Figure 3. Microdialysis controls and basal neurosteroid E2 synthesis in the hippocampus.

(A) Probe recovery was similar (~30%) at both E2 concentrations tested and in both 1^st (closed circle) and 2^nd (open circle) 30 min samples, indicating a fast response in dialysate to changes in external E2 concentration (n=6 probes). (B) Dialysate and bath E2 concentrations were linearly correlated, with little difference between the 1^st (closed circles) and the 2^nd (open circles) 30 min samples at each concentration. (C) Carryover of E2 was evident in the 1^st (closed circle) but not in the 2^nd (open circle) 30 min samples after transferring a probe from an E2-containing to an E2-free bath. (D) E2 was detected in the hippocampus within 30 min of systemic E2 injection (10 μg in 25% ethanol/saline, s.c., n=2), followed by a gradual decline over 2 hr. (E) Retrodialysis of androstenedione (4-dione, 1 ng/ml, blue box), increased hippocampal E2 concentration by +8.9 ± 3.2 pg/ml (310 ± 67%, n=10, *p<0.05 relative to baseline (BL), paired t-tests).

DOI: http://dx.doi.org/10.7554/eLife.12917.007

Figure 3—figure supplement 1. Synthetic pathway for C19 and C18 steroids and the results of cross-reactivity/interference testing for EIA.

(A) Synthetic pathway for C19 and C18 steroids. The gray boxes indicate steroids that we tested for cross-reactivity/interference, and blue steroids are those tested by the manufacturer. Estradiol is shown in red. (B) Table listing results of all our cross-reactivity/interference tests for glucocorticoids, androgens, estrogens and other neuroactive steroids. These results showed that the EIA used has little to no cross-reactivity with non-estrogens.

DOI: http://dx.doi.org/10.7554/eLife.12917.008