Aerobic Training (T) Improves the Integrity Blood Brain Barrier (BBB) in Spontaneously Hypertensive Rats (SHR)

It is well known that hypertensive rats exhibited a deficient BBB. To evaluate the combined effect of hypertension and T on BBB integrity within autonomic areas, SHR were submitted to treadmill T (55% of maximum capacity, 1h/day, 5 d/week) or kept sedentary (S) for 2 month. After hemodynamic measurements at rest, rats were anesthetized for carotid infusion with dextrans FITC‐10 kDA + RHO‐70 kDA (286μl/100g). Twenty minutes later, brains were removed, post‐fixed and cryoprotected; sequential slices (30 μm) of the hypothalamic paraventricular nucleus (PVN) were acquired in a fluorescent microscope and processed by Image J analysis. BBB integrity was assessed by degree of FITC leakage into the extravascular CNS space. Eight‐weeks of T caused a significant MAP and HR reduction (155±6 mmHg, 357±7 b/min vs. 164±8 mmHg, 397±13 b/min before T). Hemodynamic changes were accompanied by a marked reduction on dye leakage area within the ventromedial and posterior PVN (on average from 16±0.5% to 7±1.5% after T, corresponding to a reduction of 56%). Data showed a novel beneficial effect of training to reduce BBB leakage in hypertensive rats. This adaptive response may contribute to the improvement of brain perfusion after training. Financial Support: FAPESP