Table 2.

Serum corticosterone concentrations in control and stressed animals

	Control	Acute	Chronic	Combined
Stress
Number of animals	n=15	n=15	n=15	n=15
Corticosterone (ng/ml)	137±10	627±26*,‡	65±7†	601±20*,‡

Serum corticosterone (CORT) is represented as mean±s.e.m. (n=15). Statistical analysis by one-way ANOVA followed by Tukey's post hoc test indicated a significant increase in CORT concentration caused by acute immobilization stress (*P<0·001 versus control) or combined stress (chronic isolation plus acute immobilization stress *P<0·001 versus control). The chronically isolated animals had significantly decreased CORT concentrations in respect to control level (^†P<0·01), acute (^‡P<0·001) or combined stress animals (^‡P<0·001).