Our previous studies confirmed that prenatal caffeine exposure (PCE) could induce susceptibility to osteoarthritis in adult offspring rats due to poor chondrocyte differentiation, but its mechanism remains to be further investigated. This study aimed to explore whether subchondral bone dysplasia mediates susceptibility to osteoarthritis in adult offspring rats induced by PCE. Pregnant Wistar rats were treated with caffeine (120 mg/kg.d) or saline from gestational days (GD) 9 to 20. The female offspring were euthanized to collect femurs at GD20, postnatal week (PW) 6, and PW28 (non-ovariectomy and ovariectomy groups) to detect osteoarthritis-like phenotype, subchondral bone mass, ossification center development, and other evidence. The results showed that PCE increased the Mankin score of pathological articular cartilage, but decreased articular cartilage thickness and subchondral bone mass, which were more obvious after ovariectomy. Meanwhile, the correlation analysis results demonstrated that the Mankin score of articular cartilage was significantly negatively correlated with subchondral bone mass, and the thickness of articular cartilage was significantly positively correlated with subchondral bone mass. Further, the length and area of the primary and secondary ossification centers, the number of osteoblasts, and the related genes' expression of osteogenic differentiation (e.g., RUNX2, BSP, ALP, and OCN) were all significantly decreased in the PCE group before and after birth. Taken together, PCE induced susceptibility to osteoarthritis in adult female offspring, which was likely related to the subchondral bone dysplasia and reduction of subchondral bone mass production due to developmental disorder of primary and secondary ossification centers caused by osteoblast differentiation disability before and after birth.

中文翻译：

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软骨下骨发育不良介导产前咖啡因暴露诱导的雌性成年后代大鼠对骨关节炎的易感性

我们之前的研究证实，产前咖啡因暴露（PCE）可诱导成年后代大鼠由于软骨细胞分化不良而对骨关节炎的易感性，但其机制仍有待进一步研究。本研究旨在探讨软骨下骨发育不良是否介导 PCE 诱导的成年后代大鼠对骨关节炎的易感性。从妊娠天数 (GD) 9 到 20 用咖啡因 (120 mg/kg.d) 或生理盐水处理怀孕的 Wistar 大鼠。雌性后代在 GD20、产后周 (PW) 6 和 PW28（非卵巢切除术和卵巢切除术组）以检测骨关节炎样表型、软骨下骨量、骨化中心发育和其他证据。结果表明，PCE提高了病理性关节软骨的Mankin评分，但关节软骨厚度和软骨下骨量减少，在卵巢切除后更为明显。同时，相关性分析结果表明，关节软骨Mankin评分与软骨下骨量呈显着负相关，关节软骨厚度与软骨下骨量呈显着正相关。此外，PCE组的初级和次级骨化中心的长度和面积、成骨细胞数量以及成骨分化相关基因（如RUNX2、BSP、ALP和OCN）的表达均显着降低。出生后。总之，PCE 诱导成年雌性后代对骨关节炎的易感性，