Long-term effects of lifelong aerobic exercise on the stress response in middle-aged and old rats.

PIETRELLI A; DI NARDO, M; MASUCCI, A; BRUSCO, ALICIA; BASSO, N; MATKOVIC,L

Huerta Grande, Cordoba

Congreso; XXIX Annual Meeting and SAN-ISN Small Conference and Course; 2014

SAN

In order to understand the adaptive changes in adrenal glands, brain and behavior in response to lifelong endurance exercise, within the context of aging, we performed biochemicals, histopathological and behavioural studies in rats at middle (8 months) and old age (18 months). We designed an aerobic training programme with the treadmill running, considering that the adaptive response of the hypothalamo-pituitary-adrenal (HPA) axis differs between volitional and forced exercise. The levels of corticotrophin-releasing factor (CRF) in brain, hypothalamus and pituitary were affected by age and exercise, resulting significantly higher in old runners. Levels of brain corticosterone were found higher in younger runners and remarkably lower in old ones. Exercise did not change plasma or adrenal corticosterone levels in the absence of adrenocorticotropic hormone (ACTH). Aging produces a moderate increase of the noradrenaline without affecting the adrenergic response or the medular histoarchitecture. Old rats showed a significant decrease of the adrenal cortical activity accompanied by the reduction of fascicular and reticular cortical layers. Histological analysis revealed a significant increase in the adrenal cortex only in the young runners, caused by hypertrophy and/or hyperplasia of the fascicular and reticular layers. We conclude that chronic moderate exercise in the long-term can prevent or reduce some of the physiological and behavioral consequences of stressor exposure.