Human myometrial contraction plays a fundamental role in labor. Dysfunction of uterine contraction is an important cause of labor progression failure. Although the mechanisms controlling uterine contraction are not completely understood, intracellular Ca2+ mobilization plays an important role during uterine contraction. Several mechanisms of intracellular Ca2+ mobilization are present in smooth muscle, but in the human uterus, only 1,4,5-trisphosphate-induced Ca2+ release has been studied extensively. Ryanodine receptor channels are present in myometrium. We determined the role of the cyclic ADP-ribose (cADPR)-signaling pathway in oxytocin-induced intracellular Ca2+ [(Ca2+)i] transients in human myometrial cells. We found that oxytocin-induced Ca2+ transient is dependent on several sources of Ca2+, including extracellular Ca2+ and intracellular Ca2+ stores. In addition, we found that both the 1,4,5-trisphosphate- and the cADPR-induced Ca2+ releasing systems are important for the induction of [Ca2+]i transients by oxytocin in human myometrial cells. Furthermore, we investigated TNFalpha regulation of oxytocin-induced [Ca2+]i transients, CD38 cyclase activity, and CD38 expression in human myometrial cells. We found that oxytocin-induced [Ca2+]i transients were significantly increased by 50 ng/ml TNF. Similarly, CD38 mRNA levels, CD38 expression, and cyclase activity were increased by TNFalpha, thus increasing cADPR levels. We propose that a complex interaction between multiple signaling pathways is important for the development of intracellular Ca2+ transients induced by oxytocin and that TNFalpha may contribute for the myometrium preparation for labor by regulating the cADPR-signaling pathway. The observation that the cADPR-signaling pathway is important for the development of intracellular Ca2+ transients in human myometrial cells raises the possibility that this signaling pathway could serve as a target for the development of new therapeutic strategies for abnormal myometrial contraction observed during pregnancy.

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Oxytocin-induced Ca2+ transients play an important role in myometrial contractions. Here, using a knockout model, we found that the enzyme CD38, responsible for the synthesis of the second messenger cyclic ADP-ribose (cADPR), plays an important role in the oxytocin-induced Ca2+ transients and contraction. We also observed that CD38 is necessary for TNF-α-increased agonist-stimulated Ca2+ transients in human myometrial cells. We provide experimental evidence that the TNF-α effect is mediated by increased expression of the enzyme CD38. First, we observed that TNF-α increased oxytocin-induced Ca2+ transients and CD38 expression in human myometrial cells. Moreover, using small interference RNA technology, we observed that TNF-α stimulation of agonist-induced Ca2+ transients was abolished by blocking the expression of CD38. In control experiments, we observed that activation of the component of the TNF-α signaling pathway, NF-κB, was not affected by the treatments. Finally, we observed that the effects of TNF-α on CD38 cyclase and oxytocin-induced Ca2+ transients are abolished by progesterone. In conclusion, we provide the first experimental evidence that CD38 is important for myometrial Ca2+ transients and contraction. Moreover, CD38 is necessary for the TNF-α-mediated augmentation of agonist-induced Ca2+ transients in myometrial cells. We propose that the balance between cytokines and placental steroids regulates the expression of CD38 in vivo and cell responsiveness to oxytocin.

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Active learning has the benefit of being more engaging and interactive, making it more suitable for adult learners who prefer a task/problem centered approach to learning. Implementation of small‐group sessions in the material‐rich course is not always possible and other alternatives that engage learners should be explored. To incorporate active learning strategies, a team learning exercise “Talking Points” (TP), was introduced in a microscopic anatomy sessions for first year medical students. At the beginning of the laboratory period, students were given 5–7 subject‐related basic science/clinical problems and were encouraged to discuss within small “ad hoc” formed teams. Near the end of the laboratory session, these items were discussed by the entire group. This exercise gave the students the opportunity to learn relevant clinical material within small teams and present their findings to other classmates. Many students remarked that TP facilitated their learning of the material, stimulated questions, encouraged peer teaching, and provided a preview of learning strategies for the final examination. The participation and students' performance during TP was not included in the final grade. Incorporation of the TP into the microscopic anatomy curriculum increased students' participation and ended the laboratory session with an enthusiastic conclusion.