Effects of Voluntary Running Wheel Activity and Hypertension on the Brain of Female Spontaneously Hypertensive Rats (SHRs)

Low physical activity is a common risk factor for hypertension and dementia. We investigated whether voluntary running wheel activity (VRWA) ameliorates the effects of hypertension in the brain. Forty-six six-week-old female spontaneously hypertensive rats were randomly selected in a sedentary control group (SHR-S; n = 21) or had access to running wheels during their active nighttime (SHR-R; n = 15). Age-matched normotensive Wistar rats served as controls (WIS; n = 10). Animals were sacrificed after six months. The cortex, medulla oblongata, and olfactory bulb were prepared. Oxidative stress was analyzed by DHE staining, protein expression by Western blots, mRNA expression by qRT-PCR and blood pressure by a tail-cuff method. VRWA reduced heart rates but not blood pressure. All SHRs displayed a strong reduction of Ucp2 brain expression in a blood-pressure-dependent way. VRWA did not improve the expression of Ucp2 but increased the expression of Cat and reduced oxidative stress in the cortex. Hypertension increased the expression of Ren in the medulla oblongata without any effect of VRWA on this parameter. VRWA generally affected mRNA expression stronger in the cortex than in the other parts of the brain. In conclusion, high physical activity ameliorated oxidative stress in the cortex in a blood-pressure-independent way.