Department of Physiology, Nippon Medical School, 1-1-5, Sendagi, Bunkyo-ku, Tokyo 113-8602, Japan.
Endocrinology. 2010 Apr;151(4):1923-8. doi: 10.1210/en.2009-1022. Epub 2010 Feb 25.
The volume of the sexually dimorphic nucleus of the preoptic area (SDN-POA) is two to four times larger in male rats than in females; however, the mechanism for the establishment of sexual dimorphism and the function of this nucleus is almost unknown. Perinatal estrogen can cause sexual dimorphism via the estrogen receptor alpha (ERalpha). Recently, transgenic rats were generated that express enhanced green fluorescent protein (EGFP) under the control of the ERalpha gene promoter 0/B to tag ERalpha-positive neurons in the brain. In the present study, we examined whether this EGFP expression could be a marker for the SDN-POA in adults. EGFP-labeled cells were distributed in the core of the SDN-POA (0/B-SDN) of male and female transgenic rats, in accordance with the Nissl staining and immunoreactivity for the SDN marker, calbindin. They were also immunoreactive for ERalpha. The core was bigger in volume and contained more 0/B-SDN neurons in males than in females. The EGFP-tagged cells were packed more densely in the female core than that in males. Subcutaneous injection of 100 mug 17beta-estradiol to females on the day of birth, or orchidectomy of male neonates, reversed the sexually dimorphic phenotype of the volume of the 0/B-SDN, despite not affecting the cell number. We suggest that this EGFP expression in the SDN-POA could be a useful marker to clarify the sexual differentiation and function of the SDN-POA. Moreover, the ERalpha gene promoter 0/B plays a key role in the organization of the sexual differentiation of the SDN-POA.
性二型核的视前区（SDN-POA）的体积是雄性大鼠比雌性大鼠大两到四倍; 然而，建立性二型的机制和这个核的功能几乎是未知的。围产期雌激素可以通过雌激素受体 alpha (ERalpha) 引起性二型。最近，生成了表达增强型绿色荧光蛋白（EGFP）的转基因大鼠，该蛋白受 ERalpha 基因启动子 0/B 的控制，以标记大脑中的 ERalpha 阳性神经元。在本研究中，我们检查了这种 EGFP 表达是否可以作为成年 SDN-POA 的标志物。EGFP 标记的细胞分布在雄性和雌性转基因大鼠 SDN-POA 的核心（0/B-SDN）中，与 Nissl 染色和 SDN 标志物 calbindin 的免疫反应性一致。它们也对 ERalpha 有免疫反应性。核心的体积更大，雄性中的 0/B-SDN 神经元数量多于雌性。雌性核心中的 EGFP 标记细胞比雄性更密集地包装。出生当天给雌性皮下注射 100 微克 17β-雌二醇，或对雄性新生儿进行睾丸切除术，尽管不影响细胞数量，但可以逆转 0/B-SDN 体积的性二型表型。我们认为，SDN-POA 中的这种 EGFP 表达可能是阐明 SDN-POA 的性分化和功能的有用标志物。此外，ERalpha 基因启动子 0/B 在 SDN-POA 的性分化组织中起着关键作用。
