Table 3.

Stimulus-specific increases of plasma corticosterone levels

	Treatment paradigm
	Lab controls	Hyperthermia	Cold challenge	Stress-free
Plasma corticosterone	2.17 ± 0.56	4.42 ± 1.13	6.58* ± 0.72	0.70 ± 0.08

Plasma corticosterone levels (expressed in μg/dl), a measure of the neuroendocrine stress response, were influenced by the cold challenge but not by hyperthermia. Stress-free controls were killed within 45 s of entry into the animal facility; laboratory controls were also separated from their mothers for the duration of the experimental manipulations. They were killed with the other groups, that were subjected to 30 min of hyperthermia or to cold. ANOVA showed a robust effect of treatment: P < 0.0001, sum of squares 118 (residual 35).

^*Significantly different from laboratory controls (P < 0.01, Bonferroni’s post hoc test).