Vitamin E ameliorates alterations to the articular cartilage of knee joints induced by monoiodoacetate and diabetes mellitus in rats.

ABSTRACT

We recently reported an animal model of osteoarthritis (OA) induced by a combination of the chondrocyte glycolysis inhibitor, monoiodoacetate (MIA) and the agent that induces diabetes mellitus, streptozotocin (STZ). Here we investigated the potential protective effect of the antioxidant and anti-inflammatory agent, vitamin E against MIA+STZ-induced OA. Therefore, rats were either injected once with MIA (2 mg/50 µL) + 65 mg/kg STZ before being sacrificed after 8 weeks (model group) or were treated immediately after MIA+STZ injections with vitamin E (600 mg/kg; thrice a week) before being sacrificed after 8 weeks (treatment group). Using scanning and transmission electron microscopy examinations, we observed in the model group a substantial damage to the articular cartilage of the knee joint as demonstrated by the destruction of the chondrocytes, territorial matrix, disrupted lacunae, collagen fibers, and profound chondrocyte ultrastructural alterations such as degenerated chondrocyte, irregular cytoplasmic membrane, damaged mitochondria and rough endoplasmic reticulum, vacuolated cytoplasm, presence of lipid droplets and different sizes of lysosomes, which were substantially but not completely protected by vitamin E. H&E stained sections of knee joint articular cartilage showed that MIA+STZ induced damage to the chondrocyte and territorial matrix. Vitamin E also significantly (p < .05) inhibited MIA+STZ-induced blood levels of the inflammatory biomarkers, tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) that are known to be modulated in OA and diabetes. We conclude that vitamin E protects against MIA+STZ-induced knee joints injuries in rats, which is associated with the inhibition of biomarkers of inflammation.