Estrogen-induced signaling mechanisms involed in the establishment of the sexual dimorphysm of the rat brain

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In the rat brain, the sexually dimorphic nucleus (SDN) of the medial preoptic area (POA) is a major site for controlling sexual dimorphic behavior and physiological functions. The dimorphism is formed by the exposure to 17beta;-estradiol (E2) during the critical period, which begins around embryonic day 18. In order to explore key factors and mechanisms involved in the establishment of sex differences in response to E2, we prepared total RNA from brain slices containing SDN from female rats treated with E2 at birth, which was subjected to DNA microarray. The expression of the gene for protein kinase C-delta; (PKC-delta;) was significantly up-regulated by E2. We then examined the downstream effectors of PKC-delta; by Western blotting and immunohistochemistry, and found the involvement of the PKC-delta;/Rac1/LIMK1/cofilin pathway. This work demonstrated that cell migration enhanced by actin dynamics is a cue to create the sexual dimorphism in POA of the rat brain.