Effects of 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) on vertebral bone mineralization and on thyroxin and vitamin D levels in Sprague–Dawley rats

• Published in: Toxicology letters Vol. 187; no. 2; pp. 63 - 68
• Main Authors: Alvarez-Lloret, Pedro, Lind, P. Monica, Nyberg, Ingrid, Örberg, Jan, Rodríguez-Navarro, Alejandro B.
• Format: Journal Article
• Language: English
• Published: Shannon Elsevier Ireland Ltd 01.06.2009; Elsevier
• Subjects: Animals; Biologi; Biological and medical sciences; Biology; Body Weight - drug effects; Bone and Bones - chemistry; Bone and Bones - drug effects; Bone and Bones - metabolism; Bone Density - drug effects; Bone mineral density; Durapatite - metabolism; Environmental Pollutants - toxicity; Female; FTIR; Lumbar Vertebrae - chemistry; Lumbar Vertebrae - drug effects; Lumbar Vertebrae - metabolism; Medical sciences; Medicin och hälsovetenskap; Microscopy, Electron, Transmission; NATURAL SCIENCES; NATURVETENSKAP; PCB126; Polychlorinated Biphenyls - toxicity; Rats; Rats, Sprague-Dawley; Spectroscopy, Fourier Transform Infrared; TEM; Thyroxin; Thyroxine - blood; Toxicology; Vitamin D; Vitamin D - analogs & derivatives; Vitamin D - blood; Bone mineral density; PCB126; Vitamin D; Thyroxin; TEM; FTIR; Rat; Rodentia; Osteoarticular system; Vertebrata; Mammalia; Transmission electron microscopy; Mineralization; Animal; Bone
• ISSN: 0378-4274; 1879-3169; 1879-3169
• DOI: 10.1016/j.toxlet.2009.01.030

The aim of the present study is to use Fourier transform infrared spectrometry (FTIR), and transmission electron microscopy (TEM) techniques, to make a more detailed description of toxic effects of 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) on bone tissue at the microstructural and at the molecular level as a result of an altered bone metabolism. We have analysed potential changes on vitamin D and thyroxin serum levels since these hormones represent endocrine endpoints that are critical for bone growth and development. For this purpose Sprague–Dawley rats were exposed ( n = 10) to PCB126 (i.p.) for 3 months (total dose, 384 μg/kg bodyweight), while control rats ( n = 10) were injected with corn oil (vehicle). Results from FTIR showed that vertebrae from the exposed rats had an overall lower degree of mineralization (−8.5%; p < 0.05) compared with the controls. In addition, results from peripheral quantitative computed tomography (pQCT) analyses showed significant increases in the trabecular bone mineral density (+12%; p < 0.05) in the exposed group compared with the controls. The TEM analyses also showed an alteration in the crystallinity properties of vertebral bone mineral with a significant decrease in the size and crystallinity of apatite crystal forming the bone tissue in the exposed vs. non-exposed rats. Serum analysis revealed lower levels of thyroid hormones, FT4 (−42%; p < 0.005), TT4 (−26%; p < 0.005), and vitamin D (−21%; p < 0.005) in exposed group compared to control animals. The complementary techniques (TEM and FTIR) used in this study have revealed insights into possible bone mineralization alteration due to PCB126 exposure. The lowering of both the thyroxin and vitamin D serum levels might be an underlying explanation for the observed effects on bone mineralization.