a dietary deprivation of longchain polyunsaturated x3 fatty acids on enzymatic [1], metabolic [2,3], ionic [4][5][6], and secretory [2,[4][5][6] variables in isolated pancreatic islets were recently investigated in second-generation x3-depleted rats. Extrapancreatic events including insulin resistance [2,7], liver steatosis [8,9], and visceral obesity [10] were also documented in these second-generation x3-depleted rats, and confirmed in normal rats exposed seven weeks after birth for 3-7 months to an x3-depleted diet [11].…”

“…(±SEM) refer to3 separate determinations in all casesThe statistical indices (a: P \ 0.05; c: P \ 0.02; d: P \ 0.01; e: P \ 0.005; f: P \ 0.001) refer to the differences between control and x3-enriched cells (second and third columns) or to the deviation from 100% of the percentages listed in the an absolute amount represented in the x3-enriched cells 229.6 ± 41.2% (n = 15; P \ 0.01) of the paired value found, within the same experiment, in the control cells. A small amount of C24:0 was, on occasion, detected in the triglycerides of x3-enriched cells.…”