Plants hormones are widely used in agriculture to alter plant characteristics as growth regulators. Gibberellic acid (GA3) plays important role in promoting plant growth, and cell differentiation. This work was performed to investigate the relationship between lipooxidative damage marker (HEL) and bone damage induced by GA3 in adult albino rats. This study was carried out on 20 adult albino rats for 4 weeks treated 6 days/week. The rats were distributed into 2 groups of 10 rats each: Groups I (control) and II (GA3); each rat was treated by GA3 oral gavage (75 ppm) once daily. There was an increase in body and femur weights and length as compared to controls. GA3 caused a decrease in calcium and phosphorus levels in bone while calcium increased and the phosphorus decreased in the plasma. Lipid peroxidation markers caused high femur malondialdehyde levels with decrease in superoxide dismutase, catalase and glutathione peroxidase activities confirmed by histological changes. Immunohistochemical examination for expression of Nε-HEL in bone tissues showed strong positive brown reaction in GA3 treated group when compared with control group that showed negative reaction. GA3 toxicity induced bone damage in adult albino rats. It is recommended to increase public awareness regarding the health impact of gibberellic acid.

Keywords: Bone, gibberellic acid, lipid per oxidation, Nε-hexanoyl Lysine