title: High fructose diet suppresses exercise-induced increase in AQP7 expression in the in vivo rat heart.
abstract: 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.
  
  
  
  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.
  
  
  
  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).
  
  
  
  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.
authors.affiliation: Department of Physiology, Faculty of Medicine, Trakya University, Edirne-Turkey.
authors.forename: Aziz
authors.initials: A
authors.lastname: Karaca
authors.affiliation: Department of Biophysics, Faculty of Medicine, Trakya University, Edirne-Turkey.
authors.forename: Orkide
authors.initials: O
authors.lastname: Palabıyık
authors.affiliation: Department of Pathology, Faculty of Medicine, Trakya University, Edirne-Turkey.
authors.forename: Ebru
authors.initials: E
authors.lastname: Taştekin
authors.affiliation: Department of Biostatistics, Faculty of Medicine, Trakya University, Edirne-Turkey.
authors.forename: Fatma Nesrin
authors.initials: FN
authors.lastname: Turan
authors.affiliation: Department of Physiology, Faculty of Medicine, Trakya University, Edirne-Turkey. arzuvardar22@hotmail.com.
authors.forename: Selma Arzu
authors.initials: SA
authors.lastname: Vardar
mesh_terms: D000818:Animals; D020346:Aquaporins / Q000378:metabolism*; D004032:Diet; D000073417:Dietary Sugars / Q000378:metabolism*; D005632:Fructose / Q000378:metabolism*; D005990:Glycerol; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C491926:Aqp7 protein, rat; D020346:Aquaporins; D000073417:Dietary Sugars; D012333:RNA, Messenger; D005632:Fructose; D005990:Glycerol