Thyroid hormones affect the proliferation and/or mobilization of bulge stem cell population

Introduction. Thyroid hormones (TH) play a pivotal role in the development of mammalian skin and are necessary for both, the initiation and maintenance of hair growth. Hypothyroid rats showed impaired epidermal proliferation, hair growth, and wound healing. Stem cells located at the bulges of the hair follicles are responsible for hair cycling and contribute to the regeneration of the new epidermis after wounding. Therefore a reduction in the num¬ber or function of the bulge stem cells could be responsible for this phenotype. We hypothesized that decrease in TH during prenatal development would affect bulge stem cell population. Material and methods. Subclinical hypothyroidism was induced with propylthiouracil through drinking water in dose 1.5 mg/l in pregnant Albino Oxford rats from the first day of gravidity. Control group was untreated. Seven-day-old pups were euthanized and skin samples were taken from dorsal part of their bodies. For the immunohistochemical study PCNA (Santa Cruz Biotechnology) and NANOG (Thermo scientific) antibodies were used. Results. . The number of hair follicles was reduced in hypothyroid pups compared to controls. They also had a decreased expression of PCNA in cells of inner and outer sheat of hair follicles, but increased number of NANOG positive bulge stem cells. Conclusion. This suggests that re¬duced activation of stem cells leading to their accumulation in the bulges which is associated with reduced stem cell prolif¬eration and mobilization.Book of Abstract