Fig. 2.

Exogenous estradiol inhibits Purkinje cell dendritic development and endogenous estradiol is necessary for normal development. A, PGE2 treatment significantly reduces the length of Purkinje dendrites regardless of sex (*, P < 0.05, two-way ANOVA). B, PGE2 treatment also significantly reduced the total number of dendritic spines per Purkinje neuron when counted at ×100 magnification (*, P < 0.05, two-way ANOVA). C, Estradiol treatment significantly reduced the length of Purkinje dendrites, regardless of whether it was combined with the COX inhibitor, nimesulide (two-way ANOVA, a priori comparisons with Bonferroni-Sidak correction: a, P < 0.01 compared to vehicle; b, P < 0.01 compared to nimesulide). D, In the same animals, estradiol also decreased the number of spines per Purkinje neuron regardless of nimesulide coadministration (two-way ANOVA, a priori comparisons with Bonferroni-Sidak corrections; a, P < 0.01 compared to vehicle; b, P < 0.01 compared to nimesulide) when counted at ×60 magnification. The lack of effect of a COX inhibitor on estradiol action indicates that prostaglandin synthesis is not necessary for estradiol-induced reductions in Purkinje cell dendritic arbor size and suggests PGE2 synthesis is upstream of estradiol signaling. E, Sholl analysis characterizing the number of intersection of dendrites with 10 μm spaced concentric circles relative to their distance from the soma. Estradiol administration or coadministration of estradiol and nimesulide reduced the number of intersections as a function of their distance, such that the dendritic tree is restricted to a smaller area and branches less frequently (Friedman Test, post hoc: a priori Wilcoxon-Signed Rank Tests: a, P < 0.01 compared to vehicle; b, P < 0.01 compared to nimesulide). F, The cumulative frequency of intersections of dendrite segments with concentric shifts to the left in estradiol treated animals regardless of nimesulide treatment, better depicting that the neuron's dendritic arbor is restricted to a smaller area (Friedman Test; post hoc: a priori Wilcoxon-Signed Rank Tests: a, P < 0.001 compared to vehicle; b, P < 0.001 compared to nimesulide). G, Images of typical Golgi-Cox impregnated Purkinje cells from the same treatment groups representing the group means. Scale bar, 25 microns. Data are presented as means ± sems after collapsing across sex following a two-way ANOVA for treatment and sex. No significant effects of sex or interactions between sex and treatment were found. E₂, Estradiol.