Effect of aging on 24-hour pattern of stress hormones and leptin in rats

CANO P; CARDINALI DP; SPINEDI E; ESQUIFINO AI

LIFE SCIENCES

Elsevier

Lugar: New York; Año: 2008 vol. 83 p. 142 - 148

0024-3205

This work analyzes the 24-h changes of hypothalamic-pituitary-adrenal (HPA) axis activity and leptin release in aged rats. Three- and 22-months old male Wistar rats were killed at 6 time intervals during a 24-h cycle (n= 8-10 rats/group). Aging augmented plasma ACTH while decreased plasma and adrenal gland corticosterone levels. Plasma and adrenal corticosterone peaked in young rats at the second half of the scotophase, concomitantly with the maxima in ACTH levels. In aged rats plasma corticosterone peaked at the early scotophase while plasma ACTH and adrenal corticosterone levels did not show any significant 24 h variations. Aging augmented circulating leptin, with a significant interaction "age x time" in the factorial ANOVA, i.e. only in young rats time of day changes were significant, with lowest values of leptin at the middle of the light period and higher values at night. When plasma leptin was expressed on body weight basis, the age-related differences became not significant but the daily pattern of plasma leptin found in young rats persisted. Plasma and adrenal corticosterone levels correlated significantly with plasma ACTH only in young rats. Likewise, plasma leptin correlated with plasma corticosterone only in young rats. These changes can be attributed to a disrupting effect of aging on the homeostatic mechanisms modulating HPA activity and leptin release.