Perinatal hypothyroidism impairs cerebellar organogenesis and results in motor coordination defects. The thyroid hormone receptor binds to corepressor complexes containing histone deacetylase (HDAC) 3 in the absence of ligands and acts as a transcriptional repressor. Although histone acetylation status is strongly correlated with transcriptional regulation, its role in cerebellar development remains largely unknown. We aimed to study whether the cerebellar developmental defects induced by perinatal hypothyroidism can be rescued by treatment with a specific HDAC3 inhibitor, RGFP966. Motor coordination was analyzed using three behavioral tests. The cerebella were subjected to RT-qPCR and chromatin immunoprecipitation assays for acetylated histone H3. The treatment with RGFP966 partially reversed the cerebellar morphological defects in perinatal hypothyroid mice. These findings were associated with the alleviation of motor coordination defects in these mice. In addition, the RGFP966 administration increased the mRNA levels of cerebellar thyroid hormone-responsive genes. These increases were accompanied by augmented histone acetylation status at these gene loci. These findings indicate that HDAC3 plays an important role in the cerebellar developmental defects induced by perinatal hypothyroidism. The HDAC3 inhibitor might serve as a novel therapeutic agent for hypothyroidism-induced cerebellar defects by acetylating histone tails and stimulating transcription at thyroid hormone-responsive gene loci.

Background: The spread of the coronavirus disease (COVID-19) has significantly affected medical education. In particular, conducting practical training in a face-to-face format has become difficult. Purpose: To address this problem, online physiology practice combined with team-based learning (TBL) for deep learning of renal physiology was conducted among second-year medical students. Participants and Methods: The experiment was performed by a group of students, while other students watched online. After the experiment, all students were grouped using breakout rooms. Following a discussion of the data, a clinical case study related to the experiment was conducted using TBL. To examine the effect of online practice in a case study under TBL, the participants completed an anonymous, open-ended, web-based questionnaire after the program, enabling us to compare their expectations and satisfaction. The questionnaire consisted of questions examining students’ opinions on the appropriateness of online practice, degree of understanding, ease of asking questions, time efficiency, and the usefulness of case studies using TBL. Results: There was no change in the number of students who participated in the online practice before and after class. After class, more students considered the level of understanding easier and displayed better on-time efficiency than with regular face-to-face training. However, these questions are difficult to answer. Conclusion: Online-based physiology practice combined with clinical case studies under TBL helped maintain students’ expectations and satisfaction with the training.

Perfluorooctane sulfonate (PFOS) has been used in a wide variety of industrial and commercial products. The adverse effects of PFOS on the developing brain are becoming of a great concern. However, the molecular mechanisms of PFOS on brain development have not yet been clarified. We investigated the effect of early-life exposure to PFOS on brain development and the mechanism involved. We investigated the change in thyroid hormone (TH)-induced dendrite arborization of Purkinje cells in the primary culture of newborn rat cerebellum. We further examined the mechanism of PFOS on TH signaling by reporter gene assay, quantitative RT-PCR, and type 2 iodothyronine deiodinase (D2) assay. As low as 10⁻⁷ M PFOS suppressed thyroxine (T₄)-, but not triiodothyronine (T₃)-induced dendrite arborization of Purkinje cells. Reporter gene assay showed that PFOS did not affect TRα1- and TRβ1-mediated transcription in CV-1 cells. RT-PCR showed that PFOS suppressed D2 mRNA expression in the absence of T₄ in primary cerebellar cells. D2 activity was also suppressed by PFOS in C6 glioma-derived cells. These results indicate that early-life exposure of PFOS disrupts TH-mediated cerebellar development possibly through the disruption of D2 activity and/or mRNA expression, which may cause cerebellar dysfunction.

Estrogen plays an important role in osteoporosis prevention. We herein report the possible novel signaling pathway of 17β-estradiol (E2) in the matrix mineralization of MC3T3-E1, an osteoblast-like cell line. In the culture media-containing stripped serum, in which small lipophilic molecules such as steroid hormones including E2 were depleted, matrix mineralization was significantly reduced. However, the E2 treatment induced this. The E2 effects were suppressed by ICI182,780, the estrogen receptor (ER)α, and the ERβ antagonist, as well as their mRNA knockdown, whereas Raloxifene, an inhibitor of estrogen-induced transcription, and G15, a G-protein-coupled estrogen receptor (GPER) 1 inhibitor, had little or no effect. Furthermore, the E2-activated matrix mineralization was disrupted by PMA, a PKC activator, and SB202190, a p38 MAPK inhibitor, but not by wortmannin, a PI3K inhibitor. Matrix mineralization was also induced by the culture media from the E2-stimulated cell culture. This effect was hindered by PMA or heat treatment, but not by SB202190. These results indicate that E2 activates the p38 MAPK pathway via ERs independently from actions in the nucleus. Such activation may cause the secretion of certain signaling molecule(s), which inhibit the PKC pathway. Our study provides a novel pathway of E2 action that could be a therapeutic target to activate matrix mineralization under various diseases, including osteoporosis.

Thyroid hormones (THs) and estrogen (E2) play essential roles in neuronal differentiation and plasticity during brain development. S-equol, a plant-derived isoflavone metabolite, is a selective E2 receptor (ER) ligand that exhibits neurotrophic effects; however, its interaction with TH receptor (TR) signaling remains unclear. In this study, we investigated the effects of S-equol on TRβ-associated transcriptional activity and neuronal morphogenesis in mouse neuroblastoma-derived Neuro-2a cells or rat C6 glioma cells. Luciferase reporter assays demonstrated that S-equol significantly enhanced T3-induced TRβ transcriptional activity in a concentration- and time-dependent manner. Additionally, exposure to S-equol or T3 alone promoted neurite outgrowth and wound closure, whereas co-exposure to both compounds resulted in a more significant enhancement of these processes. Furthermore, mRNA expression levels of synapse-related genes (Dlg4, Syn1, Syp, Camk2b, and Bdnf) were significantly increased by S-equol co-exposure in the presence of T3. In silico docking analysis revealed that S-equol exhibited moderate to high binding affinity for TRβ (−8.7 kcal/mol), ERα, and ERβ, suggesting a structural basis for TR–ER crosstalk. Collectively, these findings indicate that S-equol functions as a dual-acting modulator that may modulate T3 signaling involving TR–ER interaction. Although S-equol may exert beneficial effects on neurodevelopment, it may also act as an endogenous endocrine modulator that alters the fine regulation of TH action during development, warranting careful evaluation from physiological and toxicological perspectives.

The placenta secretes a prolactin (PRL)-like hormone PRL3B1 (placental lactogen II), a luteotropic hormone essential for maintaining pregnancy until labor in mice. A report from 1984 examined the secretion pattern of PRL3B1 in prepartum mice. In the current study, we found contradictory findings in the secretion pattern that invalidate the previous report. By measuring maternal plasma PRL3B1 and PRL every 4 hrs from gestational day 17 (G17), we newly discovered that maternal plasma PRL3B1 levels decrease rapidly in prepartum C57BL/6 mice. Interestingly, the onset of this decline coincided with the PRL surge at G18, demonstrating a plasma prolactin axis shift from placental to pituitary origin. We also found that maternal plasma progesterone regression precedes the onset of the PRL shift. The level of Prl3b1 mRNA was determined by RT-qPCR in the placenta and remained stable until parturition, implying that PRL3B1 peptide production or secretion was suppressed. We hypothesized that production of the PRL family, the 25 paralogous PRL proteins exclusively expressed in mice placenta, would decrease alongside PRL3B1 during this period. To investigate this hypothesis and to seek proteomic changes, we performed a shotgun proteome analysis of the placental tissue using data-independent acquisition mass spectrometry (DIA-MS). Up to 5,891 proteins were identified, including 17 PRL family members. Relative quantitative analysis between embryonic day 17 (E17) and E18 placentas showed no significant difference in the expression of PRL3B1 and most PRL family members except PRL7C1. These results suggest that PRL3B1 secretion from the placenta is suppressed at G18 (E18).