Table 1.

Effects of treadmill running on hippocampal or plasma gonadal hormone levels

	Sham		ORX
	Sedentary	Exercise	Sedentary	Exercise
Hippocampus
DHT (nM)	2.30 ± 0.3	3.24 ± 0.2*	0.10 ± 0.01	0.22 ± 0.03*
DHT (ng/g wet weight)	0.67 ± 0.1	0.94 ± 0.1*	0.03 ± 0.002	0.06 ± 0.01*
Testosterone (nM)	20.5 ± 2.2	19.5 ± 1.6	0.77 ± 0.05	0.90 ± 0.07
Testosterone (ng/g wet weight)	5.9 ± 0.7	5.6 ± 0.5	0.22 ± 0.02	0.26 ± 0.02
Estradiol (nM)	0.68 ± 0.1	0.88 ± 0.1	0.46 ± 0.05	0.33 ± 0.08
Estradiol (ng/g wet weight)	0.19 ± 0.03	0.22 ± 0.04	1.29 ± 0.15	0.92 ± 0.24
Plasma
DHT (nM)	0.10 ± 0.04	0.10 ± 0.03	0.0014 ± 0.0005	0.0010 ± 0.0002
DHT (pg/mL)	29.62 ± 11.04	30.25 ± 8.32	0.40 ± 0.14	0.30 ± 0.05
Testosterone (nM)	5.11 ± 1.8	4.6 ± 1.2	0.00046 ± 0.0001	0.00069 ± 0.0002
Testosterone (pg/mL)	1472.5 ± 523.7	1326.3 ± 353.4	0.13 ± 0.03	0.20 ± 0.60

The steroid levels of Sham rats and ORX rats are shown. The steroids were separated into fractions of DHT, T, and E2 using a normal-phase HPLC system with a silica gel column, and then each steroid was measured using LC-MS/MS. After 2 wk of training, hippocampal DHT levels had increased in both Sham and ORX groups. There were no significant changes in hippocampal T and E2 levels or in plasma T and DHT levels. To compare the hippocampal level of steroids with plasma steroids, we converted to nanomolar concentration via the following estimation. First, 1 mL of plasma (93% is water) is assumed to have 1 g weight, as 1 mL of water is. Second, we assume that the hippocampal tissue having 1 g of wet weight has an approximate volume of 1 mL, as nearly 78% of the brain tissue consists of water (29). Data represent the mean ± SEM (n = 6–14 rats in each group).

*P < 0.05 in comparison with sedentary rats (two-way ANOVA). Sham: sham castrated; ORX: orchidectimized.