Corticosteroids are stress-related hormones that maintain homeostasis. The most effective corticosteroids are corticosterone (CORT) in rodents and cortisol in primates. 11β-Hydroxysteroid dehydrogenase type 1 (11β-HSD1; EC 1.1.1.146), encoded by Hsd11b1, is a key regulator of the local concentration of CORT/cortisol. Hsd11b1 expression in layer 5 of the primary somatosensory cortex has been shown in adult mice. However, its localization in the entire neocortex, especially during development, has not been fully addressed. Here, we established robust and dynamic expression profiles of Hsd11b1 in the developing mouse neocortex. Hsd11b1 was found mostly in pyramidal neurons. By retrograde tracing, we observed that some Hsd11b1-positive cells were projection neurons, indicating that at least some were excitatory. At postnatal day 0 (P0), Hsd11b1 was expressed in the deep layer of the somatosensory cortex. Then, from P3 to P8, the expression area expanded broadly; it was observed in layers 4 and 5, spanning the whole neocortex, including the primary motor cortex (M1) and the primary visual cortex (V1). The positive region gradually narrowed from P14 onwards and was ultimately limited to layer 5 of the somatosensory cortex at P26 and later. Furthermore, we administered CORT to nursing dams to increase the systemic CORT level of their pups. Here, we observed a reduced number of Hsd11b1-positive cells in the neocortex of these pups. Our observation suggests that Hsd11b1 expression in the developing neocortex is affected by systemic CORT levels. It is possible that stress on mothers influences the neocortical development of their children.

中文翻译：

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Hsd11b1 表达区的瞬时扩展，编码 11β-羟基类固醇脱氢酶 1 型，在发育中的小鼠新皮质中

皮质类固醇是维持体内平衡的压力相关激素。最有效的皮质类固醇是啮齿动物中的皮质酮 (CORT) 和灵长类动物中的皮质醇。由Hsd11b1编码的 11β-羟基类固醇脱氢酶 1 型（11β-HSD1；EC 1.1.1.146）是局部 CORT/皮质醇浓度的关键调节剂。Hsd11b1在成年小鼠的初级体感皮层第 5 层表达。然而，它在整个新皮质中的定位，特别是在发育过程中，尚未得到充分解决。在这里，我们在发育中的小鼠新皮质中建立了Hsd11b1 的稳健和动态表达谱。Hsd11b1主要存在于锥体神经元中。通过逆行追踪，我们观察到一些Hsd11b1阳性细胞是投射神经元，表明至少有一些是兴奋性的。在出生后第 0 天 (P0)，Hsd11b1在体感皮层的深层表达。然后，从P3到P8，表达区域广泛扩大；它在第 4 层和第 5 层中观察到，跨越整个新皮层，包括初级运动皮层 (M1) 和初级视觉皮层 (V1)。阳性区域从 P14 开始逐渐变窄，最终限制在 P26 及以后的体感皮层的第 5 层。此外，我们对哺乳大坝进行了 CORT，以提高其幼崽的全身 CORT 水平。在这里，我们观察到这些幼崽的新皮质中Hsd11b1阳性细胞数量减少。我们的观察表明Hsd11b1发育中的新皮质中的表达受系统性 CORT 水平的影响。母亲的压力可能会影响孩子的新皮质发育。