Age-dependent changes in hormonal stress reactivity following repeated restraint stress throughout adolescence in male rats

Figures & data

Table 1. Mean (± SEM) body (g) and paired-testis (g) weights in 28d, 42d, 56d, and 70d male rats.

Days of age	Body weight (g)	Paired-testis weight (g)
28	100.2 ± 1.72^a	0.76 ± 0.02^a
42	234.9 ± 3.47^b	2.08 ± 0.03^b
56	346.6 ± 4.58^c	2.92 ± 0.04^c
70	443.0 ± 6.08^d	3.38 ± 0.04^d

Note that these data have been collapsed across stress condition and stress time point. For both body and parried-testis weight, values with different letters are significantly different from each other (all p < 0.001).

Figure 1. Mean (± SEM) plasma ACTH (pg/ml; A top row), corticosterone (ng/ml; B middle row), and corticosterone by log ACTH levels ([CORT]/log[ACTH]; C bottom rows) in 28d, 42d, 56d, and 70d male rats exposed to a single 30 min session of restraint stress (1RS; open circles) or a single 30 min session of restraint stress on four consecutive days (4RS, closed squares) before (0 min), immediately after termination of a 30 min session of restraint stress (30 min), or 40 min after termination of a 30 min session of restraint stress (70 min). Asterisks indicate that 4RS is significantly less than 1RS at that age and “#” indicates that 4RS is significantly greater than 1RS at that age. Note that for ease of visualization, significant main effects of age or stress condition are not indicated.

Figure 2. Mean (± SEM) plasma progesterone (ng/ml) in 28d, 42d, 56d, and 70d male rats exposed to a single 30 min session of restraint stress (1RS; open circles) or a single 30 min session of restraint stress on four consecutive days (4RS, closed squares) before (0 min), immediately after termination of a 30 min session of restraint stress (30 min), or 40 min after termination of a 30 min session of restraint stress (70 min). Asterisks indicate that 4RS is significantly less than 1RS at that age. Note that for ease of visualization, significant main effects of age or stress condition are not indicated.

Figure 3. Mean (± SEM) plasma testosterone (ng/ml) in 28d, 42d, 56d, and 70d male rats exposed to a single 30 min session of restraint stress (1RS; open circles) or a single 30 min session of restraint stress on four consecutive days (4RS, closed squares) before (0 min), immediately after termination of a 30 min session of restraint stress (30 min) or 40 min after termination of a 30 min session of restraint stress (70 min). Note that for ease of visualization, significant main effects of age or stress condition are not indicated.

Figure 4. Mean (± SEM) fecal boli per 30 min of the terminal stress session in 28d (closed circles), 42d (open circles), 56d (closed triangles), and 70d (open triangles) male rats exposed to a single 30 min session of restraint stress (1RS) or a single 30 min session of restraint stress on four consecutive days (4RS). Asterisks indicates a significant difference between the stress conditions.