Cadmium (Cd) is toxic to the skeletal system resulting in bone loss and pain. We aimed at determining the effect of chronic Cd exposure on bone density and microarchitecture along with changes in the density of a subset of sensory and sympathetic nerve fibers innervating the developing rat femur. Newborn male Wistar rats were injected daily for 49 days with CdCl₂ (1 mg/kg i.p.) or saline solution (control group). At the day of sacrifice, levels of Cd in the right femur, liver and kidney were determined by atomic absorption spectrophotometry. Additionally, microCT followed by immunohistochemical analyses were performed in the left femur. Results showed Cd accumulation in trabecular bone neared levels seen in liver and kidney. Cd concentration in cortical bone was significantly lower versus trabecular bone. MicroCT analysis revealed that Cd-exposed rats had a significant decrease in trabecular bone parameters at the distal femoral metaphysis; however, most of the cortical bone parameters were not significantly affected. Cd-exposed rats showed a significant loss of TH⁺ sympathetic nerve fibers, but not of CGRP⁺ sensory nerve fibers, at the level of bone marrow of the femoral diaphysis as compared to control rats. This study shows that Cd negatively affects bone density and microarchitecture of trabecular bone and decreases the density of sympathetic nerve fibers innervating rat femur. Future studies are warranted to determine the toxigenic mechanisms of Cd on sympathetic nerves and how sympathetic denervation influences bone loss in animals exposed to Cd.

镉 (Cd) 对骨骼系统有毒，导致骨质流失和疼痛。我们旨在确定慢性 Cd 暴露对骨密度和微结构的影响，以及支配发育中的大鼠股骨的感觉和交感神经纤维子集的密度变化。新生雄性 Wistar 大鼠每天注射 CdCl _{2 ，}持续 49 天(1 mg/kg ip) 或生理盐水 (对照组)。在处死当天，通过原子吸收分光光度法测定右侧股骨、肝脏和肾脏中的 Cd 水平。此外，在左侧股骨中进行了 microCT，然后进行了免疫组织化学分析。结果显示小梁骨中的 Cd 积累接近肝脏和肾脏中的水平。皮质骨中的镉浓度显着低于骨小梁。MicroCT 分析显示，Cd 暴露大鼠股骨远端干骺端骨小梁参数显着降低；然而，大部分皮质骨参数并未受到显着影响。暴露于镉的大鼠表现出显着的 TH ⁺交感神经纤维丢失，但没有显着丢失CGRP ⁺与对照大鼠相比，感觉神经纤维在股骨骨干的骨髓水平。该研究表明，Cd 对骨密度和骨小梁的微结构产生负面影响，并降低支配大鼠股骨的交感神经纤维的密度。未来的研究需要确定 Cd 对交感神经的产毒机制，以及去交感神经支配如何影响暴露于 Cd 的动物的骨质流失。