Table 1.

Variation and heritability for neuroactive steroid levels across BXD strains.

	ID	N	pg/mL		95% CI	Fold- variation	F	p	η²	h²

			Mean ± SE	Range						Mean ± SE	Range
Pregnenolone
CTL M&F	17458	18	414 ± 20	272–578	372–457	2.1	(17,132)=1.72	0.049	0.20	0.20 ± 0.006	0.17–0.25
CIE M&F	17461	19	434 ± 34	304–919	362–507	3.0	(18,145)=2.15	0.007	0.23	0.23 ± 0.005	0.18–0.27
CTL M	17459	17	424 ± 31	288–737	358–490	2.6	(16,69)=1.70	0.076	0.34	0.34 ± 0.004	0.31–0.38
CTL F	17460	17	399 ± 24	261–648	348–451	2.5	(16,60)=1.75	0.071	0.39	0.39 ± 0.019	0.31–0.49
CIE M	17462	19	451 ± 45	279–1113	358–545	4.0	(18,78)=2.02	0.023	0.38	0.37 ± 0.017	0.26–0.43
CIE F	17463	16	394 ± 25	253–577	340–448	2.3	(15,64)=0.90	0.572	0.22	0.22 ± 0.009	0.20–0.31

3α,5α-THP
CTL M&F	17305	19	741 ± 40	375–1055	657–824	2.8	(18,143)=2.68	0.0007	0.28	0.28 ± 0.011	0.18–0.30
CIE M&F	17306	19	739 ± 36	460–1022	664–815	2.2	(18,157)=2.27	0.004	0.23	0.23 ± 0.005	0.18–0.25
CTL M	17448	18	683 ± 47	254–992	585–782	3.9	(17,78)=2.51	0.005	0.41	0.41 ± 0.030	0.24–0.44
CTL F	17449	17	818 ± 38	604–1360	737–900	2.3	(16,62)=0.91	0.559	0.24	0.24 ± 0.004	0.20–0.27
CIE M	17450	19	805 ± 62	385–1291	676–935	3.4	(18,87)=3.60	<0.0001	0.48	0.48 ± 0.011	0.42–0.52
CIE F	17451	16	696 ± 33	406–929	625–766	2.3	(15,67)=1.03	0.438	0.23	0.23 ± 0.008	0.16–0.26

3α,5α-THDOC
CTL M&F	17452	19	211 ± 21	94–448	168–254	4.8	(18,125)=2.57	0.001	0.30	0.30 ± 0.010	0.21–0.33
CIE M&F	17455	19	184 ± 14	93–333	155–214	3.6	(18,144)=1.39	0.146	0.17	0.17 ± 0.003	0.13–0.19
CTL M	17453	18	247 ± 25	118–498	187–292	4.2	(17,74)=2.45	0.006	0.42	0.42 ± 0.017	0.31–0.47
CTL F	17454	13	116 ± 19^a	30–243	75–157	8.2	(12,41)=2.80	0.012	0.54	0.54 ± 0.024	0.49–0.68
CIE M	17456	19	241 ± 23	93–512	193–290	5.5	(18,85)=2.48	0.004	0.40	0.40 ± 0.017	0.30–0.45
CIE F	17457	15	109 ± 18^a	41–292	70–148	7.1	(14,55)=2.64	0.008	0.47	0.48 ± 0.011	0.45–0.57

Male (M) and female (F) mice from each genotype received four cycles of chronic intermittent ethanol (CIE) vapor exposure (CIE group) or air exposure (CTL group) (16 h/day × 4 days, followed by 72-h withdrawal), alternated with 5-day drinking test cycles using a two-bottle (15% v/v ethanol vs. water) limited access (2 h/day) drinking model. Blood samples for neuroactive steroid assays were collected 72 h after a fifth CIE or air exposure cycle. Neuroactive steroid levels are expressed as pg/mL. Significant genetic variation was estimated by one-way ANOVA; putative differences in average neuroactive steroid levels were estimated by two-way ANOVA, with 2 treatment and sex as independent variables. Heritability (h²) was estimated as the ratio of the variance between strains divided by the sum of the within-strain and between-strain variances. The variance and standard error of the estimate of h² was computed using a jackknife procedure (Williams et al., 1996).

p < 0.001 vs. the respective male cases (two-way ANOVA, followed by Bonferroni post hoc test). ID refers to the GeneNetwork BXD phenotype ID for each trait.