Glucose metabolism produces lactate and hydrogen ions in an anaerobic environment. Fetuses with intrauterine growth restriction are considered to become progressively lactacidemic as well as hypoxic. Roles of lactate in the placenta in the presence of fetal growth restriction (FGR) remain to be clarified. Immunohistochemical localization of lactate-related substances, such as a receptor for lactate (hydroxy-carboxylic acid 1 receptor (HCA1 receptor/GPR81)), monocarboxylate transporters (MCTs) for lactate, lactate dehydrogenases (LDHs), and proteins expressed in syncytiotrophoblasts or cytotrophoblasts was examined in placentas of appropriate weight for gestational age (AGA) fetus and those showing FGR. Immunoreactivity for the HCA1 receptor was present in the cytoplasm of some trophoblasts, predominantly localized to their basal (fetus-facing) side, and was frequently colocalized with that for E-cadherin or serine peptidase inhibitor, Kunitz type 1 (SPINT1), a marker protein of cytotrophoblasts. Immunoreactivity for MCT1 and MCT4 was present on the basal and the microvillous (maternal-facing) membranes of trophoblasts in both groups, respectively. Clear immunoreactivity for LDHA and LDHB was also observed in the cytoplasm of trophoblasts, mainly localized to their basal side. However, there were no significant differences in immunohistochemically stained areas of lactate-related substances between AGA and late-onset FGR groups. On the other hand, there were correlations between coefficients of the presence of chorioamnionitis and the values of LDHB and E-cadherin. Immunohistochemical localization of the HCA1 receptor was predominantly observed in the cytoplasm located on the basal side of trophoblasts, suggesting a role of lactate in human placental development, including syncytialization.

中文翻译：

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胎儿生长受限时胎盘中 HCA1 受体的免疫组织化学定位


葡萄糖代谢在无氧环境中产生乳酸和氢离子。宫内生长受限的胎儿被认为会逐渐出现乳酸血症和缺氧。在胎儿生长受限（FGR）的情况下，乳酸在胎盘中的作用仍有待阐明。乳酸相关物质的免疫组织化学定位，例如乳酸受体（羟基羧酸 1 受体（HCA1 受体/GPR81））、乳酸单羧酸转运蛋白 (MCT)、乳酸脱氢酶 (LDH) 以及合体滋养层或细胞滋养层中表达的蛋白质在体重适合胎龄 (AGA) 胎儿的胎盘和显示 FGR 的胎盘中进行了检查。 HCA1 受体的免疫反应性存在于一些滋养层细胞的细胞质中，主要位于其基底（面向胎儿）侧，并且经常与 E-钙粘蛋白或丝氨酸肽酶抑制剂 Kunitz 1 型 (SPINT1)（一种标记物）共定位细胞滋养细胞的蛋白质。两组滋养细胞的基底膜和微绒毛（面向母体）膜上分别存在 MCT1 和 MCT4 的免疫反应性。在滋养层细胞质中也观察到 LDHA 和 LDHB 的明显免疫反应性，主要位于其基底侧。然而，AGA 组和晚发型 FGR 组之间乳酸相关物质的免疫组化染色面积没有显着差异。另一方面，绒毛膜羊膜炎的存在系数与LDHB和E-钙粘蛋白的值之间存在相关性。 HCA1 受体的免疫组织化学定位主要在位于滋养层基底侧的细胞质中观察到，表明乳酸在人胎盘发育（包括合胞化）中的作用。