Behrouz Baghaiee - Department of Physical Education and Sport Science, Jolfa Branch, Islamic Azad University, Jolfa, Iran
Pouran Karimi - Department of Physical Education and Sport Science, Jolfa Branch, Islamic Azad University, Jolfa, Iran
Marefat Siahkouhian - Department of Physical Education and Sport Science, University of Mohaghegh Ardabili, Ardabil, Iran
Linda S Pescatello - Department of Kinesiology, College of Agriculture, Health and Natural Resources, University of Connecticut, Connecticut, USA

Objective(s): This study aimed to investigate the effect of aerobic training on serum levels of Klotho, cardiac tissue levels of H۲O۲ and phosphorylation of ERK۱/۲ and P۳۸ as well as left ventricular internal diameter (LVID), the left ventricle wall thickness (LVWT) and fibrosis in middle-aged rats. Materials and Methods: Forty wistar rats, including young rats (n=۱۰, ۴ month-old) and middle-aged rats (n=۳۰, ۱۳-۱۵ months-old) were enrolled in this experimental study. The all young and ۱۰ middle-aged rats were sacrificed (randomly) under deep anesthesia without any exercise training as normal young control and normal middle-aged control respectively. The remaining ۲۰ middle-aged rats participated in ۴ (n=۱۰) or ۸-week (n=۱۰) aerobic exercise training. Results: There were significant differences in the plasmatic Klotho levels and the heart tissue levels of phosphorylated-ERK۱/۲ (p-ERK۱/۲), P-P۳۸ and H۲O۲, LVWT, LVID and fibrosis between young and middle-aged rats (P=۰.۰۱). Plasmatic Klotho level was significantly increased after eight weeks training (P=۰.۰۱۱). Also, p-ERK۱/۲ was significantly decreased after eight weeks and p-P۳۸ was significantly decreased in the fourth (P=۰.۰۱) and eight weeks of training (P=۰.۰۱). A similar decrease was reported for aging-induced H۲O۲ in the fourth (P=۰.۰۱۶) and eighth weeks (P=۰.۰۰۱). LVID was significantly increased in eight weeks, but LVWT and fibrosis was significantly reduced in the eighth week (P=۰.۰۱۱, P=۰.۰۲۸, P=۰.۰۰۱ respectively).Conclusion: Moderate aerobic training attenuates aging-induced pathological cardiac hypertrophy at least partially by restoring the Klotho levels, attenuating oxidative stress, and reduction in the phosphorylation of ERK۱/۲, P۳۸ and fibrosis.

Exercise, Fibrosis, H۲O۲, Left ventricular hypertrophy, Klotho, Mitogen-activated protein, kinase