Goldsmith L T, Weiss G, Steinetz B G
Department of Obstetrics and Gynecology, New Jersey Medical School, Newark, USA.
Endocrinol Metab Clin North Am. 1995 Mar;24(1):171-86.
Relaxin is a 6000-d polypeptide, structurally related to insulin and the insulin-like growth factors. Unlike insulin, the structure of which is remarkably well conserved among the vertebrates, relaxin sequences can vary by more than 50% between different species. Despite these large sequence variations, relaxins (with few exceptions) have very similar biologic activities in animal test systems. The reason for this has recently come to light: the receptor binding region of the B chain, in contrast to the rest of the molecule, is highly conserved between species. Relaxin is measured by bioassays employing interpubic ligament formation in mice and guinea pigs, and by inhibition of uterine motility. A more sensitive and efficient bioassay is urgently needed. In women, the target organs for relaxin are the uterine cervix, myometrium, endometrium, and decidua. Other presumptive but unproven targets are the pubic symphysis and sacroiliac joints, mammary glands, and pituitary gland. Circulating relaxin is secreted by the corpus luteum. The placenta, decidua, or both also produce relaxin, which does not enter the circulation but may act in an autocrine or paracrine fashion. hCG is a stimulus to luteal relaxin secretion. Other regulatory factors are poorly defined. Aluteal women are hyporelaxinemic, and yet are capable of normal vaginal delivery of their infants. Local effects of placental or decidual relaxin cannot be discounted in such subjects. Hyperrelaxinemia may occur in women with multiple gestations and ovarian stimulation, and may be associated with increased premature births. Serum relaxin also is elevated in pregnant diabetics, but its role in this condition has not been defined. Clearly, further investigations are needed to delineate the precise role of relaxin in human pregnancy.
松弛素是一种6000道尔顿的多肽，在结构上与胰岛素和胰岛素样生长因子相关。与胰岛素不同，胰岛素的结构在脊椎动物中高度保守，而松弛素序列在不同物种之间的差异可超过50%。尽管存在这些巨大的序列差异，但在动物试验系统中，松弛素（少数例外情况除外）具有非常相似的生物学活性。其原因最近已被揭示：与分子的其余部分相比，B链的受体结合区域在物种之间高度保守。松弛素通过利用小鼠和豚鼠耻骨间韧带形成的生物测定法以及通过抑制子宫运动来测量。迫切需要一种更灵敏和有效的生物测定法。在女性中，松弛素的靶器官是子宫颈、子宫肌层、子宫内膜和蜕膜。其他推测但未经证实的靶器官是耻骨联合和骶髂关节、乳腺和垂体。循环中的松弛素由黄体分泌。胎盘、蜕膜或两者也产生松弛素，其不进入循环，但可能以自分泌或旁分泌方式起作用。人绒毛膜促性腺激素是黄体松弛素分泌的刺激物。其他调节因子尚不明确。无黄体的女性松弛素水平较低，但仍能够正常阴道分娩婴儿。在此类受试者中，不能忽视胎盘或蜕膜松弛素的局部作用。多胎妊娠和卵巢刺激的女性可能会出现高松弛素血症，并且可能与早产增加有关。妊娠糖尿病患者的血清松弛素也会升高，但其在这种情况下的作用尚未明确。显然，需要进一步研究来阐明松弛素在人类妊娠中的精确作用。
