Retinoic acid inhibition of cell proliferation via activation of CDKN1B signaling in the forebrain and spinal cord during mouse embryonic development

Abstract

Background: The active metabolite of vitamin A (retinol) is retinoic acid (RA). RA is essential for developing several organs as a signaling molecule that is tightly regulated during embryogenesis. We explored the teratogenic effects of RA on forebrain and spinal cord development modified by cyclin-dependent kinase inhibitor 1B (CDKN1B), as the mechanism underlying RA's teratogenic impacts requires further investigation. The study involved four groups of pregnant mice: the negative control group, the positive control group treated with dimethyl sulfoxide (DMSO) diluted in sunflower oil, the RA-treated group receiving a low dosage (5 mg/kg), and the RA-treated group receiving a high dosage (10 mg/kg). The treatment groups received daily intraperitoneal RA dissolved in DMSO and diluted with sunflower oil on gestational days 10.5, 11.5, and 12.5. On day 13.5 of pregnancy, the pregnant mice were euthanized by cervical dislocation, and immunohistochemical analyses of brain and spinal cord tissues were performed. Results: Morphologically, we observed a decrease in the number of implantation sites and the presence of hematomas in several uterus areas in the high-dose RA (10 mg/kg) group. Additionally, RA was shown to cause adverse changes in uterine weight and length. RA treatment indicated elevated levels of CDKN1B expression in spinal cord development, the diencephalon, and the telencephalon. Conclusion: Our findings demonstrated that by activating CDKN1B as an RA target gene for cell cycle arrest, an excess of RA during brain development in mouse embryos can induce cell undifferentiation during development.