Adrenarche is characterized by the increase in adrenal androgen production, namely dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEAS) that occurs around 6 years of age. These steroids are secreted by the zona reticularis (ZR) of the adrenal gland. This is associated with pubarche or the increase in androgen-dependent hair growth at the time of puberty. The increase in adrenal androgen production can be explained by the increase in the expression of DHEA-synthesizing steroidogenic enzymes in the ZR. Adrenarche is an event independent of gonadarche and is found only in humans and select nonhuman primates. Although numerous prenatal and postnatal factors are important in the onset of adrenarche, a specific adrenal cortical androgen-stimulating hormone has not been identified. Evidence also exists for a role for adrenarche in behavior, skeletal maturation, and postpubertal well-being. Adrenarche is influenced by sex and race, and some of this variation may be related to the insulin and insulin-like growth factor (IGF) signaling pathways. In addition, children with premature and exaggerated adrenarche may be predisposed to certain diseases later in life.
Identification of temporal and spatial changes in myometrial gene expression during parturition may further the understanding of the coordinated regulation of myometrial contractions during parturition. The objective of this study was to compare the gene expression profiles of human fundal myometrium from pregnant women before and after the onset of labor using a functional genomics approach, and to further characterize the spatial and temporal expression patterns of three genes believed to be important in parturition. Fundal myometrial mRNA was isolated from five women in labor and five women not in labor, and analyzed using human UniGEM-V microarrays with 9182 cDNA elements. Real-time polymerase chain reaction using myometrial RNA from pregnant women in labor or not in labor was used to examine mRNA levels for three of the genes; namely, prostaglandin-endoperoxide synthase 2 (PTGS2), calgranulin B (S100A9), and oxytocin receptor (OXTR). The spatial expression pattern of these genes throughout the pregnant uterus before and after labor was also determined. Immunolocalization of cyclooxygenase-2 (also known as PTGS2) and S100A9 within the uterine cervix and myometrium were analyzed by immunohistochemistry. Few genes were differentially expressed in fundal myometrial tissues at term with the onset of labor. However, there appears to be a subset of genes important in the parturition cascade. The cellular properties of S100A9, its spatial localization, and dramatic increase in cervix and myometrium of women in labor suggest that this protein may be very important in the initiation or propagation of human labor.
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