Table 1.

Bodyweight, tibial length, trabecular and cortical bone parameters measured using high-resolution μCT and serum analyses.

Sex	Male		Female
Housing	Group	Individual	Group	Individual
Bodyweight (g)	30.1 ± 0.7	28.9 ± 0.7	22.0 ± 0.7	21.8 ± 0.4
Fighting (no./h)	1.3 ± 0.5	N/A	0 ± 0	N/A
Tibial length (mm)	18.3 ± 0.1	18.1 ± 0.2	17.7 ± 0.1	17.7 ± 0.1
Trabecular bone
BV/TV (%)
Left control	14.6 ± 0.5	11.4 ± 0.3c	6.8 ± 0.2	6.9 ± 0.9
Right loaded	14.7 ± 0.6	14.6 ± 0.5f	10.2 ± 0.5e	9.8 ± 1.1e
Tb.Th (mm)
Left control	0.045 ± 0.002	0.038 ± 0.001b	0.047 ± 0.002	0.044 ± 0.003
Right loaded	0.047 ± 0.001d	0.046 ± 0.002f	0.058 ± 0.002e	0.056 ± 0.001d
Tb.Sp (mm)
Left control	0.172 ± 0.001	0.170 ± 0.002	0.256 ± 0.009	0.241 ± 0.017
Right loaded	0.169 ± 0.002	0.166 ± 0.002	0.242 ± 0.008d	0.240 ± 0.012
Tb.N (mm− 1)
Left control	3.25 ± 0.06	3.01 ± 0.06a	1.44 ± 0.06	1.60 ± 0.29
Right loaded	3.11 ± 0.10	3.18 ± 0.02d	1.77 ± 0.12d	1.74 ± 0.22
Cortical bone
Ct.Ar (mm2)
Left control	0.85 ± 0.01	0.76 ± 0.02b	0.68 ± 0.02	0.66 ± 0.02
Right loaded	0.89 ± 0.01d	0.83 ± 0.02f	0.79 ± 0.02f	0.74 ± 0.002d
Tt.Ar (mm2)
Left control	1.52 ± 0.03	1.35 ± 0.04a	1.17 ± 0.04	1.15 ± 0.03
Right loaded	1.55 ± 0.04	1.43 ± 0.03e	1.26 ± 0.03e	1.22 ± 0.02d
Ma.Ar (mm2)
Left control	0.67 ± 0.03	0.59 ± 0.03	0.49 ± 0.02	0.50 ± 0.01
Right loaded	0.65 ± 0.03	0.60 ± 0.02	0.47 ± 0.01	0.48 ± 0.02
Ct.Ar/Tt.Ar (%)
Left control	55.8 ± 0.8	56.3 ± 0.7	58.1 ± 0.4	57.0 ± 0.9
Right loaded	57.8 ± 1.0	58.0 ± 1.0e	62.6 ± 0.6e	60.9 ± 0.8d
Ct.Th (mm)
Left control	0.147 ± 0.002	0.142 ± 0.002	0.143 ± 0.003	0.140 ± 0.004
Right loaded	0.160 ± 0.003e	0.153 ± 0.002e	0.160 ± 0.004f	0.159 ± 0.003d
J (mm4)
Left control	0.439 ± 0.015	0.365 ± 0.015b	0.267 ± 0.017	0.254 ± 0.011
Right loaded	0.452 ± 0.016	0.398 ± 0.018e	0.321 ± 0.015e	0.296 ± 0.007d
Serum
Testosterone (ng/ml)	4.29 ± 6.28	3.81 ± 3.31	–	–
Corticosterone (ng/ml)	89.1 ± 15.6	187.2 ± 37.4a	298.5 ± 74.0	265.9 ± 42.5

Data represented as mean ± SEM (male and grouped female n = 6; individual female n = 4). BV/TV = bone volume fraction; Tb.Th = trabecular thickness; Tb.Sp = trabecular separation; Tb.N = trabecular number; Ct.Ar = cortical bone area; Tt.Ar = total cross-sectional area inside the periosteal envelope; Ma.Ar = medullary area; Ct.Ar/Tt.Ar = cortical area fraction; Ct.Th = cortical thickness; J = polar moment of inertia. ^ap < 0.05, ^bp < 0.01, ^cp < 0.001 individual compared to group housed mice of the same sex; ^dp < 0.05, ^ep < 0.01, ^fp < 0.001 comparing left control with right loaded limbs.