Effect of the aerobic exercise and the environmental enrichment on the reduction of the anxiety levels in the aging

Abstract

The environmental enrichment (EE) and the aerobic exercise (EX) are interventions capable of reducing anxiety levels in the aging, but few is known about how they modulating the projections to the hypothalamic-pituitary axis (HPA). We studied the effect of an EE and EX programs carried out during two months in 18 month-old Wistar rats assigned to 3 groups: (CO, N=6), EE (N=8) y EX (N=8). The EX program was carried out during 15min/day and the EE group was housed in a big cage with different objects frequently changed. Through the cytochrome c oxidase histochemistry (COx), we analysed the metabolic activity of several brain regions involved in the anxiety response. The EE reduced the brain activity of regions involved in the activation of the HPA axis (infralimbic cortex, basolateral amygdala and the hypothalamic paraventricular nucleus (p<0.05). On the other hand, the EX program increased the activity of brain regions involved in the inhibition of the HPA axis (cingulate cortex, bed nucleus of the stria terminalis and the dorsal hippocampus (p<0.05). In conclusion, it seemed that the EE and the EX modulate in different way the activity of brain regions that project to the HPA axis and they could constitute successful interventions to reduce the anxiety levels in the aging.