Abstract
We have previously shown that dietary red palm oil (RPO) supplementation improves functional recovery in hearts subjected to ischaemia/reperfusion-induced injury. Unfortunately, the cellular and molecular mechanisms responsible for this phenomenon are still poorly understood and no knowledge exists regarding the effects of RPO supplementation on the phosphoinositide 3-kinase (PI3-K) signaling pathway and apoptosis during ischaemia/reperfusion injury. Therefore, the aims of the present study were three fold: (i) to establish the effect of RPO on the functional recovery of the heart after ischaemia/reperfuion injury; (ii) to determine the effect of the PI3-K pathway in RPO-induced protection with the aid of an inhibitor (wortmannin); and (iii) to evaluate apoptosis in our model. Wistar rats were fed a standard rat chow control diet or a control diet plus 7 g RPO/kg for six weeks. Hearts were excised and mounted on a Langendorff perfusion apparatus. Mechanical function was measured after a 25 min period of total global ischaemia followed by 30 minutes of reperfusion. Hearts subjected to the same conditions were freeze-clamped for biochemical analysis at 10 min during reperfusion to determine the involvement of the PI3-Kinase signaling pathway and apoptosis in our model. Dietary RPO supplementation significantly increased % rate pressure product recovery during reperfusion (71.0 ± 6.3% in control vs 92.36 ± 4.489% in RPO; p < 0.05). The % rate pressure product recovery was significantly reduced when wortmannin was added during perfusion (92.36 ± 4.489% in the RPO group vs 75.21 ± 5.26% in RPO + Wm). RPO + Wm also significantly attenuated PI3-K induction compared with the RPO group (59.2 ± 2.8 pixels in RPO vs 37.9 ± 3.4 pixels in RPO + Wm). We have also demonstrated that PI3-K inhibition induced PARP cleavage (marker of apoptosis) in the hearts during ischaemia/reperfusion injury and that RPO supplementation counteracted this effect.
Highlights
Cardiovascular disease is one of the major causes of death in the Western world
Percentage Rate Pressure Product Recovery (% rate pressure product (RPP)) (Figure 1) red palm oil (RPO)-supplementation caused an increase in % RPP recovery at 10 min during reperfusion when compared with the control group (65.5 ± 6.3% in control vs 93.5 ± 5.2% in RPO; p < 0.05) confirming results in previous similar studies
Poly(ADP-ribose) polymerase RPP (PARP) cleavage was significantly reduced in the RPO+Wn group compared with the control wortmannin group
Summary
Cardiovascular disease is one of the major causes of death in the Western world. It is believed to account for more than 12 million deaths annually [1]. RPO-supplementation caused differential phosphorylation of the MAPKs which were associated with improved functional recovery and reduced apoptosis [3,4]. This indicated that the improved physiological function associated with RPO-supplementation, was due to the cellular signaling effects of RPO, both through the NO-cGMP pathway or the pro-survival Akt pathway. These studies suggest that a combination of carotonoids, lycopene, pro-vitamin E and fatty acids provide more protections than one individual component [5,6,7]
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