Gene expression of estrogen and oxytocin receptors in the uterus of pregnant and parturient bitches

In the canine species, the precise mechanisms of pregnancy maintenance and the initiation of parturition are not completely understood. The expression of genes encoding the receptors for estrogen (ERα mRNA) and oxytocin (OTR mRNA) was studied in the endometrium and myometrium during pregnancy and parturition in dogs. Real-time PCR was performed to quantify the levels of ERα mRNA and OTR mRNA in the uterus of bitches during early (up to 20 days of gestation), mid (20 to 40 days) and late pregnancy (41 to 60 days), and parturition (first stage of labor). All tissues expressed ERα and OTR mRNA, and are thus possibly able to respond to eventual estrogen and oxytocin hormonal stimuli. No statistically significant differences in the expression of ERα mRNA were verified in the endometrium and myometrium throughout pregnancy and parturition, but expression of OTR mRNA increased at both parturition and late pregnancy. We concluded that the increase of endometrial and myometrial OTR mRNA expression in dogs is not an event dependent on estrogenic stimulation. Moreover, the contractility response of the canine uterus to oxytocin begins during pregnancy and maintains myometrial activity. The expression of OTR mRNA in canine uterine tissues varied over time, which supports an interpretation that the sensitivity and response to hormone therapy varies during the course of pregnancy and labor. Further studies are needed to elucidate the factors underlying the synthesis of uterine oxytocin receptors and the possible role of ERβ rather than ERα in the uterine tissues during pregnancy and parturition in dogs.

Expression of estrogen and progesterone receptor genes in endometrium, myometrium and vagina of postmenopausal women treated with estriol / Expresión de los genes receptores de estrógeno y progesterona en el endometrio, miometrio y vagina en mujeres posmenopáusicas tratadas con estriol

CONTEXT AND OBJECTIVE: Estriol is an estrogen with considerably weaker stimulatory effects on endometrial proliferation than estradiol. A study was conducted to determine the level of estrogen receptors (ERs) and progesterone receptors (PRs) in women who received 14-day vaginal estriol therapy, compared with those who did not receive this therapy. ER and PR gene expression was analyzed in the endometrium, myometrium and vagina of postmenopausal women treated with estriol. DESIGN AND SETTING: Analytical cross-sectional study, at the Research Institute of the Polish Mothers' Memorial Hospital, Lodz, Poland. METHODS: Twenty-seven postmenopausal women (57-74 years of age) were included in the study. All of them were waiting for per vaginam hysterectomy or plastic surgery on the vagina and perineum because of uterine prolapse. ER and PR gene expression was determined by means of the technique of reverse transcription polymerase chain reaction (RT-PCR). RESULTS: In the estriol-treated patients, in comparison with the control group, a significant increase in ER gene expression was observed in the endometrium and vagina, while enhanced PR gene expression was found in the endometrium. However, under histological examination of the endometrium, estrogen stimulation of low and medium degree was diagnosed for 21.4 percent and 14.3 percent of the estriol-treated women, respectively. CONCLUSION: The results obtained suggest that the women who received 14 days of treatment with vaginal estriol had higher ER and PR mRNA levels. No difference between these groups regarding endometrial proliferation was observed.

CONTEXTO Y OBJETIVO: El estriol es un estrógeno con un efecto estimulatorio bastante más débil sobre la proliferación endometrial que el estradiol. Se realizó un estudio para determinar los efectos de una terapia vaginal de 14 días con estriol, sobre el nivel de receptores de estrógeno (ER) y receptores de progesterona (PR), comparado con mujeres sin esa terapia. La expresión de los genes de ER y PR se analizó en el endometrio, miometrio y vagina de mujeres posmenopáusicas tratadas con estriol. DISEÑO Y UBICACIÓN: Estudio Transversal analítico, en el Instituto de Investigación del Hospital de la Madre Polaca en Lodz, Polonia. MÉTODOS: Se incluyeron veintisiete mujeres posmenopáusicas (de 57 a 74 años) en el estudio. Todas ellas estaban en espera de una histerectomía per vaginam o de cirugía plástica de la vagina y del perineo debido a un prolapso del útero. La expresión de genes de los receptores ER y PR se estableció por la técnica de RT-PCR. RESULTS: En las pacientes tratadas con estriol en comparación con el grupo de control, se observó un aumento significativo de la expresión del gen de ER en el endometrio y la vagina, mientras que un aumento de la expresión del gen de PR se encontró en el endometrio. De todas formas, en el examen histológico del endometrio, se diagnosticó estimulación estrogénica de bajo y medio grado en el 21.4 por ciento y en el 14.3 por ciento de las mujeres tratadas con estriol, respectivamente. CONCLUSIONES: Los resultados obtenidos sugieren que un tratamiento de 14 días con estriol en pacientes, aunque aumentan el nivel de ER y de PR mRNA, tiene muy poco o ningún efecto sobre la proliferación endometrial.

Modulation of store-operated Ca2+ entry by cyclic-ADP-ribose

Store-operated Ca2+ entry plays an important role in Ca2+ homeostasis in cells but the mechanisms of control of these channels are not completely understood. We describe an investigation of the role of the CD38-cyclic-ADP-ribose (cADPR)-ryanodine-channel (RyR) signaling pathway in store-operated Ca2+ entry in human smooth muscle. We observed that human myometrial cells have a functional store-operated Ca2+ entry mechanism. Furthermore, we observed the presence of transient receptor potential 1, 3, 4, 5, and 6 ion channels in human myometrial cells. Store-operated Ca2+ transient was inhibited by at least 50-70 percent by several inhibitors of the RyR, including ryanodine (10 µM), dantrolene (10 µM), and ruthenium red (10 µM). Furthermore, the cell permeable inhibitor of the cADPR-system, 8-Br-cADPR (100 µM), is a potent inhibitor of the store-operated entry, decreasing the store operated entry by 80 percent. Pre-incubation of cells with 100 µM cADPR and the hydrolysis-resistant cADPR analog 3-deaza-cADPR (50 µM), but not with ADP-ribose (ADPR) leads to a 1.6-fold increase in the store-operated Ca2+ transient. In addition, we observed that nicotinamide (1-10 mM), an inhibitor of cADPR synthesis, also leads to inhibition of the store-operated Ca2+ transient by 50-80 percent. Finally, we observed that the transient receptor potential channels, RyR, and CD38 can be co-immunoprecipitated, indicating that they interact in vivo. Our observations clearly implicate the CD38-cADPR-ryanodine signaling pathway in the regulation of store-operated Ca2+ entry in human smooth muscle cells.

Expression of cyclooxygenase-2 mRNA and identification of its splice variant in human myometrium obtained from women in labor / 华中科技大学学报（医学）（英德文版）

In order to investigate the expression of cyclooxygenase-2 (COX-2) in human lower segments of myometrium obtained from women in labor and those not in labor and identify the splicing variant of COX-2, reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the expression of COX-2. The primers were designed and synthesized according to the sequence of rat COX-2 splice variant which was discovered firstly by us. Then the splicing variant of COX-2 in human myometrium from woman in labor was identified, cloned into vector and sequenced. The results showed that the expression of COX-2 mRNA was lower in human myometrium obtained from women who were not in labor than that in labor women and a new band of COX-2 was obtained in myometrium from labor woman. The fragment included an unspliced intron, which pitched between exons 7 and 8. It was suggested that COX-2 gene was not only expressed highly in human myometrium from woman in labor, but also produced splicing variant by alternative splicing.

Ca2+ entry, efflux and release in smooth muscle

Control of smooth muscle is vital for health. The major route to contraction is a rise in intracellular [Ca2+], determined by the entry and efflux of Ca2+ and release and re-uptake into the sarcoplasmic reticulum (SR). We review these processes in myometrium, to better understand excitation-contraction coupling and develop strategies for preventing problematic labours. The main mechanism of elevating [Ca2+] is voltage-gated L-type channels, due to pacemaker activity, which can be modulated by agonists. The rise of [Ca2+] produces Ca-calmodulin and activates MLCK. This phosphorylates myosin and force results. Without Ca2+ entry uterine contraction fails. The Na/Ca exchanger (NCX) and plasma membrane Ca-ATPase (PMCA) remove Ca2+, with contributions of 30 percet and 70 percet respectively. Studies with PMCA-4 knockout mice show that it contributes to reducing [Ca2+] and relaxation. The SR contributes to relaxation by vectorially releasing Ca2+ to the efflux pathways, and thereby increasing their rates. Agonists binding produces IP3 which can release Ca from the SR but inhibition of SR Ca2+ release increases contractions and Ca2+ transients. It is suggested that SR Ca2+ targets K+ channels on the surface membrane and thereby feedback to inhibit excitability and contraction.

Application of electron spin resonance for evaluation of the level of free radicals in the myometrium in full-term pregnancy with normal labour and uterine inertia.

In order to identify and quantify free radicals in the tissues of patients with normal physiological and pathological states of births, we developed a method to evaluate the amount of free radicals in myometrium of subplacental area and from body of uterus, using electron spin resonance spectroscopy. Analysis of the concentration of free radicals in the myometrium in full-term pregnancy with normal labour and during uterine inertia was studied. The activities of Ca2+-ATPase, cytochrome c oxidase and succinate dehydrogenase in samples of these tissues were tested too. Low free radical concentrations in these tissues were associated with disturbances in contractile activity of myometrium along with reduction of Ca2+-ATPase, cytochrome c oxidase and succinate dehydrogenase activity. There proved to be an association between the level of free radicals in the tissues and alteration in the physiological processes.

Galactosaminoglycans from normal myometrium and leiomyoma

In many tumors, the amount of chondroitin sulfate in the extracellular matrix has been shown to be elevated when compared to the corresponding normal tissue. Nevertheless, the degree of chondroitin sulfate increase varies widely. In order to investigate a possible correlation between the amount of chondroitin sulfate and tumor size, several individual specimens of human leiomyoma, a benign uterine tumor, were analyzed. The glycosaminoglycans from eight tumors were extracted and compared with those from the respective adjacent normal myometrium. The main glycosaminoglycan found in normal myometrium was dermatan sulfate, with small amounts of chondroitin sulfate and heparan sulfate. In leiomyoma, both dermatan sulfate and chondroitin sulfate were detected and the total amounts of the two galactosaminoglycans was increased in all tumors when compared to normal tissue. In contrast, the heparan sulfate concentration decreased in the tumor. To assess the disaccharide composition of galactosaminoglycans, these compounds were incubated with bacterial chondroitinases AC and ABC. The amounts of L-iduronic acid-containing disaccharides remained constant, whereas the concentration of D-glucuronic acid-containing disaccharides increased from 2 to 10 times in the tumor, indicating that D-glucuronic acid-containing disaccharides are responsible for the elevation in galactosaminoglycan concentration. This increase is positively correlated with tumor size

Induction of c-Jun mRNA without changes of estrogen and progesterone receptor expression in myometrium during human labor

To elucidate the endocrine mechanism of human parturition, the expression of c-Jun and c-Fos mRNA were examined in relation to estrogen receptor (ER) and progesterone receptor (PR) in human myometrium. c-Jun mRNA was detected in all myometrial tissues (n=5) during labor but not before labor (n=5) and in oxytocin-resistant postterm pregnancy (n=3). c-Fos mRNA was detected in only one myometrial tissue from a woman in labor. The distribution and intensity of immunostaining for ER and PR were semiquantitatively scored. During the late pregnancies, no significant difference was seen in the receptor scores for myometrial ER and PR between the patients who experienced labor and those who did not. Receptor scores for ER and PR were significantly lower in postterm pregnancy than in late pregnancy, regardless of the labor status. These data suggest that there are no changes in ER and PR in human myometrium during parturition. On the other hand, postterm pregnancy is associated with low ER and PR. c-Jun, induced during labor without changes in ER and PR, may play a role as a signaling mechanism in human myometrium.

Importância do fator de crescimento epidérmico (EGF) e seu receptor (EGF-R) no tecido endometrial / Epidermal growth factor (EGF) and its receptor (EGF-R) importance in the endometrial tissue

Os autores fazem uma revisäo sobre a influência que o EGF e seu receptor (EGF-R) exercem no tecido endometrial, enfocando sua possível regulaçäo pelos esteróides e seus receptores e sua importância nos processos de transformaçäo secretora e de decidualizaçäo.