Age-Related Determinants of Stress-Induced Weight Change in Mice

25-day-old male mice showed a greater incidence of body weight loss and a late peak of plasma corticosterone elevation when exposed to tobacco smoke for 5 successive days, as compared with mice exposed to filtered smoke (gas phase) or air. 50-day-old mice had a greater incidence and magnitude of body weight loss and a late plasma corticosterone peak after 5 days of air exposure, but not with gas phase or nicotine + gas phase. Diencephalic serotonin, while higher among 25-day-old mice, did not differ as a function of the stress of confinement during exposure to the ventillatory stimulus or as a function of the different stimuli. The results suggest that weight loss and the time following stimulation at which plasma corticosterone is maximally elevated may serve as indices of stress and are consistent even when the stressor-susceptibility is age-related.