Cigarette smoking is the largest cause of preventable deaths, and a known risk factor for musculoskeletal issues including rotator cuff tendon tears. Tendon degeneration is believed to be due in part to changes in tendon cell health and collagen structure. Several studies have demonstrated that exposure to nicotine negatively impacts tendon healing, but surprisingly, nicotine exposure was shown to increase rat supraspinatus tendon stiffness. In order to address this seeming contradiction, the objective of this study was to comprehensively investigate the effects of long-term (18 weeks) exposure of nicotine on tendon-to-bone microstructural properties in a rat model. We hypothesized that long term subcutaneous nicotine delivery would lead to diminished tendon mechanical properties, decreased bone microstructure in the humeral head, and altered tendon cell morphology compared to age-matched control rats receiving saline. Results demonstrated a small decrease in tendon size and stiffness, with decreased cell density in the tendon midsubstance. However, no differences were found in the enthesis fibrocartilage or in the underlying subchondral or trabecular bone. In conclusion, our study revealed limited effects of nicotine on the homeostatic condition of the supraspinatus tendon, enthesis, and underlying bone. Future studies are needed to ascertain effects of other components of tobacco products.

吸烟是可预防死亡的最大原因，也是肌肉骨骼问题的已知风险因素，包括肩袖肌腱撕裂。肌腱退化被认为部分是由于肌腱细胞健康和胶原蛋白结构的变化。几项研究表明，暴露于尼古丁会对肌腱愈合产生负面影响，但令人惊讶的是，尼古丁暴露会增加大鼠冈上肌腱的硬度。为了解决这一看似矛盾的问题，本研究的目的是全面研究长期（18 周）暴露于尼古丁对大鼠模型中肌腱-骨显微结构特性的影响。我们假设长期皮下注射尼古丁会导致肌腱力学性能下降，肱骨头骨微结构减少，与接受盐水的年龄匹配的对照大鼠相比，肌腱细胞形态发生了改变。结果表明肌腱大小和刚度略有下降，肌腱中间物质中的细胞密度降低。然而，在附着点纤维软骨或下面的软骨下骨或小梁骨中没有发现差异。总之，我们的研究揭示了尼古丁对冈上肌腱、附着点和底层骨骼的稳态影响有限。需要进一步的研究来确定烟草制品其他成分的影响。在附着点纤维软骨或下面的软骨下骨或小梁骨中没有发现差异。总之，我们的研究揭示了尼古丁对冈上肌腱、附着点和底层骨骼的稳态影响有限。需要进一步的研究来确定烟草制品其他成分的影响。在附着点纤维软骨或下面的软骨下骨或小梁骨中没有发现差异。总之，我们的研究揭示了尼古丁对冈上肌腱、附着点和底层骨骼的稳态影响有限。需要进一步的研究来确定烟草制品其他成分的影响。