Thyroid Hormone Receptors in Human Skin during Aging

Abstract

This work was aimed to study levels of thyroid hormone receptors in human dermal fibroblasts from the development to deep aging. Skin specimens from human fetuses died antenatally from 20 to 40 weeks of pregnancy, humans died from different causes from birth to 85 years of life were used for the study. Total number of fibroblasts, percent of proliferating cells nuclear antigen (PCNA) positive dermal fibroblasts, expression of thyroid hormone receptors-α and -β in dermal fibroblasts were examined. PCNA and thyroid hormone receptors were viewed immunohistochemically. A total number of fibroblasts in dermis were counting in sections stained with haematoxylin and eosin. Results showed that maximal levels of thyroid hormone receptors-α and -β were observed from 20 to 40 weeks of pregnancy. The levels of thyroid hormone receptors-α and -β were decreased from birth to 40 years of life. From 41 to 85 years, the levels of thyroid hormone receptors were approximately the same. A total number and percent of PCNA positive fibroblasts in dermis decreased with progression of age. Most sufficient age-dependent reduction in a total and PCNA positive number of dermal fibroblast was observed from antenatal until 40 years of life. Correlation analysis and one-way ANOVA showed that age-dependent decrease in the number of fibroblasts and retardation of their proliferation in human dermis is significantly associated with age-related decrease in the level of thyroid hormone receptors-α and -β in dermal fibroblasts. Results allow to suggest that thyroid hormone receptors are involved in age-dependent decrease in the number and proliferation of fibroblasts in human dermis.