Tanida Takashi, Yokoyama Toshifumi, Nakajima Takayuki, Kawai Honoka, Hoshi Nobuhiko, Kawata Mitsuhiro, Matsuda Ken Ichi
Department of Veterinary Anatomy, Graduate School of Veterinary Science, Osaka Metropolitan University, 1-58 Rinku-Orai Kita, Izumisano, Osaka 598-8531, Japan.
Department of Anatomy and Neurobiology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kawaramachi Hirokoji, Kamigyo-ku, Kyoto 602-8566, Japan.
Acta Histochem Cytochem. 2025 Aug 28;58(4):153-160. doi: 10.1267/ahc.25-00020. Epub 2025 Jul 24.
Sex-determining region Y () triggers testis development in mammals, and the presence or absence of testicular secretion determines their sex-specific brain phenotype. Mice with Y chromosome replaced by that of (Y ) frequently display sex reversal due to delayed expression. However, brain sexual dimorphism under conditions of disorders of sex development remains unclear. Here, we report sex differences in the sexually dimorphic nucleus of the preoptic area, delineated by cells positive for calbindin D28k, a male-predominant neuronal marker (CALB-SDN), in Y mice. The mice were divided into females and males according to gonadal phenotype. Cells immunoreactive (ir) for calbindin D28k (CALB) were more extensively distributed in male Y mice, compared with females. The CALB-ir cell numbers in the CALB-SDN were significantly higher in Y males than in Y females, which had numbers comparable to wild type females. No left-right differences in CALB-ir cell numbers were observed in the CALB-SDN. Collectively, these results demonstrate that sexual dimorphism of the CALB-ir cell cluster in the CALB-SDN strongly correlates with the gonadal sex phenotype rather than with the chromosomal sex in the Y mice, suggesting the effect of testicular secretion on the brain sexual differentiation with aberrant Y-linked gene expression.
Y染色体性别决定区（SRY）触发哺乳动物睾丸发育，睾丸分泌的有无决定其性别特异性脑表型。Y染色体被雌性小鼠的Y染色体取代（SxrY）的小鼠由于SRY表达延迟经常出现性反转。然而，性发育障碍条件下脑性二态性仍不清楚。在此，我们报告了在SxrY小鼠中，由钙结合蛋白D28k（一种雄性占主导的神经元标记物，CALB-SDN）阳性细胞描绘的视前区性二态核中的性别差异。根据性腺表型将小鼠分为雌性和雄性。与雌性相比，钙结合蛋白D28k（CALB）免疫反应性（ir）细胞在雄性SxrY小鼠中分布更广泛。SxrY雄性小鼠CALB-SDN中CALB-ir细胞数量显著高于SxrY雌性小鼠，后者的数量与野生型雌性相当。在CALB-SDN中未观察到CALB-ir细胞数量的左右差异。总体而言，这些结果表明，SxrY小鼠中CALB-SDN中CALB-ir细胞簇的性二态性与性腺性别表型密切相关，而非与染色体性别相关，提示睾丸分泌对伴有异常Y连锁基因表达的脑性分化的影响。
