Oxytocin receptors (Literature review) Part 2
Part 1 of the review reported on the structure of oxytocin receptors (OxR), the locations of OxR their expression, and the factors that regulate it. Part 2 reports positive modulators (estrogens, Mg2+ ions, cholesterol, testosterone, prostaglandins) and negative (progesterone, atrial natriuretic hormone) modulators of direct action, which respectively increase or decrease the effectiveness of OxR activation. The role of cholesterol as a kind of «switchman» that determines the kind of signaling pathway that is activated by oxytocin in a particular situation, and the affinity of the OxR to its agonists and antagonists (atosiban) are considered. The question of thein homogeneity of OxR is discussed. The process of desensitization of the OxR, which underlies the development of the weakness of labor activity, is considered in detail. In particular, such desensitization steps as phosphorylation of OxR (involving OxR kinase), beta-aresstin addition, internalization of the OxR, recycling of the OxR, inhibition of the expression of the mRNA of OxR under the influence of agonists of OxR or antagonists of OxR are considered. In general, the information contained in the work may stimulate the development of new methods aimed at using agonists and antagonists of the OxR to induction of labor, correction of weakness in labor, prevention of uterine bleeding and treatment of the threat of premature labor.