Chronic stress suppresses the expression of cutaneous hypothalamic-pituitary-adrenocortical axis elements and melanogenesis.

Chronic stress can affect skin function, and some skin diseases might be triggered or aggravated by stress. Stress can activate the central hypothalamic-pituitary-adrenocortical (HPA) axis, which causes glucocorticoid levels to increase. The skin has HPA axis elements that react to environmental stressors to regulate skin functions, such as melanogenesis. This study explores the mechanism whereby chronic stress affects skin pigmentation, focusing on the HPA axis, and investigates the role of glucocorticoids in this pathway. We exposed C57BL/6 male mice to two types of chronic stress, chronic restraint stress (CRS) and chronic unpredictable mild stress (CUMS). Mice subjected to either stress condition showed reduced melanogenesis. Interestingly, CRS and CUMS triggered reductions in the mRNA expression levels of key factors involved in the HPA axis in the skin. In mice administered corticosterone, decreased melanin synthesis and reduced expression of HPA axis elements were observed. The reduced expression of HPA axis elements and melanogenesis in the skin of stressed mice were reversed by RU486 (a glucocorticoid receptor antagonist) treatment. Glucocorticoids had no significant inhibitory effect on melanogenesis in vitro. These results suggest that, high levels of serum corticosterone induced by chronic stress can reduce the expression of elements of the skin HPA axis by glucocorticoid-dependent negative feedback. These activities can eventually result in decreased skin pigmentation. Our findings raise the possibility that chronic stress could be a risk factor for depigmentation by disrupting the cutaneous HPA axis and should prompt dermatologists to exercise more caution when using glucocorticoids for treatment

DPC-MSGATNet : dual-path chain multi-scale gated axial-transformer network for four-chamber view segmentation in fetal echocardiography

Echocardiography is essential in evaluating fetal cardiac anatomical structures and functions when clinicians conduct early treatment and screening for congenital heart defects, a common and intricate fetal malformation. Nevertheless, the prenatal detection rate of fetal CHD remains low since the peculiarities of fetal cardiac structures and the variousness of fetal CHD. Precisely segmenting four cardiac chambers can assist clinicians in analyzing cardiac morphology and further facilitate CHD diagnosis. Hence, we design a dual-path chain multi-scale gated axial-transformer network (DPC-MSGATNet) that simultaneously models global dependencies and local visual cues for fetal ultrasound (US) four-chamber (FC) views and further accurately segments four chambers. Our DPC-MSGATNet includes a global and a local branch that simultaneously operates on an entire FC view and image patches to learn multi-scale representations. We design a plug-and-play module, Interactive dual-path chain gated axial-transformer (IDPCGAT), to enhance the interactions between global and local branches. In IDPCGAT, the multi-scale representations from the two branches can complement each other, capturing the same region’s salient features and suppressing feature responses to maintain only the activations associated with specific targets. Extensive experiments demonstrate that the DPC-MSGATNet exceeds seven state-of-the-art convolution- and transformer-based methods by a large margin in terms of F1 and IoU scores on our fetal FC view dataset, achieving a F1 score of 96.87% and an IoU score of 93.99%. The codes and datasets can be available at https://github.comQiaoSiBo/DPC-MSGATNet

Time table of the experiments.

<p>CRS or CUMS was administered beginning on day 1 and continued for 21 days. Drugs were also administered from day 1 for 21 days. All mice received epilation to induce anagen of the hair cycle at day 9. Mice were photographed on days 10 and 22, which were 2 and 13 days post-depilation. Tissue samples were collected on day 22.</p

Chronic stress causing reduction of melanogenesis in mice dorsal skin.

<p><b>A</b>: Photographs of mice back skin on day 2 and day 13 after epilation showing the reduction of melanin in the skin of CRS and CUMS group mice on day 13. <b>B</b>: The mRNA expression levels of microphthalmia-associated transcription factor (MITF) in mouse skin. <b>C</b>: The mRNA expression levels of tyrosinase (TYR) in mouse skin. The expression levels of each gene were normalized against β-Actin then calculated as fold change using the comparative 2^-ΔΔCT method. Data are showed in mean ± SEM, n = 8, and the data were analyzed by one-way ANOVA with Tukey's post hoc test. * <i>P<0.05</i>, ** <i>P<0.01</i>, *** <i>P<0.001</i>, compared with control.</p

Effects of HPA axis-related hormones on melanin synthesis in vitro.

<p><b>A</b>: Measurement of melanin contents in normal human epidermal melanocytes (NHEMs) after treatment with 50 nM α-MSH or 1 µM DEX for 72 h. <b>D</b>: Measurement of melanin contents in B16F10 cells after treatment with 50 nM α-MSH or 1 µM DEX for 72 h. <b>B–C</b>: The mRNA expression levels of MITF and TYR in NHEMs after treatment with 50 nM α-MSH or 1 µM DEX for 24 h. <b>E–F</b>: The mRNA expression levels of MITF and TYR in B16F10 cells after treatment with 50 nM α-MSH or 1 µM DEX for 24 h. The expression levels of each gene were normalized against β-Actin or GAPDH then calculated as fold change using the comparative 2^-ΔΔCT method. Data are combined from three separate experiments and showed in mean ± SEM, and the data were analyzed by one-way ANOVA with Tukey's post hoc test. * <i>P<0.05</i>, ** <i>P<0.01</i>, *** <i>P<0.001</i>, compared with control; ^&&<i>P<0.01</i>, compared with α-MSH.</p

Effects of RU486 on the dorsal skin of stressed mice.

<p><b>A</b>: Photographs of mice back skin on day 2 and day 13 after epilation showing that the mice received RU486 injection had a significantly darker observable skin color than CUMS mice. <b>B</b>: MITF expression was analyzed by immunoblotting. <b>C</b>: TYR expression was analyzed by immunoblotting. <b>D</b>: POMC expression was analyzed by immunoblotting. β-Actin expression was indicated as a loading control. Western blot assay are representative of three experiments. Densitometric scanning of band intensities obtained from three separate experiments was used to quantify change of proteins expression. Three animals were used for each data point. Data are showed in mean ± SEM. <b>E</b>: The mRNA expression levels of UCN1, POMC, and CYP11A1 in mouse skin. The expression levels of each gene were normalized against β-Actin then calculated as fold change using the comparative 2^-ΔΔCT method. Data are showed in mean ± SEM, n = 8. The data were analyzed by one-way ANOVA with Tukey's post hoc test. * <i>P<0.05</i>, *** <i>P<0.001</i>, compared with control; ^&<i>P<0.05</i>, ^&&<i>P<0.01</i>, ^&&&<i>P<0.001</i>, compared with CUMS.</p

Primer sequences.

<p>Primer sequences.</p

Chronic stress causing disrupted expressions of cutaneous HPA axis elements.

<p><b>A</b>: POMC expression was analyzed by immunoblotting. β-Actin expression was indicated as a loading control. Western blot assay are representative of three experiments. Densitometric scanning of band intensities obtained from three separate experiments was used to quantify change of proteins expression. Three animals were used for each data point. Data are showed in mean ± SEM. <b>B–K</b>: The mRNA expression levels of POMC, UCN1, MC1R, MC2R, CRHR1, CRHR2, CYP11A1, Hsd11b1, Hsd11b2, and Nr3c1 in mouse skin. The expression levels of each gene were normalized against β-Actin then calculated as fold change using the comparative 2^-ΔΔCT method. Data are showed in mean ± SEM, n = 8. Data were analyzed by one-way ANOVA with Tukey's post hoc test. * <i>P<0.05</i>, ** <i>P<0.01</i>, compared with control.</p