GABAergic neurons in hypothalamic paraventricular nucleus (PVN) play an important role in the central autonomic regulation of blood pressure (BP).Exercise has been shown to decrease the aging induced hypertension.This study investigated the effects of exercise on PVN GABAergic neurons.Two months Wistar rats were the young control group (YC) and 24 months Wistar rats were aging ones randomly divided into sedentary (SED), low frequency exercise (LEX, 12 m/min, 60 min/d, 3 d/week, 12 weeks) and high frequency exercise (HEX, 12 m/min,60 min/d, 5 d/week, 12 weeks).Heart rate (HR), BP and the autonomic nerve activity were measured and analyzed using a noninvasive tail-cuff system.The expression of glutamic acid decarboxylase (GAD) 67 was detected using immunofluorescence and Western blot.SED showed a higher rest HR, BP and higher sympathetic activity, while a lower parasympathetic activity with less PVN GABAergic neurons and PVN GAD67 expression compared to YC.Exercise has reversible beneficial effects on these parameters and these effects were more significant in HEX than in LEX.These data suggest GABAergic neurons activity in PVN is decline with the old, while regular exercise can improve the GABAergic autonomic regulation in olds.