Figure 1.

Time course of aromatase inhibition and acute E₂ action on male sexual motivation. A, Blockade of local estrogen synthesis by the aromatase inhibitor VOR (50 μg) inhibits RCSM frequency within 30–240 min. B, Experimental design used to test the time course of acute E₂ action (50 μg) on behavior acutely inhibited by aromatase blockade. Black arrows indicate how long E₂ was injected before 15 min, 2 h, or 4 h testing conditions; the gray arrow indicates how long E₂ was injected before the 5 min test condition. C–F, The behavioral inhibition resulting from acute estrogen deprivation is prevented by E₂ (50 μg) injected 15 min (D) before the test, but not 5 (C), 120 (E), and 240 min (F) before the test. The Pre and Post black bars provide reference behavior frequencies after vehicle intracerebroventricular injections performed before and after the acute treatments, but these data are not included in the statistical analyses. Δp < 0.05, ΔΔp < 0.01, and ΔΔΔp < 0.001 versus vehicle (Veh) and ##p < 0.01 versus VOR 30 min by Newman–Keuls post hoc tests after identification of a significant overall treatment effect by two-way ANOVA (repeated measure; n = 13). H, The behavioral inhibition resulting from acute neuroestrogen depletion is prevented by E₂ injected 15 min but not after 2 or 4 h before. **p < 0.01 by Newman–Keuls post hoc tests following a significant treatment effect by one-way ANOVA (repeated measure; n = 12) on data expressed as percentage of VOR condition. G, Representation of individual values comparing the effect of E₂ after 15 min to the positive (Veh) and negative (VOR) controls .