title: Effects of Low-Dose versus High-Dose γ-Tocotrienol on the Bone Cells Exposed to the Hydrogen Peroxide-Induced Oxidative Stress and Apoptosis.
abstract: Oxidative stress and apoptosis can disrupt the bone formation activity of osteoblasts which can lead to osteoporosis. This study was conducted to investigate the effects of γ-tocotrienol on lipid peroxidation, antioxidant enzymes activities, and apoptosis of osteoblast exposed to hydrogen peroxide (H(2)O(2)). Osteoblasts were treated with 1, 10, and 100 μM of γ-tocotrienol for 24 hours before being exposed to 490 μM (IC(50)) H(2)O(2) for 2 hours. Results showed that γ-tocotrienol prevented the malondialdehyde (MDA) elevation induced by H(2)O(2) in a dose-dependent manner. As for the antioxidant enzymes assays, all doses of γ-tocotrienol were able to prevent the reduction in SOD and CAT activities, but only the dose of 1 μM of GTT was able to prevent the reduction in GPx. As for the apoptosis assays, γ-tocotrienol was able to reduce apoptosis at the dose of 1 and 10 μM. However, the dose of 100 μM of γ-tocotrienol induced an even higher apoptosis than H(2)O(2). In conclusion, low doses of γ-tocotrienol offered protection for osteoblasts against H(2)O(2) toxicity, but itself caused toxicity at the high doses.
authors.affiliation: Department of Pharmacology, Faculty of Medicine, National University of Malaysia (UKM), Kuala Lumpur Campus, Raja Muda Abdul Aziz Road, 50300 Kuala Lumpur, Malaysia.
authors.forename: Nizar
authors.initials: N
authors.lastname: Abd Manan
authors.forename: Norazlina
authors.initials: N
authors.lastname: Mohamed
authors.forename: Ahmad Nazrun
authors.initials: AN
authors.lastname: Shuid