Table 1.

Mass spectrometric analysis of the concentration of steroids in the hippocampus and plasma of adult female rats.

	Proestrus	Estrus	Diestrus 1	Diestrus 2	OVX
(A) Hippocampus
PROG (nM)a	55.7 ± 6.8b (nc = 4)	40.7 ± 7.8 (n = 4)	87.0 ± 8.1 (n = 3)	48.0 ± 6.2 (n = 4)	24.5 ± 3.3 (n = 5)
PROG (ng/g wet weight)	17.5 ± 2.1	12.8 ± 2.5	27.4 ± 2.5	15.1 ± 1.9	7.7 ± 1.0
El (nM)	0.36 ± 0.07 (n = 4)	0.045 ± 0.004 (n = 4)	0.05 ± 0.0l (n = 4)	0.10 ± 0.01 (n = 4)	0.025 ± 0.003 (n = 3)
El (ng/g wet weight)	0.097 ± 0.019	0.012 ± 0.001	0.014 ± 0.003	0.027 ± 0.003	0.007 ± 0.001
17ß-E2 (nM)	4.3 ± 1.0 (n = 6)	1.0 ± 0.4 (n = 4)	0.51 ± 0.05 (n = 3)	0.7 ± 0.1 (n = 4)	0.7 ± 0.1 (n = 4)
17ß-E2 (ng/g wet weight)	1.18 ± 0.27	0.27 ± 0.11	0.14 ± 0.01	0.33 ± 0.03	0.33 ± 0.03
ADione (nM)	1.6 ± 0.1 (n = 4)	0.7 ± 0.1 (n = 4)	1.1 ± 0.4 (n = 4)	0.83 ± 0.08 (n = 4)
ADione (ng/g wet weight)	0.46 ± 0.03	0.20 ± 0.03	0.32 ± 0.11	0.24 ± 0.02
T (nM)	1.6 ± 0.5 (n = 4)	2.3 ± 1.1 (n = 4)	1.3 ± 0.6 (n = 3)	1.2 ± 0.7 (n = 4)
T (ng/g wet weight	0.46 ± 0.14	0.66 ± 0.32	0.37 ± 0.17	0.35 ± 0.20
(B) Plasma
PROG (nM)	20.5 ± 2.6 (n = 4)	16.7 ± 2.3 (n = 4)	51.6 ± 17.9 (n = 3)	24.1 ± 7.3 (n = 4)	10.1 ± 1.6 (n = 5)
PROG (ng/g wet weight)	4.4 ± 0.8	5.3 ± 0.7	16.2 ± 5.6	7.6 ± 2.3	3.2 ± 0.5
E1 (nM)	0.082 ± 0.006 (n = 4)	0.004 ± 0.001 (n = 4)	0.009 ± 0.001 (n = 4)	0.031 ± 0.002 (n = 4)	0.002 ± 0.001 (n = 4)
E1 (ng/g wet weight)	0.022 ± 0.002	0.001 ± 0.000	0.002 ± 0.000	0.008 ± 0.001	0.001 ± 0.000
17ß-E2 (nM)	0.111 ± 0.008 (n = 6)	0.017 ± 0.005 (n = 6)	0.009 ± 0.001 (n = 5)	0.029 ± 0.005 (n = 6)	0.005 ± 0.000 (n = 5)
17ß-E2 (ng/g wet weight)	0.030 ± 0.002	0.005 ± 0.001	0.002 ± 0.000	0.008 ± 0.001	0.001 ± 0.000
ADione (nM)	1.0 ± 0.2 (n = 4)	0.06 ± 0.01 (n = 4)	0.119 ± 0.005 (n = 4)	0.33 ± 0.07 (n = 4)
ADione (ng/g wet weight)	0.29 ± 0.06	0.017 ± 0.003	0.034 ± 0.001	0.06 ± 0.02
T (nM)	0.10 ± 0.03 (n = 4)	0.013 ± 0.004 (n = 4)	0.020 ± 0.007 (n = 3)	0.06 ± 0.02 (n = 4)
T (ng/g wet weight)	0.029 ± 0.009	0.004 ± 0.001	0.006 ± 0.002	0.017 ± 0.006
(C) OVX ± E2d
		Hippocampus		Plasma
17ß-E2 (nM)		3.8 ± 0.4 (n = 3)		1.3 ± 0.4 (n = 4)
17ß-E2 (ng/g wet weight)		1.0 ± 0.1		0.36 ± 0.10

^aConcentration in nM is calculated using the average volume of 0.124 mL for one whole hippocampus that has 0.124 ± 0.002 g wet weight (n = 44). We assumed that tissue having 1 g of wet weight has an approximate volume of 1 ml, since the major part of tissue consists of water whose 1 mL weight is 1 g. The volume should be decreased by less than 10%, due to the specific volumes of proteins and lipids (0.7–0.8 ml/g) (see McIlwain, 1985). Intact shows the averaged values from intact and sham-operated rats, because there were no significant differences between these two groups of rats.

^bData are expressed as mean ± sem.

^cNumber of animals (i.e., the number of hippocampi).

^dE2 (40 μg/kg body weight) was s.c. injected 5 h before measurements.