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High fructose diet suppresses exercise-induced increase in AQP7 expression in the in vivo rat heart [Anatol J Cardiol]
Anatol J Cardiol. 2016; 16(12): 916-922 | DOI: 10.14744/AnatolJCardiol.2016.6958

High fructose diet suppresses exercise-induced increase in AQP7 expression in the in vivo rat heart

Aziz Karaca1, Orkide Palabıyık2, Ebru Taştekin3, Fatma Nesrin Turan4, Selma Arzu Vardar1
1Departments of Physiology, Faculty of Medicine, Trakya University, Edirne-Turkey
2Biophysics, Faculty of Medicine, Trakya University, Edirne-Turkey
3Pathology, Faculty of Medicine, Trakya University, Edirne-Turkey
4Biostatistics, Faculty of Medicine, Trakya University, Edirne-Turkey

Objective: Cardiac uptake of fructose is thought to be mediated by glucose transporter 5 (GLUT5), whereas the uptake of glycerol is facilitated by aquaporin 7 (AQP7). We aimed to investigate the effect of a high-fructose diet (HFD) on GLUT5 and AQP7 levels in the rat heart subjected to exercise.
Methods: Male Sprague–Dawley rats were allocated to control (C; n=11), exercise (E; n=10), HFD (n=12), and HFD plus exercise (HFD-E; n=12) groups. HFD was started 28 days before euthanasia. From day 24 to 27, rats were subjected to moderate exercise, followed by vigorous exercise on day 28 (groups E and HFD-E). Cardiac GLUT5 and AQP7 mRNA levels were determined using RT-PCR. The protein contents of GLUT5 and AQP7 were immunohistochemically assessed. Paired-t, ANOVA with Bonferroni, Kruskal–Wallis, and Bonferroni-corrected Mann–Whitney U tests were used for statistical analysis.
Results: GLUT5 mRNA expression and protein content did not differ between the groups. AQP7 mRNA levels significantly increased (4.8-fold) in group E compared with in group C (p<0.001). Compared with group C, no significant change was observed in AQP7 mRNA levels in groups HFD and HFD-E. The AQP7 staining score in group E was significantly higher than that in groups C (p<0.001), E (p<0.001), and HFD-E (p<0.001).
Conclusion: Our study indicates that exercise enhances cardiac AQP7 mRNA expression and protein content. However, HFD prevents the exercise-induced increase in cardiac AQP7 expression. This inhibitory effect may be related to the competition between fructose and glycerol as energy substrates in the rat heart subjected to 5 days of physical exercise. (Anatol J Cardiol 2016; 16: 916-22)

Keywords: high-fructose diet, exercise, glucose transporter 5, aquaporin 7, heart

Aziz Karaca, Orkide Palabıyık, Ebru Taştekin, Fatma Nesrin Turan, Selma Arzu Vardar. High fructose diet suppresses exercise-induced increase in AQP7 expression in the in vivo rat heart. Anatol J Cardiol. 2016; 16(12): 916-922

Corresponding Author: Selma Arzu Vardar, Türkiye