Wood Elizabeth K, Jarman Parker, Cash Elysha, Baxter Alexander, Capitanio John P, Higley J Dee
Department of Psychology, Brigham Young University, Provo, UT, United States.
Department of Psychology, University of California, Davis, Davis, CA, United States.
Front Behav Neurosci. 2020 Sep 3;14:94. doi: 10.3389/fnbeh.2020.00094. eCollection 2020.
The second-to-fourth digit ratio (2D:4D ratio) is considered a postnatal proxy measure for the degree of prenatal androgen exposure (PAE), which is the primary factor responsible for masculinizing the brain of a developing fetus. Some studies suggest that the organizational effects of PAE may extend to the hypothalamic-pituitary-adrenal (HPA) axis response to stress. This study investigates the relationship between 2D:4D ratio and HPA axis functioning using a rhesus monkey () model. Subjects were = 268 (180 females, 88 males) rhesus monkey infants (3-4 months of age). Plasma cortisol concentrations were assayed from two blood samples obtained during a 25-h experimental social separation stressor at 2- and 7-h post-separation. Subjects' 2D:4D ratio was measured later in life ( = 6.70 years). It was hypothesized that infant rhesus monkeys that exhibited a more masculine-like 2D:4D ratio would show lower levels of circulating cortisol after a social separation and relocation stressor. The results showed that there was a sex difference in the left-hand 2D:4D ratio. The results also showed that there was an overall sex difference in cortisol concentrations and that female, but not male, monkeys that exhibited a more masculine-like right- and left-hand 2D:4D ratio exhibited lower mean stress-induced cortisol concentrations early in life. These findings suggest that higher levels of prenatal androgens in females, as measured by 2D:4D ratio, may be related to an attenuated HPA axis stress-response, as measured by plasma cortisol levels. To the extent that these findings generalize to humans, they suggest that the organizational effects of PAE extend to the infant HPA axis, modulating the HPA axis response, particularly in females.
食指与无名指长度比（2D:4D 比）被认为是产前雄激素暴露（PAE）程度的一种产后替代指标，而产前雄激素暴露是导致发育中胎儿大脑男性化的主要因素。一些研究表明，PAE 的组织效应可能会延伸至下丘脑 - 垂体 - 肾上腺（HPA）轴对应激的反应。本研究使用恒河猴模型调查 2D:4D 比与 HPA 轴功能之间的关系。研究对象为 268 只（180 只雌性，88 只雄性）恒河猴幼崽（3 - 4 个月大）。在 25 小时的实验性社会隔离应激期间，于隔离后 2 小时和 7 小时采集两份血样，测定血浆皮质醇浓度。研究对象的 2D:4D 比在其日后生活中（平均年龄 = 6.70 岁）进行测量。研究假设为，2D:4D 比更具男性化特征的恒河猴幼崽在经历社会隔离和重新安置应激后，其循环皮质醇水平会更低。结果显示，左手的 2D:4D 比存在性别差异。结果还表明，皮质醇浓度总体上存在性别差异，并且 2D:4D 比更具男性化特征的雌性猴子（而非雄性猴子）在生命早期应激诱导的平均皮质醇浓度较低。这些发现表明，以 2D:4D 比衡量的女性较高水平的产前雄激素，可能与以血浆皮质醇水平衡量的 HPA 轴应激反应减弱有关。就这些发现推广至人类的程度而言，它们表明 PAE 的组织效应会延伸至婴儿 HPA 轴，调节 HPA 轴反应，尤其是在女性中。
