cAMP regulates the progesterone receptor gene expression through the protein kinase A pathway during decidualization in human immortalized endometrial stromal cells.

Decidualization, a crucial process for successful pregnancy establishment and maintenance, involves endometrial stromal cell differentiation. This process is orchestrated by estradiol (E2), progesterone, and other stimuli that increase intracellular cyclic adenosine monophosphate (cAMP) levels. The intracellular progesterone receptor (PR), encoded by the PGR gene, has a key role in decidualization. This study aimed to understand the role of sex steroids and cAMP in regulating PGR expression during the in vitro decidualization of the human immortalized endometrial stromal cell line, T-HESC. We subjected the cells to individual and combined treatments of E2, medroxyprogesterone (MPA), and cAMP. Additionally, we treated cells with PR and estrogen receptor antagonists and a protein kinase A (PKA) inhibitor. We evaluated the expression of PGR isoforms and decidualization-associated genes by RT-qPCR. Our findings revealed that cAMP induced PGR-B and PGR-AB expression by activating the PKA signaling pathway, while MPA downregulated their expression through the PR. Furthermore, downstream genes involved in decidualization, such as those coding for prolactin (PRL), insulin-like growth factor-binding protein-1 (IGFBP1), and Dickkopf-1 (DKK1), exhibited positive regulation via the cAMP-PKA pathway. Remarkably, MPA-activated PR signaling induced the expression of IGFBP1 and DKK1 but inhibited that of PRL. In conclusion, we have demonstrated that the PKA signaling pathway induces PGR gene expression during in vitro decidualization of the T-HESC human endometrial stromal cell line. This study has unraveled some of the intricate regulatory mechanisms governing PGR expression during this fundamental process for implantation and pregnancy maintenance.

Unilateral lesion of the suprachiasmatic nucleus impairs estradiol feedback, follicular development, estrous cycle and ovulation.

In brief: The SCN regulates ovulation by stimulating the preovulatory surge of gonadotropins. This study revealed an additional role in the sensitization of the hypothalamus to estradiol that changes along the estrous cycle and the side of the nucleus. Abstract: Ovulation is timed by neural signals originating at the suprachiasmatic nucleus (SCN) that trigger ovulation when converge with high estradiol levels, which indicates the maturation of ovarian follicles. We have shown that the hypothalamic regulation of ovulation is asymmetrical and we hypothesized that the paired SCN could contribute to such symmetries. We unilaterally lesioned the SCN of rats at each stage of the estrous cycle and evaluated the acute effects on the progression of their estrous cycle, follicular development and ovulation. Lesions prevented progression of the estrous cycle when performed in estrus/metestrus but not in diestrus/proestrus. Abnormalities in follicular development were observed in the nonovulating lesioned rats and this was independent of the side of the SCN destroyed and the stage of the cycle when surgery was performed. Groups of lesioned rats were then hormonally primed with GnRH or estradiol to assess the neuroendocrine pathway altered by the treatment. GnRH restored ovulation, suggesting that both SCN are needed for proper triggering of the preovulatory surge of GnRH and that unilateral lesion does not impair the sensitivity of the pituitary or the ovary to GnRH and gonadotropins, respectively. With regard to restoring ovulation, estradiol was asymmetrically effective in rats lesioned in estrous, partially effective in rats operated at diestrus and ineffective in rats at metestrus. Our results indicate that the SCN regulates the activity of the hypothalamic-pituitary-ovarian axis not only by modulating the preovulatory surge of GnRH/gonadotropins but also by promoting the hypothalamic integration of estrogenic signals from the ovaries in an asymmetric and stage-dependent fashion.

Differential localization of serotoninergic system elements in human amniotic epithelial cells†.

Serotonin or 5-hydroxytryptamine (5-HT) is a biogenic amine involved in regulating several functions, including development. However, its impact on human embryo development has been poorly studied. The present work investigated the expression and distribution of the main components of the serotoninergic system in human amniotic tissue and human amniotic epithelial cells (hAEC) in vitro, as an alternative model of early human embryo development. Amniotic membranes from full-term healthy pregnancies were used. Human amnion tissue or hAEC isolated from the amnion was processed for reverse transcription-polymerase chain reaction and immunofluorescence analyses of the main components of the serotoninergic system. We found the expression of tryptophan hydroxylase type 1 (TPH1), type 2 (TPH2), serotonin transporter (SERT), monoamine oxidase-A (MAOA), as well as HTR1D and HTR7 receptors at mRNA level in amnion tissue as well in hAEC. Interestingly, we found the presence of 5-HT in the nucleus of the cells in amnion tissue, whereas it was located in the cytoplasm of isolated hAEC. We detected TPH1, TPH2, and HTR1D receptor in both the nucleus and cytoplasm. SERT, MAOA, and HTR7 receptor were only observed in the cytoplasm. The results presented herein show, for the first time, the presence of the serotoninergic system in human amnion in vivo and in vitro.

Role of serotonin in vertebrate embryo development.

Since its discovery in 1937, serotonin (5-HT) has become one of the most studied biogenic amines due to its predominant role in regulating several physiological processes such as mood, sleep, and food intake. This amine and the main components of the serotoninergic system are in almost all cells of the body. The presence of 5-HT and the serotoninergic system has been observed in oocytes and in different embryo development stages of fish, amphibians, birds, and mammals. In several classes of vertebrates, the change in the concentration of 5-HT or the alteration of the serotoninergic system, interfere with early embryo development. These data suggest that 5-HT participates in embryo development of vertebrates.

Inhibition of serotonin reuptake in the prepubertal rat ovary by fluoxetine and effects on ovarian functions.

Fluoxetine (FLX), a selective serotonin reuptake inhibitor is an antidepressant in the treatment of mood disorders. Its impact on reproductive processes is incompletely known. The present study analyzed the reproductive effects of FLX in prepubertal female rats. Two experiments were conducted. First (acute administration), 30-day-old female rats were injected intraperitoneally with 5mg/kg of fluoxetine-hydrochloride, and were terminated 24, 48 or 72h after the treatment. Second (subchronic administration), FLX was injected on days 30-33 of age, and the animals were terminated the day of first estrus. In acute treatment estradiol concentration increased to 72h. In subchronic treatment increased serotonin concentration in ovaries and decreased the number of ova shed. An increase in number of atretic follicles and oocyte fragmentation was observed in these animals. The results suggest that FLX acts on the ovary or hypothalamus-pituitary axis resulting in modifications of the follicular development and ovulation.